[Federal Register Volume 73, Number 96 (Friday, May 16, 2008)]
[Rules and Regulations]
[Pages 28321-28350]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-10768]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 51 and 52
[EPA-HQ-OAR-2003-0062; FRL-8566-1]
RIN 2060-AN86
Implementation of the New Source Review (NSR) Program for
Particulate Matter Less Than 2.5 Micrometers (PM2.5)
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The EPA is finalizing regulations to implement the New Source
Review (NSR) program for fine particulate matter (that is, particles
with an aerodynamic diameter less than or equal to a nominal 2.5
micrometers,
[[Page 28322]]
generally referred to as ``PM2.5''). The NSR program was
created by the Clean Air Act (Act or CAA) to ensure that stationary
sources of air pollution are constructed or modified in a manner that
is consistent with air quality goals in the area.
The Clean Air Fine Particle Implementation Rule, which was proposed
in the Federal Register on November 1, 2005, included requirements and
guidance for State and local air pollution agencies to follow in
developing State implementation plans (SIPs) and also the NSR
provisions. The final implementation rule that was promulgated on April
25, 2007, included all the SIPs related provisions. In this rulemaking,
EPA is finalizing the NSR provisions of the November 1, 2005 proposed
rule including the major source threshold, significant emissions rate,
and offset ratios for PM2.5, interpollutant trading for
offsets and applicability of NSR to PM2.5 precursors.
DATES: This final rule is effective on July 15, 2008.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2003-0062. All documents in the docket are
listed on the www.regulations.gov Web site. Although listed in the
index, some information may not be publicly available, e.g., CBI or
other information whose disclosure is restricted by statute. Certain
other material, such as copyrighted material, is not placed on the
Internet and will be publicly available only in hard copy form.
Publicly available docket materials are available either electronically
through www.regulations.gov or in hard copy at the Air Docket, EPA/DC,
EPA West, Room 3334, 1301 Constitution Avenue, Northwest, Washington,
DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday
through Friday, excluding legal holidays. The telephone number for the
Public Reading Room is (202) 566-1744, and the telephone number for the
Air Docket is (202) 566-1742.
FOR FURTHER INFORMATION CONTACT: Mr. Raghavendra (Raj) Rao, Air Quality
Policy Division, Office of Air Quality Planning and Standards (C504-
03), U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina 27711, telephone number: (919) 541-5344, facsimile
number: (919) 541-5509, e-mail address: [email protected]; or Mr. Dan
deRoeck, at the same address, telephone 919-541-5593, or e-mail at
[email protected].
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this action apply to me?
Entities affected by this rule include sources in all industry
groups. The majority of sources potentially affected are expected to be
in the following groups:
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Industry group NAICS \a\
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Electric services...................... 221111, 221112, 221113, 221119,
221121, 221122
Petroleum refining..................... 32411
Industrial inorganic chemicals......... 325181, 32512, 325131, 325182,
211112, 325998, 331311, 325188
Industrial organic chemicals........... 32511, 325132, 325192, 325188,
325193, 32512, 325199
Miscellaneous chemical products........ 32552, 32592, 32591, 325182,
32551
Natural gas liquids.................... 211112
Natural gas transport.................. 48621, 22121
Pulp and paper mills................... 32211, 322121, 322122, 32213
Paper mills............................ 322121, 322122
Automobile manufacturing............... 336111, 336112, 336712, 336211,
336992, 336322, 336312, 33633,
33634, 33635, 336399, 336212,
336213
Pharmaceuticals........................ 325411, 325412, 325413, 325414
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\a\ North American Industry Classification System.
Entities affected by this rule also include States, local reviewing
authorities, and Indian country with new and modified major stationary
sources.
B. Where can I get a copy of this document and other related
information?
In addition to being available in the docket, an electronic copy of
this final rule will also be available on the World Wide Web. Following
signature by the EPA Administrator, a copy of this final rule will be
posted in the regulations and standards section of our NSR home page
located at http://www.epa.gov/nsr.
C. How is this preamble organized?
The information presented in this preamble is organized as follows:
I. General Information
A. Does this action apply to me?
B. Where can I get a copy of this document and other related
information?
C. How is this preamble organized?
II. Purpose
III. Background
A. New Source Review (NSR) Program
B. Fine Particulate Matter and the NAAQS for PM2.5
C. Implementation of NSR for PM2.5
IV. Overview of This Final Action
V. Rationale for Final Actions
A. Applicability of NSR to Precursors of PM2.5 in the
Ambient Air
1. What is EPA's legal authority to regulate precursors?
2. What is EPA's approach for addressing precursors?
3. Final Action on SO2
4. Final Action on NOX
5. Final Action on VOC
6. Final Action on Ammonia
B. Major Stationary Source Threshold for PM2.5
C. Significant Emissions Rate for Direct Emissions of
PM2.5
D. Significant Emissions Rates for PM2.5 Precursors
E. Condensable PM Emissions
F. Prevention of Significant Deterioration (PSD) Program
Requirements
1. How must BACT be implemented for PM2.5?
2. How does EPA plan to address PM2.5 Increments,
Significant Impact Levels (SILs), and Significant Monitoring
Concentrations (SMCs)?
3. What is the ambient air quality analysis requirement for
PM2.5?
4. How must the PSD preconstruction monitoring requirement be
implemented for PM2.5?
G. Nonattainment New Source Review (NA NSR) Requirements
1. What is the required offset ratio for direct PM2.5
emissions?
2. Which precursors are subject to the offset requirement?
3. What is the required offset ratio for PM2.5
precursors?
4. Is interpollutant trading allowable to comply with offset
requirements?
H. How will the transition to the PM2.5 PSD
requirements occur?
1. Background
2. Transition for ``Delegated States''
3. Transition for ``SIP-Approved States''
I. How will the transition to the PM2.5 NA NSR
requirements occur?
1. Background
2. Transition
[[Page 28323]]
3. Implementation of NSR Under the ``Emissions Offset
Interpretative Ruling'' (40 CFR part 51, appendix S) with Revisions
J. Does major NSR apply to PM2.5 precursors during
the SIP development period?
K. Are there any Tribal concerns?
L. What are the requirements for minor NSR for PM2.5?
M. Rural Transport Areas
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132--Federalism
F. Executive Order 13175--Consultation and Coordination with
Indian Tribal Governments
G. Executive Order 13045--Protection of Children from
Environmental Health and Safety Risks
H. Executive Order 13211--Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898--Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Congressional Review Act
L. Petitions for Judicial Review
M. Determination Under Section 307(d)
VII. Statutory Authority
II. Purpose
The purpose of this rulemaking is to finalize the major NSR program
provisions for PM2.5. This final rule supplements the final
implementation rule for PM2.5 (excluding the NSR provisions)
that we \1\ promulgated on April 25, 2007 at 72 FR 20586. This final
action on the bulk of the major NSR program for PM2.5 along
with our proposed rule on increments, SILs, and SMC, when final, will
represent the final elements necessary to implement a PM2.5
PSD program. When both rules are promulgated and in effect, the
PM2.5 PSD program will no longer use a PM10
program as a surrogate, as has been the practice under our existing
guidance.
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\1\ In this proposal, the terms ``we,'' ``us,'' and ``our,''
refer to the EPA and the terms ``you,'' and ``your,'' refer to the
owners or operators of stationary sources of air pollution.
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III. Background
A. New Source Review (NSR) Program
The existing regulations require both major and minor NSR programs
to address any pollutant for which there is a National Ambient Air
Quality Standard (NAAQS) and precursors to the formation of such
pollutant when identified for regulation by the Administrator. This
final rule amends the NSR regulations to establish the minimum elements
for State, local, and Tribal agency programs implementing NSR for the
PM2.5 NAAQS. This preamble also explains what interim
provisions would apply with respect to PM2.5 during the
State Implementation Plan (SIP) development period.
The NSR program is a preconstruction permitting program that
applies when a source is constructed or modified. The NSR program is
composed of three different programs:
Prevention of Significant Deterioration (PSD);
Nonattainment NSR (NA NSR); and
Minor NSR.
We often refer to the PSD and NA NSR programs together as the major NSR
program because these programs regulate only major sources.\2\
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\2\ The Act uses the terms ``major emitting facility'' to refer
to sources subject to the PSD program, and ``major stationary
source'' to refer to sources subject to NA NSR. See CAA sections
165, 169, 172(c)(5), and 302(j). For ease of reference, we use the
term ``major source'' to refer to both terms.
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The PSD program applies when a major source that is located in an
area that is designated as attainment or unclassifiable for any
criteria pollutant is constructed or undergoes a major
modification.3 4 The NA NSR program applies when a major
source that is located in an area that is designated as nonattainment
for any criteria pollutant is constructed or undergoes a major
modification. The minor NSR program addresses both major and minor
sources that undertake construction or modification activities that do
not qualify as major, and it applies regardless of the designation of
the area in which a source is located.
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\3\ The term ``criteria pollutant'' means a pollutant for which
we have set a NAAQS.
\4\ In addition, the PSD program applies to most noncriteria
regulated pollutants.
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The national regulations that apply to each of these programs are
located in the Code of Federal Regulations (CFR) as shown in the
following table:
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Program Applicable regulations
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PSD.................................... 40 CFR 52.21, 40 CFR 51.166, 40
CFR 51.165(b).
NA NSR................................. 40 CFR 52.24, 40 CFR 51.165, 40
CFR part 51, appendix S.
Minor NSR.............................. 40 CFR 51.160-164.
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The PSD requirements include but are not limited to:
Installation of Best Available Control Technology (BACT);
Air quality monitoring and modeling analyses to ensure
that a project's emissions will not cause or contribute to a violation
of any NAAQS or maximum allowable pollutant increase (PSD increment);
Notification of Federal Land Manager of nearby Class I
areas; and
Public comment on the permit.
Nonattainment NSR requirements include but are not limited to:
Installation of Lowest Achievable Emission Rate (LAER)
control technology;
Offsetting new emissions with creditable emissions
reductions;
Certification that all major sources owned and operated in
the State by the same owner are in compliance with all applicable
requirements under the Act;
An alternative siting analysis demonstrating that the
benefits of the proposed source significantly outweigh the
environmental and social costs imposed as a result of its location,
construction, or modification; and
Public comment on the permit.
Minor NSR programs must meet the statutory requirements in section
110(a)(2)(C) of the Act, which requires ``* * * regulation of the
modification and construction of any stationary source * * * as
necessary to assure that national ambient air quality standards are
achieved.''
B. Fine Particulate Matter and the NAAQS for PM2.5
Fine particles in the atmosphere are made up of a complex mixture
of components. Common constituents include sulfate (SO4);
nitrate (NO3); ammonium; elemental carbon; a great variety
of organic compounds; and inorganic material (including metals, dust,
sea salt, and other trace elements) generally referred to as
``crustal'' material, although it may contain material from other
sources. Airborne particulate matter (PM) with a nominal aerodynamic
diameter of 2.5 micrometers or less (a micrometer is
[[Page 28324]]
one-millionth of a meter, and 2.5 micrometers is less than one-seventh
the average width of a human hair) are considered to be ``fine
particles,'' and are also known as PM2.5. ``Primary''
particles are emitted directly into the air as a solid or liquid
particle (e.g., elemental carbon from diesel engines or fire
activities, or condensable organic particles from gasoline engines).
``Secondary'' particles (e.g., sulfate and nitrate) form in the
atmosphere as a result of various chemical reactions.
The health effects associated with exposure to PM2.5 are
significant. Epidemiological studies have shown a significant
correlation between elevated PM2.5 levels and premature
mortality. Other important effects associated with PM2.5
exposure include aggravation of respiratory and cardiovascular disease
(as indicated by increased hospital admissions, emergency room visits,
absences from school or work, and restricted activity days), lung
disease, decreased lung function, asthma attacks, and certain
cardiovascular problems. Individuals particularly sensitive to
PM2.5 exposure include older adults, people with heart and
lung disease, and children.
On July 18, 1997, we revised the NAAQS for PM to add new standards
for fine particles, using PM2.5 as the indicator. We
established health-based (primary) annual and 24-hour standards for
PM2.5 (62 FR 38652). We set an annual standard at a level of
15 micrograms per cubic meter ([mu]g/m\3\) and a 24-hour standard at a
level of 65 [mu]g/m\3\. At the time we established the primary
standards in 1997, we also established welfare-based (secondary)
standards identical to the primary standards. The secondary standards
are designed to protect against major environmental effects of
PM2.5 such as visibility impairment, soiling, and materials
damage.
On October 17, 2006, we revised the primary and secondary NAAQS for
PM2.5 and PM10. In that rulemaking, we reduced
the 24-hour NAAQS for PM2.5 to 35 [mu]g/m\3\ and retained
the existing annual PM2.5 NAAQS of 15 [mu]g/m\3\. In
addition, we retained PM10 as the indicator for coarse PM,
retained the existing PM10 24-hour NAAQS of 150 [mu]g/m\3\,
and revoked the annual PM10 NAAQS (which had previously been
set at 50 [mu]g/m\3\). See 71 FR 61236.
C. Implementation of NSR for PM2.5
After we promulgated the NAAQS for PM2.5 in 1997, we
issued a guidance document entitled ``Interim Implementation for the
New Source Review Requirements for PM2.5'' (John S. Seitz,
EPA, October 23, 1997).\5\ As noted in that guidance, section 165 of
the Act suggests that PSD requirements become effective for a new NAAQS
upon the effective date of the NAAQS. Section 165(a)(1) of the Act
provides that no new or modified major source may be constructed
without a PSD permit that meets all of the section 165(a) requirements
with respect to the regulated pollutant. Moreover, section 165(a)(3)
provides that the emissions from any such source may not cause or
contribute to a violation of any NAAQS. Also, section 165(a)(4)
requires BACT for each pollutant subject to PSD regulation. The 1997
guidance stated that sources would be allowed to use implementation of
a PM10 program as a surrogate for meeting PM2.5
NSR requirements until certain difficulties were resolved, primarily
the lack of necessary tools to calculate the emissions of
PM2.5 and related precursors, the lack of adequate modeling
techniques to project ambient impacts, and the lack of PM2.5
monitoring sites.
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\5\ Available in the docket for this rulemaking, ID No. EPA-HQ-
OAR-2003-0062, and at http://www.epa.gov/region07/programs/artd/air/nsr/nsrmemos/pm25.pdf.
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On April 5, 2005, we issued a guidance document entitled
``Implementation of New Source Review Requirements in PM-2.5
Nonattainment Areas'' (Stephen D. Page, EPA).\6\ This memorandum
provides guidance on the implementation of the nonattainment major NSR
provisions in PM2.5 nonattainment areas in the interim
period between the effective date of the PM2.5 NAAQS
designations (April 5, 2005) and the promulgation date of the final NSR
regulations reflected in this action. Besides affirming the
continuation of the Seitz guidance memo in PM2.5 attainment
areas, the April 5, 2005 memo recommends that until we promulgate the
PM2.5 major NSR regulations, States should use a
PM10 nonattainment major NSR program as a surrogate to
address the requirements of nonattainment major NSR for
PM2.5.
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\6\ Available in the docket for this rulemaking, ID. No. EPA-HQ-
OAR-2003-0062, and at http://www.epa.gov/nsr/documents/nsrmemo.pdf.
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On November 1, 2005, we proposed a rule to implement the 1997
PM2.5 NAAQS, including proposed revisions to the NSR program
(70 FR 65984). As discussed above, this action finalizes the portion of
that proposal related to NSR. The other portions of that proposal,
concerning attainment dates, SIP submittals, reasonable further
progress (RFP) requirements, etc., were finalized on April 25, 2007 (72
FR 20586).
On September 21, 2007, we proposed additional elements for the PSD
program for PM2.5 including PM2.5 ``increments,''
significant impact levels (SILs), and significant monitoring
concentrations (SMCs) (72 FR 54112). Increments are the maximum
allowable increases over baseline concentrations that can be permitted
to occur when a major source is constructed or modified. This is one
mechanism by which the PSD program prevents significant deterioration
in air quality. A SIL defines the level of ambient air impact that is
considered a ``significant contribution'' to air quality. If the
modeled maximum ambient impacts of a new source or modification are
below the SILs, the source: (1) Is presumed not to cause or contribute
significantly to a PSD increment or NAAQS violation, and (2) is not
required to perform the multiple-source, cumulative impacts assessments
that are otherwise required under PSD. An SMC defines the level of
modeled ambient air impact below which the reviewing authority may
exempt a new or modified source from conducting the preconstruction
monitoring that may otherwise be required under PSD. The reviewing
authority may also exempt the source from preconstruction monitoring if
the existing monitored ambient concentration is less than the SMC. This
final action on the bulk of the major NSR program for PM2.5
along with our proposed rule on increments, SILs, and SMC, when final,
will represent the final elements necessary to implement a
PM2.5 PSD program. When both rules are promulgated and in
effect, the PM2.5 PSD program will no longer use a
PM10 program as a surrogate, as has been the practice under
our existing guidance.
IV. Overview of This Final Action
The table below summarizes the main elements of the existing NSR
program that this action addresses for PM2.5 as a regulated
NSR pollutant. The table indicates our final position on an issue and
whether our position has changed based on comments received. Our final
action for each element, or where appropriate, explanation of
implementation under existing
[[Page 28325]]
regulations, is addressed in detail in the referenced sections of this
preamble.
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NSR program element Final action Section
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Applicability to PM2.5 precursors.... SO2--Must be regulated as precursor, NOX-- V.A
Presumed regulated, VOC--Presumed not
regulated, Ammonia--Presumed not regulated.
PSD major source threshold........... 100/250 tons per year (tpy)..................... V.B
NA NSR major source threshold........ 100 tpy......................................... V.B
Significant emissions rate........... Direct PM2.5 emissions--10 tpy, SO2 precursor-- V.C & V.D
40 tpy, NOX precursor--40 tpy, if regulated.
Condensable PM2.5 emissions.......... Included in direct PM2.5 emissions for major NSR V.E
applicability determinations after the end of
the transition period (changed based on
comments received).
Control technology: BACT and LAER.... Applies for direct PM2.5 emissions, SO2, and V.F.1 & V.G
other precursors if regulated.
Prevention of significant Increments, SILs and SMCs covered in a separate V.F.2
deterioration. rulemaking.
Air quality impact analysis.......... Applies for PM2.5............................... V.F.3
Preconstruction monitoring........... Applies for PM2.5 (finalizing options 1 & 3).... V.F.4
NA NSR Statewide compliance and Applies for direct PM2.5 emissions and V.G
alternative siting analyses. precursors, if regulated.
NA NSR offsets....................... Applies for direct PM2.5 emissions and V.G.1-3
precursors, if regulated.
Interpollutant offsetting............ Allowed on a regional or statewide basis; EPA is V.G.4
issuing guidance with recommended regional
hierarchies and trading ratios (changed based
on comments received).
Transition for PSD................... Continues to use PM10 as a surrogate............ V.H
Transition for NA NSR................ Applies through an approved SIP or through 40 V.I
CFR part 51, appendix S.
SIP development period............... Clarifies that major NSR does not apply to V.J
precursors during the SIP development period in
attainment areas (changed based on comments
received).
Tribal concerns...................... Cross references to proposed NSR rules for V.K
Indian country.
Minor NSR............................ Clarifies that State and local regulatory V.L
programs must include PM2.5 requirements for
minor sources.
NSR transport option................. Transport classification not available.......... V.M
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The provisions of the PM2.5 major NSR program finalized
in this action are codified as revisions in the previously existing
regulatory text. The revisions to NA NSR are codified in 40 CFR 51.165
and appendix S to 40 CFR part 51. The PSD revisions are codified in 40
CFR 51.166 and 52.21.
V. Rationale for Final Actions
In this section we discuss each element of our proposal for this
rulemaking, explain our final action, discuss the rationale for our
final action, and summarize the major public comments we received. The
full summary of public comments on the proposal, along with our
responses, can be found in the docket for this rulemaking.\7\
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\7\ See ``Implementation of the New Source Review (NSR) Program
for Particulate Matter Less Than 2.5 Micrometers in Diameter
(PM2.5); Response to Comments,'' U.S. Environmental
Protection Agency. It can be viewed or downloaded at
www.regulations.gov, Docket ID No. EPA-HQ-OAR-2003-0062.
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A. Applicability of NSR to Precursors of PM2.5 in the
Ambient Air
Scientific research has shown that various pollutants can
contribute to ambient PM2.5 concentrations. In addition to
direct PM2.5 emissions, these include the following
precursors:
Sulfur dioxide (SO2);
Oxides of nitrogen (NOX);
Volatile organic compounds (VOC); and
Ammonia.
These gas-phase precursors undergo chemical reactions in the
atmosphere to form secondary PM. Formation of secondary PM depends on
numerous factors including the concentrations of precursors; the
concentrations of other gaseous reactive species; atmospheric
conditions including solar radiation, temperature, and relative
humidity; and the interactions of precursors with preexisting particles
and with cloud or fog droplets. Several atmospheric aerosol species,
such as ammonium nitrate and certain organic compounds, are semi-
volatile and are found in both gas and particle phases. Given the
complexity of PM formation processes, new information from the
scientific community continues to emerge to improve our understanding
of the relationship between sources of PM precursors and secondary
particle formation.
Precursors contribute significantly to ambient PM2.5
concentrations, producing approximately half of the concentration
nationally. In most areas of the country, PM2.5 precursor
emissions are major contributors to ambient PM2.5
concentrations. The relative contribution to ambient PM2.5
concentrations from each of these pollutants varies by area. The
relative effect of reducing emissions of these pollutants is also
highly variable.
Some PM2.5 precursors are already subject to major NSR
under other NAAQS, as shown in the following table:
------------------------------------------------------------------------
Existing program coverage for
PM2.5 precursor major NSR applicability
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NOX.................................... NA NSR and PSD for NO2 and
Ozone.
SO2.................................... NA NSR and PSD for SO2.
VOC.................................... NA NSR and PSD for Ozone.
Ammonia................................ No coverage for NSR.
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In the subsections that follow, we first discuss our legal
authority under the Act for regulating precursors to the formation of
criteria pollutants, and then discuss our final action for each of the
PM2.5 precursors.
1. What is EPA's legal authority to regulate precursors?
As we discussed in the November 1, 2005 proposal, we interpret the
Act to not only provide explicit authority for EPA to regulate
precursors, but also to grant us discretion to determine how to address
precursors for particular regulatory purposes. This reading is based on
section 302(g) of the Act, which defines the term ``air pollutant'' to
include ``any precursors to the formation of any air pollutant, to the
extent the Administrator has identified such precursor or precursors
for the particular purpose for which the term `air pollutant' is
used.'' The first clause of this second sentence in section 302(g)
explicitly authorizes the Administrator
[[Page 28326]]
to identify and regulate precursors as air pollutants under other parts
of the Act. In addition, the second clause of the sentence indicates
that the Administrator has discretion to identify which pollutants
should be classified as precursors for particular regulatory purposes.
Thus, we do not necessarily construe the Act to require that EPA
identify a particular precursor as an air pollutant for all regulatory
purposes where it can be demonstrated that various programs under the
Act address different aspects of the air pollutant problem. Likewise,
we do not interpret the Act to require that EPA treat all precursors of
a particular pollutant the same under any one program when there is a
basis to distinguish between such precursors within that program. For
example, in a recent rule addressing PM2.5 precursors for
purposes of the transportation conformity program, we chose to adopt a
different approach for one precursor based on the limited emissions of
that precursor from onroad mobile sources and the degree to which it
contributes to PM2.5 concentrations (70 FR 24280, May 6,
2005).
Other provisions of the Act reinforce our reading of section 302(g)
to mean that Congress intended precursors to NAAQS pollutants to be
subject to the air quality planning and control requirements of the
Act, but also recognized that there may be circumstances where it is
not appropriate to subject precursors to certain requirements of the
Act. Section 182 of the Act provides for the regulation of
NOX and VOC as precursors to ozone in ozone nonattainment
areas, but also provides in section 182(f) that major stationary
sources of NOX (an ozone precursor) are not subject to
emission reduction requirements for ozone where the State shows through
modeling that NOX reductions do not decrease ozone. Section
189(e) provides for the regulation of PM10 precursors in
PM10 nonattainment areas, but also recognizes that there may
be certain circumstances (e.g., if precursor emission sources do not
significantly contribute to PM10 levels) where it is not
appropriate to apply control requirements to PM10
precursors. The legislative history of section 189(e) recognized the
complexity behind the science of precursor transformation into
PM10 ambient concentrations and the need to harmonize the
regulation of PM10 precursors with other provisions of the
Act:
The Committee notes that some of these precursors may well be
controlled under other provisions of the CAA. The Committee intends
that * * * the Administrator will develop models, mechanisms, and
other methodology to assess the significance of the PM10
precursors in improving air quality and reducing PM10.
Additionally, the Administrator should consider the impact on ozone
levels of PM10 precursor controls. The Committee expects
the Administrator to harmonize the PM10 reduction
objective of this section with other applicable regulations of this
CAA regarding PM10 precursors, such as NOX.
See H. Rpt. 101-490, Pt. 1, at 268 (May 17, 1990), reprinted in S. Prt.
103-38, Vol. II, at 3292.
In summary, section 302(g) of the Act clearly calls for the
regulation of precursor pollutants, but the Act also identifies
circumstances when it may not be appropriate to regulate precursors and
gives the Administrator discretion to determine how to address
particular precursors under various programs required by the Act. Due
to the complexities associated with precursor emissions and their
variability from location to location, we believe that in certain
situations it may not be effective or appropriate to control a certain
precursor under a particular regulatory program or for EPA to require
similar control of a particular precursor in all areas of the country.
The term ``air pollutant,'' as defined in section 302(g), is
incorporated into the NSR provisions for various purposes. Thus, we
interpret section 302(g) of the Act to require us to consider how to
address precursors under the NSR program.
With regard to PSD, section 165(a)(3) of the Act states that new or
modified major sources must demonstrate that emissions ``will not
cause, or contribute to, air pollution in excess of any * * * NAAQS in
any air quality control region * * *.'' A source could not reasonably
make this demonstration without considering precursors that EPA has
identified for this purpose. Section 165(a)(4) of the Act states that a
new or modified source must apply BACT ``for each pollutant subject to
regulation under this Act emitted from, or which results from, such
facility.'' The phrase ``emitted from, or which results from''
indicates that the statute is not limited to direct emissions, but
rather extends to precursors as well.
With regard to NA NSR, sections 172(c)(4) and 173 require States to
demonstrate, among other things, that emissions from new or modified
major sources are consistent with the achievement of ``reasonable
further progress.'' Reasonable further progress is further defined as
reductions of the relevant air pollutant, which is defined in section
302(g) to include precursors identified by EPA as subject to regulation
for that purpose.
2. What is EPA's approach for addressing precursors?
As proposed, we are finalizing different approaches for addressing
the individual precursors to PM2.5 under the Act's NSR
provisions. Generally, where the scientific data and modeling analyses
provide reasonable certainty that the pollutant's emissions are a
significant contributor to ambient PM2.5 concentrations, we
believe that pollutant should be identified as a ``regulated NSR
pollutant'' and subject to the PM2.5 NSR provisions.
Conversely, where the effect of a pollutant's emissions on ambient
PM2.5 concentrations is subject to substantial uncertainty,
such that in some circumstances the pollutant may not result in
formation of PM2.5, or control of the pollutant may have no
effect or may even aggravate air quality, we generally believe it is
unreasonable to establish a nationally-applicable presumption that the
pollutant is a regulated NSR pollutant subject to the requirements of
NSR for PM2.5. We discuss our final action with respect to
each of the PM2.5 precursors and the basis for that action
in sections V.A.2 through 5.
For those precursors that are either presumed to be regulated or
not regulated (NOX, VOC, and ammonia), a State program need
not follow the presumed approach if it can be demonstrated that the
precursor in question is not, or is, a ``significant contributor'' to
PM2.5 concentrations within the specific area. ``Significant
contribution'' in this context is a different concept than that in
section 110(a)(2)(D) of the Act. Section 110(a)(2)(D) of the Act
prohibits States from emitting air pollutants in amounts which
significantly contribute to nonattainment or other air quality problems
in other States. Consistent with the previous discussion of sections
189(e) and 302(g), we are clarifying that the use in this NSR
implementation rule of the term ``significant contribution'' to the
area's PM2.5 concentration means that a significant change
in emissions of the precursor from sources in the area would be
projected to provide a significant change in PM2.5
concentrations in the area. For example, if modeling indicates that a
reduction in an area's NOX emissions would reduce ambient
PM2.5 levels in the area, but that a reduction in ammonia
emissions would result in virtually no change in ambient
PM2.5 levels, this would suggest that NOX is a
significant contributor but that ammonia is not. We are not
[[Page 28327]]
establishing in this rule a quantitative test for determining whether
PM2.5 levels in an area change significantly in response to
reductions in precursor emissions in the area. However, in considering
this question, it is relevant to consider that relatively small
reductions in PM2.5 levels are estimated to result in
worthwhile public health benefits.
This approach to identifying a precursor as a regulated NSR
pollutant reflects atmospheric chemistry conditions in the area and the
magnitude of emissions of the precursor in the area. Assessments of
whether it is technically feasible and cost effective to control
particular emissions units at a source should be part of the later BACT
determination within a permit action, and should occur after the basic
assessment of which precursors are to be regulated NSR pollutants in an
area is completed.
Most commenters did not question our legal authority to identify
and regulate PM2.5 precursors. However, some commenters
argued, based on the language of sections 302(g) and 189(e) of the Act,
that once we have designated a compound as a precursor, we do not have
discretion to presumptively exclude it from NSR requirements. Other
commenters on this issue indicated that we do have such discretion,
based on the de minimis doctrine of the Alabama Power decision or on
practical implementation considerations such as the uncertainty in
measuring and modeling the effect of PM2.5 precursors.
We do not agree with the comment that the Act does not give us
discretion to presumptively exclude a PM2.5 precursor from
NSR requirements. As stated previously, we believe that section 302(g)
allows the Administrator to presumptively not require certain
precursors to be addressed in PM2.5 NSR programs generally,
while allowing the State or EPA to make a finding for a specific area
to override the general presumption. In the following pollutant-
specific sections of this preamble, we find that at this time there is
sufficient uncertainty regarding whether certain precursors
significantly contribute to PM2.5 concentrations in all
areas such that the policy set forth in this rule does not
presumptively require certain precursors (ammonia, VOC) to be
controlled in each area. However, the State or EPA may reverse the
presumption and regulate a precursor if it provides a demonstration
showing that the precursor is a significant contributor to
PM2.5 concentrations in the area. In addition, if in the
State's NSR program adoption process a commenter provides additional
information suggesting an alternative policy for regulating a
particular precursor, the State will need to respond to this
information in its rulemaking action.
Hence, we continue to believe that the Act provides us the
authority not only to identify and regulate precursors to
PM2.5, but also to treat precursors of the same pollutant
differently under the same program.
3. Final Action on SO2
Sulfur dioxide is emitted mostly from the combustion of fossil
fuels in boilers operated by electric utilities and other industrial
sources. Less than 20 percent of SO2 emissions nationwide
are from other sources, mainly other industrial processes such as oil
refining and pulp and paper production. The formation of sulfuric acid
from the oxidation of SO2 is an important process affecting
most areas in North America. There are three different pathways for
this transformation.
First, gaseous SO2 can be oxidized by the hydroxyl
radical (OH) to create sulfuric acid. This gaseous SO2
oxidation reaction occurs slowly and only in the daytime. Second, SO2
can dissolve in cloud water (or fog or rainwater), and there it can be
oxidized to sulfuric acid by a variety of oxidants, or through
catalysis by transition metals such as manganese or iron. If ammonia is
present and taken up by the water droplet, then ammonium sulfate will
form as a precipitate in the water droplet. After the cloud changes and
the droplet evaporates, the sulfuric acid or ammonium sulfate remains
in the atmosphere as a particle. This aqueous phase production process
involving oxidants can be very fast; in some cases all the available
SO2 can be oxidized in less than an hour. Third, SO2 can be oxidized in
reactions in the particle-bound water in the aerosol particles
themselves. This process takes place continuously, but only produces
appreciable sulfate in alkaline (dust, sea salt) coarse particles.
Oxidation of SO2 has also been observed on the surfaces of black carbon
and metal oxide particles. During the last 20 years, much progress has
been made in understanding the first two major pathways, but some
important questions still remain about the smaller third pathway.
Models indicate that more than half of the sulfuric acid in the eastern
United States and in the overall atmosphere is produced in clouds.
The sulfuric acid formed from these pathways reacts readily with
ammonia to form ammonium sulfate, (NH4)2SO4. If there is not enough
ammonia present to fully neutralize the produced sulfuric acid (one
molecule of sulfuric acid requires two molecules of ammonia), part of
it exists as ammonium bisulfate; NH4HSO4 (one molecule of sulfuric acid
and one molecule of ammonia) and the particles are more acidic than
ammonium sulfate. In certain situations (in the absence of sufficient
ammonia for neutralization), sulfate can exist in particles as sulfuric
acid, H2SO4. Sulfuric acid often exists in the plumes of stacks where
SO2, sulfur trioxide (SO3), and water vapor are in much higher
concentrations than in the ambient atmosphere, but these concentrations
become quite small as the plume is cooled and diluted by mixing.
Because sulfate is a significant component (e.g., ranging from 9
percent to 40 percent) of PM2.5 concentrations, and contributes to
other air quality problems in all regions of the country, we proposed
to require States to treat SO2 as a PM2.5 precursor in all areas. We
are retaining the same approach for SO2 in this final rule. Sulfate is
an important precursor to PM2.5 formation in all areas, and has a
strong regional impact on PM2.5 concentrations. This approach is
consistent with past EPA regulations, such as the Clean Air Interstate
Rule (CAIR), the Clean Air Visibility Rule, the Acid Rain rules, and
the Regional Haze rule, each of which require SO2 reductions to address
fine particle pollution and related air quality problems. Finally, we
do not believe that regulating SO2 as a precursor to PM2.5 is likely to
add a major burden to sources, as SO2 is already regulated as part of
the NSR program for the SO2 NAAQS.
Most commenters who addressed this issue agreed that SO2 should be
regulated as a PM2.5 precursor, although one only supported regulation
of SO2 as a precursor in NA NSR, and not under PSD. Two commenters
disagreed that SO2 acts as precursors to PM2.5 in all cases and
indicated that it should not be regulated as an ``always-in''
precursor.
We find the commenters' arguments against regulating SO2 as a
precursor unpersuasive. Sulfate is a significant fraction of PM2.5 mass
in all nonattainment areas currently, and although large SO2 reductions
are projected from electric generating units with the implementation of
the CAIR program, sulfate is still projected to be a key contributor to
PM2.5 concentrations in the future, in both attainment and
nonattainment areas. Sulfur dioxide emissions also lead to sulfate
formation on both regional and local scales.
[[Page 28328]]
4. Final Action on NOX
The sources of NOX are numerous and widespread. The combustion of
fossil fuel generates the majority of NOX emissions, with large
contributions from power generation and mobile sources. Nitrates are
formed from the oxidation of NOX into nitric acid (HNO3) either during
the daytime (reaction with OH) or during the night (reactions with
ozone and water). Nitric acid continuously transfers between the gas
and the condensed phases through condensation and evaporation processes
in the atmosphere. However, unless it reacts with other species (such
as ammonia, sea salt, or dust) to form a neutralized salt, it will
volatilize and not be measured using standard PM2.5 measurement
techniques. The formation of aerosol ammonium nitrate is favored by the
availability of ammonia, low temperatures, and high relative humidity.
Because ammonium nitrate is semivolatile and not stable in higher
temperatures, nitrate levels are typically lower in the summer months
and higher in the winter months. The resulting ammonium nitrate is
usually in the sub-micrometer particle size range. Reactions with sea
salt and dust lead to the formation of nitrates in coarse particles.
Nitric acid may be dissolved in ambient aerosol particles.
Based on a review of speciated monitoring data analyses, it is
apparent that nitrate concentrations vary significantly across the
country. For example, in some southeastern locations, annual average
nitrate levels are in the range of 6 to 8 percent of total PM2.5 mass,
whereas nitrate comprises 40 percent or more of PM2.5 mass in certain
California locations. Nitrate formation is favored by the availability
of ammonia, low temperatures, and high relative humidity. It is also
dependent upon the relative degree of nearby SO2 emissions because
ammonia reacts preferentially with SO2 over NOX. Reductions in NOX
emissions are expected to reduce PM2.5 concentrations in most areas.
However, it has been suggested that in a limited number of areas, NOX
control would result in increased PM2.5 mass by disrupting the ozone
cycle and leading to increased oxidation of SO2 to form sulfate
particles, which are heavier than nitrate particles.
Because of these factors, we are finalizing our proposed approach
to NOX as a precursor to PM2.5 for the NSR program. Under this
approach, NOX is presumed to be a significant contributor to ambient
PM2.5 concentrations in all PSD and NA NSR areas. However, a State or
EPA may rebut this presumption for a specific area if the State
demonstrates to the Administrator's satisfaction or EPA demonstrates
that NOX emissions in that area are not a significant contributor to
that area's ambient PM2.5 concentrations. If a State or EPA makes such
a demonstration, NOX would not be considered a PM2.5 precursor under
the NSR program in that area. If a State or EPA does not make such a
demonstration, NOX must be regulated as a precursor under the PSD, NA
NSR, and minor source programs for PM2.5. As discussed previously, this
``presumed-in'' approach is warranted based on the well-known
transformation of NOX into nitrates, coupled with the fact that nitrate
concentrations vary significantly around the country. This approach is
consistent with other recent EPA regulations requiring NOX reductions,
which will reduce fine particle pollution, such as the CAIR and a
number of rules targeting onroad and nonroad engine emissions.
We had proposed that NOX be presumed to be a precursor in any State
that EPA has identified as a source of the PM2.5 interstate transport
problem. In the final rule, we have dropped this requirement to be
consistent with EPA's Clean Air Fine Particle Implementation Rule
published on April 25, 2007. 72 FR 20586. Such a requirement is not
necessary in this rule because States that contribute to downwind
nonattainment for PM2.5 are otherwise required to address transported
NOX emissions under the CAIR.
In areas where NOX is regulated as a precursor to PM2.5, we do not
believe that this is likely to add a major burden to sources, as NOX is
already a regulated NSR pollutant. This is because NOX is an identified
precursor for the ozone NAAQS and an indicator for the NO2 NAAQS.
Several commenters agreed that NOX should be regulated under major
NSR as a precursor to PM2.5. Some of these commenters believe that
States should not have the opportunity to demonstrate otherwise, or
indicated that a waiver for exclusion of NOX as a precursor should be
allowed only if downwind States approve such a waiver. A few commenters
stated that NOX should not be regulated as a precursor to PM2.5 in the
major NSR program, either on grounds of scientific uncertainty
regarding the impact of NOX emissions on ambient PM2.5 concentrations
or on policy grounds (i.e., because NOX is already regulated under NSR
for other NAAQS).
We are not persuaded by the argument that NOX should not be
regulated as a PM2.5 precursor because it is a regulated pollutant
under other NAAQS. We do not find the degree of scientific uncertainty
regarding PM2.5 formation from NOX to be great enough to preclude
regulation of NOX as a precursor with an opportunity for a case-by-case
demonstration that NOX is not a significant contributor. Furthermore,
the fact that we regulate NOX for other NAAQS under the NSR program
does not by itself justify declining to regulate NOX as a PM2.5
precursor in circumstances where NOX also significantly contributes to
PM2.5 formation. As noted earlier, the regulation of NOX as a precursor
for PM2.5 is not expected to add a major burden to regulated sources
that are already required to limit NOX emission to meet other NAAQS.
We disagree with the commenters who believe that emissions of NOX
cannot be correlated to PM2.5 formation, or that it is unclear when NOX
acts as a precursor. As discussed previously, our decision to regulate
NOX as a precursor to PM2.5 is based on the well-known transformation
of NOX into nitrates. Nevertheless, nitrate concentrations vary
significantly across the country. As a result, we believe that the
``presumed-in'' approach is appropriate for NOX since a State can
demonstrate that NOX should not be a precursor in a given area or
region.
While we recognize that NOX emissions can affect PM2.5
concentrations in downwind areas, we disagree that approval from
downwind States should be required for a State to exclude NOX as a
PM2.5 precursor for a particular area. This is because States that
contribute to downwind nonattainment for PM2.5 are otherwise required
to address transported NOX emissions under the CAIR.
5. Final Action on VOC
The organic component of ambient particles is a complex mixture of
hundreds or even thousands of organic compounds. These organic
compounds are either emitted directly from sources (i.e., primary
organic aerosol) or can be formed by reactions in the ambient air
(i.e., secondary organic aerosol, or SOA). Volatile organic compounds
are key precursors in the formation processes for both SOA and ozone.
The relative importance of organic compounds in the formation of
secondary organic particles varies from area to area, depending upon
local emissions sources, atmospheric chemistry, and season of the year.
The lightest organic molecules (i.e., molecules with six or fewer
carbon atoms) occur in the atmosphere mainly as vapors and typically do
not directly
[[Page 28329]]
form organic particles at ambient temperatures due to the high vapor
pressure of their products. However, they participate in atmospheric
chemistry processes resulting in the formation of ozone and certain
free radical compounds (such as OH) which in turn participate in
oxidation reactions to form SOA, sulfates, and nitrates. These VOCs
include all alkanes with up to six carbon atoms (from methane to hexane
isomers), all alkenes with up to six carbon atoms (from ethene to
hexene isomers), benzene, and many low-molecular weight carbonyls,
chlorinated compounds, and oxygenated solvents.
Intermediate weight organic molecules (i.e., compounds with 7 to 24
carbon atoms) often exhibit a range of volatilities and can exist in
both the gas and aerosol phase at ambient conditions. For this reason
they are also referred to as semivolatile compounds. Semivolatile
compounds react in the atmosphere to form SOA. These chemical reactions
are accelerated in warmer temperatures, and studies show that SOA
typically comprises a higher percentage of carbonaceous PM in the
summer as opposed to the winter. The production of SOA from the
atmospheric oxidation of a specific VOC depends on four factors: Its
atmospheric abundance, its chemical reactivity, the availability of
oxidants (ozone, OH, HNO3), and the volatility of its products. In
addition, recent work suggests that the presence of acidic aerosols may
lead to an increased rate of SOA formation. Aromatic compounds such as
toluene, xylene, and trimethyl benzene are considered to be the most
significant anthropogenic SOA precursors and have been estimated to be
responsible for 50 to 70 percent of total SOA in some airsheds. Man-
made sources of aromatics gases include mobile sources, petrochemical
manufacturing, and solvents. Some of the biogenic hydrocarbons emitted
by trees are also considered to be important precursors of secondary
organic PM. Terpenes (and b-pinene, limonene, carene, etc.) and the
sesquiterpenes are expected to be major contributors to SOA in areas
with significant vegetation cover, but isoprene is not. Terpenes are
very prevalent in areas with pine forests, especially in the
southeastern United States. The rest of the anthropogenic hydrocarbons
(higher alkanes, paraffins, etc.) have been estimated to contribute 5
to 20 percent to the SOA concentration depending on the area.
The contribution of the primary and secondary components of organic
aerosol to the measured organic aerosol concentrations remains a
complex issue. Most of the research performed to date has been done in
southern California, and more recently in central California, while
fewer studies have been completed on other parts of North America. Many
studies suggest that the primary and secondary contributions to total
organic aerosol concentrations are highly variable, even on short time
scales. Studies of pollution episodes indicate that the contribution of
SOA to the organic PM can vary from 20 percent to 80 percent during the
same day.
Despite significant advances in understanding the origins and
properties of SOA, it remains probably the least understood component
of PM2.5. The reactions forming secondary organics are complex, and the
number of intermediate and final compounds formed is voluminous. Some
of the best efforts to unravel the chemical composition of ambient
organic aerosol matter have resulted in quantifying the concentrations
of hundreds of organic compounds representing only 10 to 20 percent of
the total organic aerosol mass. For this reason, SOA continues to be a
significant topic of research and investigation.
Current scientific and technical information shows that
carbonaceous material is a significant fraction of total PM2.5 mass in
most areas, that certain VOC emissions are precursors to the formation
of SOA, and that a considerable fraction of the total carbonaceous
material originates from local as opposed to regional sources. However,
while significant progress has been made in understanding the role of
gaseous organic material in the formation of organic PM, this
relationship remains complex. We recognize that further research and
technical tools are needed to better characterize emissions inventories
for specific VOC, and to determine the extent of the contribution of
specific VOC to organic PM mass.
As a result, this final rule does not, in general, require
regulation of VOC as a precursor to PM2.5 for the NSR program. However,
a State may demonstrate to the Administrator's satisfaction or EPA may
demonstrate that VOC emissions in a specific area are a significant
contributor to that area's ambient PM2.5 concentrations. After such a
demonstration, the State would regulate VOC (or a subset of VOC) as a
PM2.5 precursor for the NSR program in that area. That is, the State
would need to regulate construction and modification of stationary
sources that increase emissions of VOC in that area to assure that
these emissions do not interfere with reasonable further progress or
the ability of that area to attain or maintain the PM2.5 NAAQS.
We believe that this ``presumed-out'' approach is appropriate for
VOC because of the complexity in assessing the role of VOC in PM2.5
formation, as discussed previously. Where the effect of a pollutant's
emissions on ambient PM2.5 concentrations is subject to this degree of
uncertainty, we do not have justification to establish a nationally-
applicable presumption that the pollutant is a regulated NSR pollutant
subject to the requirements of NSR for PM2.5. Under the circumstances,
we believe the best policy is to continue to regulate VOC under NSR as
a precursor to ozone in all areas, which will potentially provide a co-
benefit for PM2.5 concentrations despite the uncertainty in PM2.5
formation from VOC. As discussed previously, we do not find it
appropriate to utilize the same approach for NOX because the scientific
data and modeling analyses provide more certainty that NOX emissions
are a significant contributor to ambient PM2.5 concentrations.
Note that we intend to regulate high molecular weight VOC (with 25
carbon atoms or more and low vapor pressure) as direct PM2.5 emissions
because they are emitted directly as primary organic particles and
exist primarily in the condensed phase at ambient temperatures. See
section V.E following for more on the regulation of such
``condensables.''
Most commenters agreed with the ``presumed-out'' approach for VOC.
One commenter said that the role of VOC in the formation of PM2.5 is
sufficiently understood to recommend a ``waiver'' approach for this
pollutant in the same way as NOX is treated for PM2.5 in the rule.
As discussed previously, the reactions forming secondary organics
are complex and the number of intermediate and final compounds formed
is voluminous. Some of the best efforts to unravel the chemical
composition of ambient organic aerosol matter have merely been able to
quantify the concentrations of hundreds of organic compounds
representing only 10 to 20 percent of the total organic aerosol mass.
For this reason, SOA continues to be a significant topic of research
and investigation. Accordingly, we do not agree with the commenter who
suggested a waiver or ``presumed-in'' approach for VOC. We continue to
believe that our ``presumed-out'' approach is most appropriate for VOC
and have included this approach in the final rules.
[[Page 28330]]
6. Final Action on Ammonia
Ammonia (NH3) is a gaseous pollutant that is emitted by natural and
anthropogenic sources. Emissions inventories for ammonia are considered
to be among the most uncertain of any species related to PM. Ammonia
serves an important role in neutralizing acids in clouds,
precipitation, and particles. In particular, ammonia neutralizes
sulfuric acid and nitric acid, the two key contributors to acid
deposition (acid rain). Deposited ammonia also can contribute to
problems of eutrophication in water bodies, and deposition of ammonium
particles may effectively result in acidification of soil as ammonia is
taken up by plants. The NARSTO Fine Particle Assessment \8\ indicates
that reducing ammonia emissions where sulfate concentrations are high
may reduce PM2.5 mass concentrations, but may also increase the acidity
of particles and precipitation. An increase in particle acidity is
suspected to be linked with adverse human health effects and with an
increase in the formation of secondary organic compounds. Based on this
information and further insights gained from the NARSTO Fine Particle
Assessment, it is apparent that the formation of particles related to
ammonia emissions is a complex, nonlinear process.
---------------------------------------------------------------------------
\8\ NARSTO (2004) ``Particulate Matter Assessment for Policy
Makers: A NARSTO Assessment.'' P. McMurry, M. Shepherd, and J.
Vickery, eds. Cambridge University Press, Cambridge, England. ISBN 0
52 184287 5. See the docket for this rulemaking, Docket ID No. EPA-
HQ-OAR-2003-0062, or http://www.narsto.org/section.src?SID=6.
---------------------------------------------------------------------------
Though recent studies have improved our understanding of the role
of ammonia in aerosol formation, ongoing research is required to better
describe the relationships between ammonia emissions, PM
concentrations, and related impacts. The control techniques for ammonia
and the analytical tools to quantify the impacts of reducing ammonia
emissions on atmospheric aerosol formation are both evolving. Also,
area-specific data are needed to evaluate the effectiveness of reducing
ammonia emissions on reducing PM2.5 concentrations in different areas,
and to determine where ammonia decreases may increase the acidity of
particles and precipitation.
Due to the considerable uncertainty related to ammonia as a
precursor, our final rules do not require ammonia to be regulated as a
PM2.5 precursor but do give States the option to regulate ammonia as a
precursor to PM2.5 in nonattainment areas for purposes of NSR on a
case-by-case basis. Consistent with our proposal, if a State
demonstrates to the Administrator's satisfaction that ammonia emissions
in a specific nonattainment area are a significant contributor to that
area's ambient PM2.5 concentrations, the State would regulate ammonia
as a PM2.5 precursor under the NSR program in that nonattainment area.
Once this demonstration is made, ammonia would be a ``regulated NSR
pollutant'' under NA NSR for that particular nonattainment area, and
the State would need to regulate construction and modification of
stationary sources that increase emissions of ammonia in that area to
assure that these emissions do not interfere with reasonable further
progress or the ability of that area to attain or maintain the PM2.5
NAAQS. In all other nonattainment areas in that State and nationally,
ammonia would not be subject to the NSR program. In addition, the
action of any State identifying ammonia emissions as a significant
contributor to a nonattainment area's PM2.5 concentrations, or our
approval of a nonattainment SIP doing so, does not make ammonia a
regulated NSR pollutant for the purposes of PSD in any attainment or
unclassifiable areas nationally. This is consistent with our proposal
(70 FR 66036) and no commenters took issue with the proposal. We also
retain the ability to make a technical demonstration for any area in a
State, if appropriate, to reverse the presumption and require ammonia
to be addressed in that State's nonattainment area plan.
We elected to finalize the proposed approach because of continued
uncertainties regarding ammonia emission inventories and the effects of
ammonia emission reductions. Ammonia emission inventories are presently
very uncertain in most areas, complicating the task of assessing
potential impacts of ammonia emissions reductions. In addition, data
necessary to understand the atmospheric composition and balance of
ammonia and nitric acid in an area are not widely available, making it
difficult to predict the results of potential ammonia emission
reductions. Ammonia reductions may be effective and appropriate for
reducing PM2.5 concentrations in selected locations, but in other
locations such reductions may lead to minimal reductions in PM2.5
concentrations and increased atmospheric acidity. Research projects
continue to expand our collective understanding of these issues, but at
this time we believe this case-by-case approach for nonattainment areas
is appropriate given that there is sufficient uncertainty regarding the
impact of ammonia emission reductions on PM2.5 concentrations in all
nonattainment areas. In light of these uncertainties, we encourage
States to continue efforts to better understand the role of ammonia in
their fine particle problem areas.
Several commenters agreed with our ``presumed-out'' approach for
ammonia. One of these commenters recommended that we recognize the role
ammonia plays in PM2.5 formation and develop a policy to require the
minimization and mitigation of known emissions of ammonia, while
another suggested that we require States to initiate comprehensive
ambient air monitoring networks to determine the extent of local
effects of ammonia.
Four commenters did not support treating ammonia as a PM2.5
precursor under any circumstances. Three of these commenters stated
that if EPA permits States to demonstrate that ammonia should be
regulated as a PM2.5 precursor for NSR purposes, we should make clear
that ammonia emissions from the operation of an air pollution control
system to control NOX should not factor into such a demonstration.
Two commenters preferred that we use the ``presumed-in'' approach
for ammonia, as for NOX. One of these commenters stated that the
``presumed-out'' approach would improperly delegate our authority to
regulate ammonia as a PM2.5 precursor to the States and would reverse
Congress' requirement to regulate PM precursors unless the emissions
are not part of the problem, instead taking the approach that we will
``not regulate unless proven to be part of the problem.''
We continue to believe that the ``presumed-out'' approach is most
appropriate for ammonia. As discussed previously, considerable
uncertainties remain regarding ammonia emission inventories and the
effects of ammonia emission reductions. As a result, we do not believe
it advisable to adopt a ``presumed-in'' approach. However, where a
State can gather sufficient data to demonstrate that reductions in
ammonia emissions will decrease ambient concentrations of PM2.5 in a
particular nonattainment area, we believe that the State should be
allowed to regulate ammonia emissions under its PM2.5 NSR program for
that area.
We do not believe that this approach improperly delegates authority
to the States. The final rule establishes a general presumption for all
nonattainment areas through this rulemaking process, and allows for the
presumption to be modified by the State on a case-by-case basis with
EPA approval. Under the Clean Air Fine
[[Page 28331]]
Particle Implementation Rule (72 FR 20586, April 5, 2007) (addressing
various nonattainment plan elements other than NSR), we still retain
the ability to make a technical demonstration for any area if
appropriate to reverse the presumption and require ammonia to be
addressed in its nonattainment area plan. As discussed previously in
section V.A.1, we interpret the Act to allow the ``presumed-out''
approach adopted in the final rule.
We agree with the commenter who suggested that we continue research
on the role of ammonia in the formation of PM2.5. We believe that it is
prudent to continue research on ammonia control technologies and the
ammonia-sulfate-nitrate-SOA equilibrium before undertaking a broad
national program to reduce ammonia emissions. As we develop a greater
understanding about the potential air quality effects of reducing
ammonia emissions in specific nonattainment areas, it may be
appropriate for ammonia reduction strategies to be included in future
SIPs. At this time, however, we believe that reducing SO2 and NOX
emissions will achieve significant reductions in ambient PM2.5
concentrations.
Regarding the comment related to ammonia emissions from NOX control
systems, we believe that a State should evaluate all sources of ammonia
emissions when determining whether to regulate ammonia under its PM2.5
NSR program for a particular nonattainment area. However, we also
encourage States to be mindful of the potential tradeoff in terms of
ambient PM2.5 concentrations that may be related to reducing ammonia
emissions from NOX control systems.
B. Major Stationary Source Threshold for PM2.5
The major NSR program applies to construction of major stationary
sources and major modifications at major stationary sources. A
stationary source is a ``major source'' if its actual emissions or its
potential to emit for a specific pollutant equals or exceeds the major
source threshold for that pollutant established in the Act. Different
pollutants, including precursors, are not summed to determine
applicability.
Sections 169 and 302(j) of the Act contain definitions of ``major
emitting facility'' and ``major stationary source'' that apply to
programs implemented under part C and subpart 1 of part D of the Act
(PSD and NA NSR, respectively). Consistent with our proposal, these
final rules follow these definitions for purposes of defining a major
emitting facility or major stationary source that would be subject to
major NSR. The thresholds set out in the definitions are applied to
each relevant pollutant individually, that is, to direct PM2.5
emissions and to emissions of each pollutant identified as a PM2.5
precursor for the applicable NSR program. Under the final rules, the
major source thresholds are as follows:
------------------------------------------------------------------------
------------------------------------------------------------------------
PSD................................. 100 tpy for source categories
listed in 40 CFR
51.166(b)(1)(i)(a) and
52.21(b)(1)(i)(a).
250 tpy for all other source
categories.
NA NSR.............................. 100 tpy for all source categories.
------------------------------------------------------------------------
No regulatory change is required to implement this approach to the
major source thresholds for direct PM2.5 emissions and the PM2.5
precursors. See 40 CFR 51.165(a)(1)(iv)(a), 51.166(b)(1)(i),
52.21(b)(1)(i), and part 51, appendix S, section II.A.4.
This approach is consistent with how we treat other criteria
pollutants that are covered by subpart 1 of part D of the Act.
Nonattainment NSR programs under subpart 1 do not include a tiered
classification system such as the one required for ozone nonattainment
areas under subpart 2 of part D. We do not interpret subpart 4 of part
D of the Act (creating ``serious'' and ``moderate'' classifications for
PM10 nonattainment areas) as applying to PM2.5.
Although our approach is consistent with sections 169 and 302(j)
and subpart 1 of part D of the Act, it results in a higher major source
threshold in PM2.5 nonattainment areas than the major source
threshold that applies in some PM10 nonattainment areas
under subpart 4 of part D of the Act. This is because section 189(b) of
the Act establishes a 70-tpy major source threshold for ``serious''
PM10 nonattainment areas while ``moderate'' PM10
nonattainment areas apply a 100-tpy major source threshold based on the
definition in section 302(j). We do not believe the Act gives us the
discretion to promulgate a lower major source threshold for pollutants
such as PM2.5 that are only subject to subpart 1 of part D
of the Act.
Our emissions inventory data do not indicate that this situation
will adversely impact attainment of the PM2.5 NAAQS. These
data indicate that a significant number of sources have actual
PM2.5 emissions in the 100 to 250 tpy range. Additionally,
our more current inventory data show that the number of sources that
would be covered as major sources by a lower major source threshold
would not increase substantially unless the threshold were lowered to
20 tpy or below. Thus, even if EPA had the discretion to adopt a 70-tpy
major source threshold for PM2.5 nonattainment areas, our
data indicate that few additional sources would be subject to the major
NSR program in PM2.5 nonattainment areas.\9\
---------------------------------------------------------------------------
\9\ See ``NEI-PM2.5 Source Analysis'' in the docket
for this rulemaking, Docket ID No. EPA-HQ-OAR-2003-0062.
---------------------------------------------------------------------------
We believe that States should consider such information in
developing their own SIP-approved NSR programs. For example, if
construction of PM2.5 sources emitting 99 tpy with no major
NSR controls and without mitigation would undermine a State's ability
to achieve reasonable further progress or attain the PM2.5
NAAQS, the State should consider imposing emissions controls or other
requirements on these sources through the State's minor NSR program.
Note that such programs are required under the existing statute and
regulations to assure that the NAAQS are achieved. See section
110(a)(2)(C) of the Act and 40 CFR 51.160. In addition, States may
address such sources through other elements in their nonattainment area
SIPs that are not statutorily bound to the definition of major source,
as the major NSR program is. We reiterate that since we do not
interpret subpart 4 of the Act to apply to PM2.5, we do not
believe that we have discretion under section 302(j) of the Act to
define a lower major source threshold for pollutants such as
PM2.5 that are only subject to subpart 1 of part D of the
Act.
Some commenters indicated that State minor NSR programs would not
be sufficient to address such sources due to interstate transport and
the existence of interstate PM2.5 nonattainment areas. These
commenters indicated that a lower major source threshold for
PM2.5 sources located in designated nonattainment areas
should be applied uniformly throughout the entire nonattainment area,
which would not be possible when minor NSR programs are defined on a
State-by-State basis.
We believe, to the contrary, that States can coordinate their minor
NSR programs to address interstate PM2.5 nonattainment
areas, and we encourage them to do so. In addition, we note that the
impacts of direct PM2.5 emissions are generally felt
primarily in the local area.
One commenter stated that in order to address the impact of high PM
concentrations, the Act mandates EPA to define a criteria pollutant's
NSR major threshold at levels less than 100 tpy. The commenter gave the
example of
[[Page 28332]]
subparts 2 and 4 of part D of the Act, which define lower major source
thresholds for certain classifications of ozone and PM10
nonattainment areas, respectively. The commenter argued that it is
unreasonable for us to assert that subpart 4 does not apply to this
rule because it regulates all PM with a diameter of less than 10
micrometers, which includes PM2.5. The commenter believes
that we recognized as much in our proposal preamble discussion of the
options for implementing reasonably available control technology
(RACT), where we discussed potential approaches that ``would be
consistent with the approach set forth in the Act in subpart 4.'' 70 FR
66017. This commenter stated that a reasonable interpretation of the
Act requires major sources of direct PM2.5 emissions and
precursor emissions to be defined at a baseline level of 70 tpy, and
adjusted further downward as appropriate considering the
characteristics and potential impacts of the pollutants.
We do not agree that subpart 4 of part D applies to
PM2.5 nonattainment areas. Subpart 4 was added to the Act by
Congress specifically to address the PM10 NAAQS. We believe
that the PM2.5 standard should be implemented under subpart
1 of part D, which is the general provision of the Act related to NAAQS
implementation. Part D of title I of the Act sets forth the
requirements for SIPs needed to attain the NAAQS. Part D also includes
a general provision under subpart 1, which applies to all NAAQS for
which a specific subpart does not exist. Because the PM2.5
standards were not established until 1997, the nonattainment plan
provisions found in section 172 of subpart 1 apply. Subpart 4 on its
face applies only to the PM10 standard. In general, the
emphasis in subpart 4 on reducing PM10 concentrations from
certain sources of direct PM2.5 emissions can be somewhat
effective in certain PM2.5 nonattainment areas but not in
all. Contributions to PM2.5 concentrations are typically
from a complex mix of sources of primary emissions and sources of
precursor emissions, which form particles through reactions in the
atmosphere. In addition, PM2.5 differs from PM10
in terms of atmospheric dispersion characteristics, chemical
composition, and contribution from regional transport.
A group of environmental commenters believed that EPA should be
consistent with the stationary source size thresholds proposed for RACT
in option 2, see 70 FR 66019/1. In our proposal preamble discussion of
RACT, while we discussed developing a classification system for
PM2.5 nonattainment areas under section 172(a)(1) of subpart
1, we did not discuss subjecting PM2.5 to the requirements
of subpart 4. While our discussion of RACT contemplated a lower
threshold for RACT applicability in some PM2.5 nonattainment
areas, we did not characterize this as defining a lower major source
threshold. Moreover, section 302(j) defines a major stationary source
as one that emits 100 tpy or more ``except as otherwise expressly
provided.'' Since section 172 does not expressly provide EPA with the
authority to promulgate a major source threshold below 100 tpy, we do
not believe we are authorized to do so under subpart 1 of part D of the
Act.
One commenter stated that the major source threshold for
PM2.5 emissions should be calculated using the current
SO2 and NOX definitions of major source and
significant emissions rate. Specifically, the commenter suggested that
the ratio of these values (100 tpy and 40 tpy, respectively) should be
multiplied by the significant emissions rate for direct
PM2.5 emissions (10 tpy; see section V.C following) to yield
a PM2.5 major source threshold of 25 tpy.
As previously stated, we do not believe that we have discretion
under the Act to define a lower major source threshold under subpart 1
of part D of the Act. In any case, the major source thresholds and
significant emissions rates for SO2 and NOX were
not defined in relation to one another, and therefore their
relationship would not provide a suitable basis for developing the
PM2.5 major source threshold from the PM2.5
significant emissions rate. Major source thresholds are defined
directly in the Act, while the significant emissions rates were
codified independently in regulations through a modeling analysis of
ambient impacts.
C. Significant Emissions Rate for Direct Emissions of PM2.5
The determination of what should be classified as a modification
subject to major NSR is based, in part, on a ``significant emissions
rate.'' \10\ The major NSR regulations define this term as a rate above
which a net emissions increase will trigger major NSR permitting
requirements, if the increase results from a major modification.
Sources are exempt from major NSR requirements if the emissions
increase resulting from a modification is below this rate because EPA
considers such lower emissions increases to be de minimis for purposes
of the major NSR program.
---------------------------------------------------------------------------
\10\ For additional background on EPA's interpretation of
modification and rationale for including significant emissions rates
in defining major modifications, see 61 FR 38253-54 (Dec. 31, 2002).
---------------------------------------------------------------------------
The significant emissions rates for the criteria pollutants other
than PM2.5 are given in the following table:
------------------------------------------------------------------------
Criteria pollutant Significant emissions rate (tpy)
------------------------------------------------------------------------
Ozone........................ VOC: Any increase up to 40 tpy (dependent
on NA classification).
NOX: Any increase up to 40 tpy (dependent
on NA classification).
NO2.......................... NOX: 40 tpy.
Particulate Matter........... 25 tpy, particulate matter emissions.
15 tpy, PM10 emissions.
CO........................... 50 or 100 tpy (dependent on NA
classification).
SO2.......................... 40 tpy.
Lead......................... 0.6 tpy.
------------------------------------------------------------------------
Significant emissions rates for additional (non-criteria) pollutants
that are subject to the PSD program are contained in 40 CFR
51.166(b)(23) and 40 CFR 52.21(b)(23).
For direct emissions of PM2.5, these final rules define
the significant emissions rate as 10 tpy. This is the level that we
proposed as our preferred option. This final significant emissions rate
for direct PM2.5 emissions is based fundamentally on the
same approach that we used in setting the previous significant
emissions rates for PM emissions and PM10 emissions.
Historically, the original significant emissions rate for PM (25
tpy of PM emissions) was set using a modeling analysis to determine the
amount of PM emissions that a source could emit that
[[Page 28333]]
would be unlikely to cause ambient impacts above 4 percent of the PM
NAAQS (measured as total suspended particulate (TSP)).\11\ Although a
range of source configurations can yield a wide range of impacts per
tpy of emissions, our review of typical configurations of major PM
sources led us to the conclusion that a major modification that
increased PM emissions by 25 tpy or less would be unlikely to increase
24-hour average concentrations of TSP by more than 4 percent of the 24-
hour TSP NAAQS. Subsequently, when we set the significant emissions
rate for PM10, we adjusted the rate for PM emissions using
the ratio of the 24-hour PM10 NAAQS to the 24-hour TSP NAAQS
to derive the PM10 significant emissions rate of 15 tpy. We
used the ratio of 24-hour NAAQS for this adjustment because that NAAQS
was controlling for both PM and PM10.
---------------------------------------------------------------------------
\11\ The EPA established the original NAAQS for PM in terms of
ambient concentrations of TSP (40 CFR 51.100(ss)). Source
applicability for PM was determined in terms of amounts of PM
emissions (40 CFR 51.100(pp)) from the affected source. In 1993, at
58 FR 31622 (see page 31629), EPA eliminated TSP as the ambient
indicator for measuring compliance with both the NAAQS and PSD
increments. Thus, EPA no longer considers the TSP ambient indicator
to be a regulated NSR pollutant. The EPA is currently evaluating
whether it remains appropriate to consider PM as a ``regulated NSR
pollutant.'' There is no NAAQS for TSP/PM, rather the standards
address specific size fractions of PM, namely PM10 and
PM2.5. However, PM emissions, based on in-stack
measurements, continue to be regulated under PSD because of the use
of such emissions for evaluating compliance under a variety of CAA
section 111 new source performance standards (40 CFR part 60). Given
the regulatory changes and positions taken by EPA since 1993, EPA is
re-evaluating the implications for PM emissions in the NSPS program
(and other air programs) and will act accordingly to clarify this
issue in the near-term.
---------------------------------------------------------------------------
We used a conceptually similar methodology to derive the final
PM2.5 significant emissions rate from the rate for
PM10. However, because the 24-hour NAAQS is not controlling
for PM2.5, we revised the methodology to take into account
the annual impact of emissions. See the proposal preamble for
additional information on the methodology we used to develop the final
significant emissions rate for direct PM2.5 emissions (70 FR
66038).
Several commenters supported our approach to setting the
significant emissions rate for direct PM2.5 emissions and
the level (10 tpy) based on the same methodology used for PM emissions
and PM10 emissions. Numerous other commenters believe that
our methodology was too conservative, and suggested a significant
emissions rate of 15 tpy. Two commenters suggested that we use
significant emissions rate of 5 tpy or less. Another commenter
suggested that we could ``split the difference,'' using an option that
could give States and companies some flexibility: Modifications less
than 5 tpy of direct PM2.5 emissions could be considered de
minimis; modifications between 5 and 15 tpy of direct PM2.5
emissions could choose to either demonstrate less than a 4 percent
NAAQS increase or simply be subject; and modifications with increases
of 15 or more tpy of direct PM2.5 emissions would be
subject.
We agree with commenters who indicated that we were correct in
using the same methodology for direct PM2.5 that was used to
set the significant emissions rate for PM10 and PM
emissions. We do not agree that using the same level as PM10
emissions (15 tpy) is warranted, given the demonstrated health effects
of PM2.5. Neither do we agree that a significant emissions
rate of 5 tpy or less is warranted. While our screening model runs
indicated that emissions increases in this range at facilities with
short stacks can cause measurable increases in ambient PM2.5
levels, we do not believe that facilities at the extremes should
dictate the program for all sources.
We do not agree that inclusion of condensable emissions in future
testing and applicability determinations (see section V.E) is grounds
for increasing the SER for direct PM2.5 emissions. The
results of the modeling analysis that is the basis for the SER of 10
tpy is not affected by the nature of the direct PM2.5
emissions (i.e., condensable or not).
We also do not agree that the proportions of primary and secondary
PM2.5 that comprise ambient PM2.5 concentrations
is relevant to determining the appropriate SER for direct
PM2.5 emissions. Following our historic approach for PM and
PM10, we based our analysis on determining the size of a
source of direct PM2.5 emissions that would be expected to
have an ambient impact of 4 percent or more of the NAAQS. This
relationship holds true regardless of the origin of the particles that
make up the ambient PM2.5. The commenter's approach (i.e.,
carrying out the analysis based on one-half of the NAAQS because
primary PM2.5 makes up only one-half of the ambient
PM2.5) implies that an increase in ambient PM2.5
concentrations due to an increase in direct PM2.5 emissions
is somehow automatically matched by a like increase in the ambient
concentration of secondary PM2.5. We do not believe that
this is a reasonable approach.
D. Significant Emissions Rates for PM2.5 Precursors
Consistent with the preferred option in the proposal, we are
setting significant emissions rates for PM2.5 precursors at
the levels for those pollutants already included in major NSR programs,
as shown in the following table:
------------------------------------------------------------------------
Significant emissions rate
PM2.5 precursor (equal to or exceeding)
------------------------------------------------------------------------
SO2....................................... 40 tpy.
NOX....................................... 40 tpy.
VOC....................................... 40 tpy.
Ammonia................................... Adopted in SIP.
------------------------------------------------------------------------
VOC is presumed not to be a precursor to PM2.5 in any
attainment or unclassifiable area, unless the State demonstrates to the
Administrator's satisfaction or EPA demonstrates that emissions of VOC
from sources in a specific area are a significant contributor to that
area's ambient PM2.5 concentrations. Any State making such a
demonstration would be required to adopt the 40-tpy significant
emissions rate unless it demonstrates that a more stringent significant
emissions rate (lower rate) is more appropriate.
For ammonia, States determining in their SIPs that control of
ammonia is a necessary part of a PM2.5 control strategy in a
particular area must set the significant emissions rate for ammonia.
Otherwise, according to the definition of ``significant'' in the PSD
program, ``any emissions rate'' would be considered significant. See 40
CFR 51.166(b)(23)(ii).
One commenter stated that we should not leave it to States to set
significant emissions rates for ammonia. The commenter argued that
EPA's scientists should shoulder this responsibility, and the resulting
significant emissions rate should be subject to notice and comment.
In the final rule, we are allowing those States that determine in
their SIPs that control of ammonia is necessary to set the significant
emissions rate for ammonia, based on the information developed for each
attainment demonstration. At this time, we believe this is more
appropriate than EPA setting a single, nationwide significant emissions
rate because of the different role ammonia plays in the formation of
PM2.5 from one area to another, as well as our still-
evolving understanding of the impact of reducing ammonia emissions on
ambient PM2.5 concentrations. In addition, we note that the
SIP revisions that States undertake to add ammonia to their NA NSR
[[Page 28334]]
programs are subject to notice and comment rulemaking procedures.
Numerous commenters supported our proposal to set significant
emissions rates for PM2.5 precursors at the levels already
used for other purposes in the NSR program. One commenter indicated
that since roughly half or more of ambient PM2.5 is derived
from precursors, 10 tpy would be an appropriate significant emissions
rate for PM2.5 precursor emissions. Another commenter
suggested a significant emissions rate of 4 tpy for SO2 and
2 tpy for NOX, based on the percentage of PM2.5
that is typically derived from these precursors and the ratios between
the existing significant emissions rates for these pollutants and the
SO2 and NO2 annual NAAQS. Since the ambient
concentrations of PM2.5 vary across the country and since
significant emissions rates have not been developed as a ratio of the
NAAQS, we do not believe that the suggested approach is appropriate.
As discussed in the proposal, the use of existing significant
emission rates where the PM2.5 precursor is also regulated
under NSR as a separate criteria pollutant harmonizes the NSR program
for PM2.5 with the NSR programs for those other criteria
pollutants. This enables a source to determine the NSR impacts of
proposed modifications by reference to a single significant emissions
rate for each pollutant, and enables streamlining of determinations
regarding the applicable control technology and analysis of air quality
impacts into a single and comprehensive decision making process for
both PM2.5 and other criteria pollutants that also cover
PM2.5 precursors. This also follows precedent. When ozone
became a criteria pollutant, EPA used the NOX significant
emissions rate from the NO2 program.
The burden imposed is not the only factor to consider when setting
the significant emission rates for precursors--the process for
determining the significant emission rates must also take into account
the accuracy and certainty with which we can predict the effect of the
precursors on PM2.5 concentrations. It is difficult to
determine the ambient air quality effects that result from a single
source of emissions of PM2.5 precursors. There are
conservative screening models for predicting impacts of large
NOX and SO2 sources on ambient PM2.5
concentrations. We conducted a range of modeling analyses to determine
the amount of PM2.5 precursor emissions needed to show an
increase in ambient PM2.5 concentrations. These analyses
showed that precursor emissions probably have some localized impacts,
but that most impact is farther downwind as precursors have the time to
convert to PM2.5. In addition, the modeling available at
this time does not provide sufficient information to estimate impacts
of emissions from individual sources of ammonia and VOC on ambient
PM2.5 concentrations. While we know that precursors
contribute to the formation of PM2.5 in the ambient air, the
degree to which these individual precursors contribute to
PM2.5 formation in a given location is complex and variable.
There are competing chemical reactions taking place in the atmosphere,
and meteorological conditions play a significant role in the size and
characteristics of particle formation. For these reasons, we do not
believe that we have adequate data on the impacts of precursor
emissions from individual sources to override the administrative
advantages of setting the significant emissions rates for
SO2, NOX, and VOC for purposes of the
PM2.5 NSR program at the same levels that are already used
for other purposes in the major NSR program.
E. Condensable PM Emissions
In this final NSR rule, EPA will not require that States address
condensable PM in establishing enforceable emissions limits for either
PM10 or PM2.5 in NSR permits until the completion
of a transition period, as described herein. In response to significant
comments on the variability of test methods available for measuring
condensable emissions, we have adopted this transition period approach
to allow us to assess the capabilities of the test methods and possibly
revise them to improve performance. The transition period will end
January 1, 2011 unless EPA advances this date through the rulemaking
process described below.
Subsequent to the completion of the test methods assessment, EPA
will be conducting a notice and comment rulemaking to codify new or
revised test methods. Once these new or revised test methods are in
place, States will have the tools necessary to issue NSR permits
addressing condensable PM. Thus, as part of the test methods
rulemaking, we will take comment on an earlier closing date for the
transition period in the NSR program if we are on track to meet our
expectation to complete the test methods rule much earlier than January
1, 2011. In the meantime, however, we are establishing January 1, 2011
as the latest possible end date for the NSR transition period because
this is also the end of the transition period for SIP purposes as
described in the Clean Air Fine Particle Implementation Rule (see
section II.L in 72 FR 20586, April 25, 2007). Prevention of Significant
Deterioration and NA NSR permits issued after the effective date of
this NSR implementation rule but prior to the end of the transition
period for the NSR program are not required to account for condensable
emissions in PM2.5 or PM10 emissions limits.
After January 1, 2011 (or any earlier date established in the upcoming
rulemaking codifying test methods), EPA will require that NSR permits
include limits of condensable emissions, as appropriate. Prior to this
date, States are not prohibited from establishing emissions limits in
NSR permits that include the condensable fraction of direct
PM2.5.
As noted in the proposal preamble, certain commercial or industrial
activities involving high temperature processes (e.g., fuel combustion,
metal processing, and process cooking operations) emit gaseous
pollutants into the ambient air, some of which rapidly condense into
particle form. The constituents of these condensed particles include,
but are not limited to, organic materials, sulfuric acid, and metals
and metal compounds. We consider such condensable emissions to be a
component of direct PM emissions. Specifically, direct PM emissions
consist of both the ``filterable fraction'' which already exist in
particle form at the elevated temperature of the exhaust stream, and
the ``condensable fraction'' which exist in gaseous form under exhaust
stream conditions but condenses rapidly in the ambient air.
Because condensable PM emissions exist almost entirely in the 2.5
micrometer range and smaller, these emissions are inherently more
significant for PM2.5 than for prior PM standards addressing
larger particles. Condensable PM emissions commonly make up a
significant component of direct PM2.5 emissions. Therefore,
we believe that it is important that the air quality management of PM
promote a comprehensive approach to the control of condensable PM.
We proposed on November 1, 2005 to clarify that condensable PM
emissions must be included when determining whether a source is subject
to the major NSR program. We noted in the proposal that our prior
guidance \12\ had clarified that PM10 includes condensable
PM and
[[Page 28335]]
that, where States expect condensable PM emissions to be in higher
amounts, States should use methods that appropriately measure
condensable PM emissions. In addition, we pointed out that the 2001
consolidated emissions reporting rule (CERR) requires States to report
condensable emissions in each inventory revision (see 67 FR 39602, June
10, 2001) and that Method 202 in appendix M of 40 CFR part 51
quantifies condensable PM. We also noted that States have not applied
this existing guidance consistently.
---------------------------------------------------------------------------
\12\ Leter from Thompson G. Pace, Acting Chief, Particulate
Matter Programs Branch, to Sean Fitzsimmons, Iowa Department of
Natural Resources (Mar. 31, 1994) (available at http://www.epa.gov/Region7/programs/artd/air/nsr.nsrmemos/cpm.pdf and in the docket for
this rulemaking, Docket ID No. EPA-HQ-OAR-2003-0062).
---------------------------------------------------------------------------
We received a number of comments on whether NSR programs should
account for condensable PM emissions in light of the current state of
knowledge of and uncertainties around the measurement of direct
PM2.5. Several commenters supported our proposal to require
the inclusion of condensable PM emissions in NSR applicability
determinations. On the other hand, several other commenters expressed
opposition to including condensables at this time and raised concerns
about the availability and implementation of test methods and related
issues about the uncertainties in existing data for condensable
PM2.5. As a result of the concerns, these commenters
believed EPA would be premature in requiring a comprehensive evaluation
of condensable PM2.5, especially as it related to developing
any new emissions limits for stationary sources.
One commenter noted that regulation of condensable PM at this time
will impede, rather than facilitate, expeditious attainment of the
PM2.5 standard. Another commenter expressed concern about
the potential for retroactive enforcement over applicability decisions
made in good faith, and for retroactive application of the new test
method to assert violations of an emission limit, where the
applicability decision or the emission limit was originally based on
flawed testing/estimating methodology. Several commenters raised
serious concerns about the availability and implementation of accurate
test methods and emissions factors for condensable PM2.5.
They further stated that regulation of condensable PM2.5
emissions would be appropriate only after we have developed a workable
transitional strategy that ensures existing major sources are not
placed in ``NSR jeopardy'' for physical and operational changes
undertaken before new test methods and other requirements for
condensable PM2.5 are established.
In recognition of these concerns, both as they apply to the NSR
program and the broader air program, we have adopted a transition
period during which NSR permits need not address limits of condensable
PM2.5 emissions. During this transition period, EPA will
undertake a collaborative testing effort with industry, National
Association of Clean Air Agencies (NACAA), and other stakeholders to
assess and improve the effectiveness and accuracy of the available or
revised test methods. The purpose of the stakeholder testing projects
will be to collect new direct filterable and condensable
PM2.5 emissions data using methodologies that provide data
more representative of sources' direct PM2.5 emissions. The
EPA, States, and others will use these data to establish or improve
emissions factors and to define more representative source emissions
limits in permits.
The EPA acknowledges the legitimate concerns raised by commenters
concerning potential exposure to retroactive enforcement and has
established rules to address this issue. The EPA will not revisit
applicability determinations made in good faith prior to the end of the
transition period, insofar as the quantity of condensable PM emissions
are concerned, unless the applicable implementation plan clearly
required consideration of condensable PM. Likewise, EPA will interpret
PM emissions limitations in existing permits or permits issued during
the transition period as not requiring quantification of condensable
PM2.5 for compliance purposes unless such a requirement was
clearly specified in the permit conditions or the applicable
implementation plan.
After the end of the transition period (January 1, 2011 or any
earlier date established in the upcoming rulemaking codifying test
methods), EPA will require that all NSR applicability determinations
for PM2.5 and PM10 address condensable emissions
as applicable, and the source may not rely on calculations made for
previous determinations that did not include an accurate accounting of
condensables. Additionally, compliance with these limits must be
determined using the promulgated validated test methods that are
applicable after that date. Moreover, after that date, we expect that
condensable PM emissions will be addressed in all other aspects of the
major NSR program, such as impact analyses under PSD and offsets under
NA NSR. See 72 FR 20586, April 25, 2007 for the discussion of the
transition period as it applies to the other elements of the air
program in the final Clean Air Fine Particle Implementation Rule.
Although EPA is not requiring that State NSR programs address
condensable emissions of PM until the end of the transition period,
States that have developed the necessary tools are not precluded from
acting to measure and control condensable PM emissions in NSR permit
actions prior to the end of the transition period, especially if it is
required in an applicable SIP. To the extent that a State has the
supporting technical information and test methods, the State may assess
the capabilities of current control technologies, possible
modifications to such technologies, or new technologies as appropriate
relative to control of condensable PM2.5 emissions. As an
example, a specific approach for controlling condensable PM could be a
change in control device operating temperature to improve emissions
reductions. We also note that it is important that implementation of
any new or revised emissions limits and test methods that account for
condensable emissions should be prospective and clearly differentiated
from existing NSR permit requirements. This will avoid confusion over
the compliance status relative to existing PM emissions limits that
were not developed considering the condensable portion.
Notwithstanding the issues and uncertainties related to condensable
PM, we encourage States to begin immediately to identify measures for
reducing condensable PM emissions in major NSR permit actions,
particularly where those emissions are expected to represent a
significant portion of total PM emissions from a source.
F. Prevention of Significant Deterioration (PSD) Program Requirements
To receive a permit for a new major source or a major modification,
sources subject to PSD must:
Install Best Available Control Technology (BACT).
Conduct air quality modeling to ensure that the project's
emissions will not cause or contribute to either--
--A violation of any NAAQS or maximum allowable pollutant increase (PSD
increment); or
--An adverse impact on any Class I area ``air quality related value''
(AQRV).
As required, comply with preconstruction monitoring
requirements.
This final action regarding each of these elements is discussed in the
following sections.
[[Page 28336]]
1. How must BACT be implemented for PM2.5?
We are not making any change to our current regulations or policy
for implementing BACT requirements at a major source that is subject to
the requirements of the PSD program. Accordingly, if a new major source
will emit, or have the potential to emit, a significant amount of a
regulated NSR pollutant in an attainment area for that pollutant, the
source must apply BACT for each emissions unit that emits the
pollutant. In addition, if a physical or operational change at an
existing major source will result in a significant emissions increase
and a significant net emissions increase of a regulated NSR pollutant
in an attainment area for that pollutant, the source must apply BACT to
each proposed emissions unit experiencing a net increase in emissions
of that pollutant as a result of the physical or operational change in
the unit. Under the PM2.5 PSD program, these requirements
will apply to direct PM2.5 emissions; SO2
emissions; NOX emissions, unless a State demonstrates that
NOX is not a significant contributor to ambient
PM2.5 concentrations in that area; and to VOC if identified
by a State as a precursor in the PM2.5 attainment area where
the source is located.
2. How does EPA plan to address PM2.5 Increments,
Significant Impact Levels (SILs), and Significant Monitoring
Concentrations (SMCs)?
On November 1, 2005, we proposed a rule to implement the
PM2.5 NAAQS, including proposed revisions to the NSR program
(70 FR 65984). In that proposal, we indicated our intent to propose a
separate rule for developing PM2.5 increments, SILs, and
SMCs and sought comments on general approaches for developing these
values. We proposed PM2.5 increments, SILs, and SMCs in a
rule dated September 21, 2007. 72 FR 54112. We intend to address
comments received on these components of the PM2.5 PSD
program when we finalize that proposed rule.
3. What is the ambient air quality analysis requirement for
PM2.5?
All sources subject to PSD review must perform an ambient air
quality impact analysis to show that the emissions from the source will
not cause or contribute to a PSD increment or NAAQS violation. See
section 165(a)(3) of the CAA; 40 CFR 51.166(k) and 52.21(k). We did not
propose, and our final rules do not contain, any changes to the
regulations on air quality impact analyses for purposes of the
PM2.5 NSR program. Accordingly, sources will be required to
perform this analysis for the PM2.5 NAAQS and, when
finalized, PM2.5 increments. Such analyses must consider how
a source, in combination with other sources in the area, will impact
air quality at existing PM2.5 monitor locations, as well as
at other locations that are appropriate for comparing predicted
PM2.5 concentrations to the NAAQS based on PM2.5
monitor siting requirements and recommendations.
4. How must the PSD preconstruction monitoring requirement be
implemented for PM2.5?
Sources subject to PSD are subject to preconstruction ambient air
quality monitoring requirements. See sections 165(a)(7) and 165(e) of
the Act and 40 CFR 51.166(m) and 52.21(m). The PSD permitting
requirements provide that continuous preconstruction ambient air
quality monitoring must be conducted for any criteria pollutant emitted
in significant amounts. Under 40 CFR 51.166(i)(5) and 52.21(i)(5), the
reviewing authority has the discretion to exempt an applicant from this
monitoring requirement if:
The maximum modeled concentration for the applicable
averaging period caused by the proposed significant emissions increase
(or net emissions increase) is less than the prescribed SMC; or
The existing monitored ambient concentrations are less
than the prescribed SMC.
A source may also use existing data as a surrogate for preconstruction
monitoring if the existing monitored data record is determined to be
representative of the project's location.
We proposed five options for how to address preconstruction
monitoring for PM2.5. We are adopting a combination of
options 1 and 3 from the proposal, primarily because we believe that it
reflects existing procedures for other regulated NSR pollutants. The
following sections summarize the major comments received on each option
and explain why we are not adopting particular options.
Option 1--Require Preconstruction Monitoring for All Sources But Exempt
on a Case-by-Case Basis
Generally, commenters who supported option 1 believed the option
gives regulatory agencies enough flexibility to address sources with
unique characteristics. One commentator stated that another benefit is
that this option would avoid unnecessary installation of new
PM2.5 monitors and redundant preconstruction monitoring.
Another commenter, however, believed option 1 to be overly
burdensome until EPA develops an SMC. The commenter argued that for
example, there are many upcoming PSD projects in their State, which
would be located in extremely remote areas where there are no local or
regional PM2.5 emission sources, so there would be no need
to collect such data for these areas. Additionally, one group of
commenters stated that option 1 appeared to be ``streamlining''
preconstruction permit requirements, which is not the intention of the
Act's PSD provisions, and that EPA does not have the authority to
exempt sources from the requirements of section 165(e)(2).
We agree with the commenter that recommended combining option 3
(the use of a 24-hr PM2.5 SMC) with option 1 and are
finalizing this approach. We have proposed an SMC for PM2.5
in the rulemaking on increments, SILs, and SMCs (72 FR 54112, September
21, 2007). Our regulations at 40 CFR 51.166(i)(5) and 52.21(i)(5) have
allowed the use of an SMC as screening tool for identifying when an
impact is de minimis and there is thus little or no value in gathering
preconstruction monitoring data The use of de minimis levels of this
nature (such as significant emission rates and significant impact
levels) is supported by court precedent interpreting the NSR provisions
of the Act. Alabama Power Co. v. Costle, 636 F.2d 323, 360 (DC Cir.
1979). (``Unless Congress has been extraordinarily rigid, there is
likely a basis for an implication of de minimis authority to provide
[an] exemption when the burdens of regulation yield a gain of trivial
or no value.'')
Option 2--Exempt All Sources From Preconstruction Monitoring
Under option 2, we proposed to exempt all PM2.5 sources
from preconstruction monitoring through a blanket determination that
the existing PM2.5 monitoring network is sufficient. One
commenter who preferred option 5 (described subsequently) was also
supportive of option 2. This commenter noted that preconstruction
monitoring is expensive and can significantly delay a project. The
commenter also pointed out that it is very difficult to locate monitors
for both direct PM2.5 and precursors because precursors may
transport over long distances before transforming into
PM2.5. The commenter indicated that we should not rely on
the existing regulations, which are already known to be problematic.
One comment letter from a group of environmental advocacy
organizations specifically opposed option 2. These
[[Page 28337]]
commenters noted that spatial gradients can be significant for
PM2.5, especially for direct PM2.5 emissions, and
that the existing monitoring network is severely limited in its spatial
coverage, most especially in attainment areas where PSD preconstruction
monitoring requirements apply. The commenters indicated that to make a
blanket determination that the existing network suffices for any
source, regardless of where it might choose to locate, would be absurd.
We decided not to finalize option 2 because we do not believe that
the current network will be sufficient for all existing and potential
new sources. As stated in the proposal preamble, we believe that the
existing PM2.5 monitoring record has the following
limitations:
The PM2.5 monitoring data record would require
spatial interpolation between monitors for the determination of
appropriate concentrations at the project's location.
Use of existing monitored data will not increase the
PM2.5 monitoring data record to confirm or contradict
conventional perceptions.
The PM2.5 monitoring data record assumes that
local hot spots of high PM2.5 concentrations do not exist or
are already being monitored, which may not be true in all cases.
Automatic acceptance of existing measurements does not
follow our current policy that a case-by-case determination needs to be
made to determine whether preconstruction ambient monitoring is
necessary.
When used with the impact modeling, separate
concentrations of direct and precursor-formed PM are needed.
Option 3--Use SMC's To Exempt Sources From Preconstruction Monitoring
Several commenters supported this option adding that this approach
follows existing procedures to justify the exclusion of preconstruction
monitoring requirements when source impacts are less than the SMC or
when sufficient representative data exists. One group of commenters
stated that EPA's proposed options 1 and 3, which would allow case-by-
case or de minimis exemptions from the monitoring requirements, are
ill-conceived as a matter of public policy and contradict the Act's PSD
provisions.
We agree with the commenters that support adopting option 3 because
a combination of options 1 and 3 reflects existing procedures for other
regulated NSR pollutants. As discussed previously, a de minimis
exemption from monitoring requirements is supported by court precedent
interpreting the PSD provisions of the Act. We do not consider it sound
policy to require gathering additional data when it is unnecessary to
demonstrate that a proposed source or modification will not adversely
impact air quality.
Option 4--Use Existing PM10 Data
We proposed using the available large PM10 data record
combined with the recently acquired PM2.5 data to provide
representative ambient measurements for most sources. One comment
letter from an industry group opposed any requirement for
preconstruction monitoring, and endorsed option 4 if nationally
gathered PM2.5 data is not available. Three commenters
specifically opposed option 4. One comment letter from an environmental
advocacy organization stated that option 4 is illegal on its face, to
the extent that EPA intends it as a universally available alternative.
This comment indicated that some individual sources might be able to
demonstrate that PM10 monitoring could fulfill the statutory
requirements and purposes of PM2.5 monitoring (e.g., with
sufficiently protective assumptions about PM2.5/
PM10 proportions), but due to the variability in the
relationship between PM2.5 and PM10, EPA cannot
categorically allow this substitution. Two other commenters stated that
option 4 was not a viable approach due to the convoluted nature of
attempting to infer PM2.5 concentration from PM10
monitoring data for source-specific applications.
We decided not to finalize option 4. As we recognized in the
proposal preamble, the differences in characteristics between
PM2.5 and PM10 and our limited understanding of
their relationship are problematic for this application. We do not
believe that generalized factors to convert PM10
concentrations to PM2.5 concentrations sufficiently reflect
important industry-specific and spatially-related characteristics of
PM2.5. In addition, removing altogether the obligation to
provide preconstruction PM2.5 ambient monitoring data would
eliminate industry's contribution to the PM2.5 data record
when source impacts are more than de minimis.
Option 5--Exempt Sources From Preconstruction Monitoring if No SMC Is
Established
We noted in the proposed rule that the existing regulations at 40
CFR 51.166(i)(5)(iii) and 52.21(i)(5)(ii) could be interpreted to allow
a reviewing authority to exempt an applicant from preconstruction
monitoring for any pollutant for which we have not established an SMC.
These provisions state that a source may be exempted from
preconstruction monitoring ``if * * * the pollutant is not listed in''
the list of pollutants for which SMC have been set.\13\ The original
rationale for this exemption is based on the lack of adequate methods
for measuring ambient concentrations of pollutants not on the list. See
45 FR 52709, 52723-52724. We requested comment on this interpretation
and any other legal or policy rationale that could support applying the
text of these provisions to exempt sources from preconstruction
monitoring if we elected not to define an SMC for PM2.5.
---------------------------------------------------------------------------
\13\ These sections actually cross-reference the list at 40 CFR
51.166(i)(8)(i) and 52.21(i)(8)(i), however we renumbered those
paragraphs to paragraph (i)(5)(i) of those provisions in the
December 31, 2002 NSR reform rule and inadvertently overlooked
correcting the cross-references in paragraphs (i)(5)(ii) and
(i)(5)(iii). See 67 FR 80186. As proposed, in this final action we
have corrected this misnumbering and others in this section.
---------------------------------------------------------------------------
One commenter stated that option 5 is the most practicable to
implement until an SMC can be established and any potential gaps in the
monitoring network can be filled. Two commenters question the legality
of option 5 under the Act. They added that whatever may have been the
case when the existing list of SMCs was adopted, methods now exist for
conducting the monitoring required under section 165(e)(2). We decided
not to finalize option 5, and have proposed an SMC rule for
PM2.5.
In conclusion, we are finalizing a combination of options 1 and 3
from the proposal, since we believe that it reflects existing
procedures for other regulated NSR pollutants. Once we finalize an SMC
for PM2.5, the reviewing authority will have the discretion
to exempt a source from the preconstruction monitoring requirement if
the projected PM2.5 ambient impact of the source is below
the PM2.5 level promulgated in our rules. In addition,
additional preconstruction monitoring data may not be necessary based
on the availability of existing representative monitoring data in the
area, as discussed previously.
G. Nonattainment New Source Review (NA NSR) Requirements
To receive a permit for a new major source or a major modification,
sources subject to NA NSR must:
Install Lowest Achievable Emission Rate (LAER) control
technology;
Offset new emissions with creditable emissions reductions;
[[Page 28338]]
Certify that all major sources owned or operated by the
applicant in the same State are in compliance; and
Conduct an alternative siting analysis demonstrating that
the benefits of the proposed source significantly outweigh the
environmental and social costs.
We did not propose, nor are we finalizing, any revisions to the first,
third, and fourth of these requirements. Thus, these requirements apply
for purposes of PM2.5 and its designated precursors just as
they apply for other criteria pollutants and their designated
precursors. In the remainder of this section G, we discuss our final
actions related to offsets for direct PM2.5 emissions and
emissions of PM2.5 precursors.
1. What is the required offset ratio for direct PM2.5
emissions?
Under section 173 of the Act, all major sources and major
modifications at existing major sources within a nonattainment area
must obtain emissions reductions to offset any emissions increases
resulting from the project in an amount that is at least equal to the
emissions increase, and that is consistent with reasonable further
progress towards attainment. We refer to the proportional difference
between the amount of the required offsets to the amount of emissions
increase as the ``offset ratio.''
The Act specifies an offset ratio for several situations. In ozone
nonattainment areas subject to subpart 2 (of title I, part D of the
Act), the ratio is set between 1.1:1 and 1.5:1 depending on the area's
level of classification pursuant to subpart 2. For other nonattainment
areas, the Act establishes a minimum offset ratio of 1:1 pursuant to
subpart 1 of title I, part D of the Act.
As proposed, we are finalizing the offset ratio for direct
PM2.5 emissions as at least 1:1 on a mass basis because the
PM2.5 program is being implemented under subpart 1 of the
Act. The commenters on this issue generally agreed that our regulations
should require an offset ratio of at least 1:1 pursuant to subpart 1.
A few commenters indicated that a lower ratio could be acceptable
on a source-specific basis if accompanied by a modeling analysis
demonstrating a net air quality benefit. One commenter suggested that
such a demonstration would be possible when a direct PM2.5
emissions increase from a tall stack is being offset by ground-level
PM2.5 emission reductions. Applying diesel retrofit
technology to bus and truck fleets is an example of how ground-level
PM2.5 emission reductions could be achieved. We do not
believe that a lower offset ratio is authorized under subpart 1, which
prescribes an offset ratio of at least 1:1, and therefore we have not
adopted this approach in our final rules.
Some of the commenters disagreed regarding whether an offset ratio
of at least 1:1 under subpart 1 represents a ceiling or a floor on the
level we can prescribe in our regulations. We interpret section 173 of
the Act to allow higher offset ratios where necessary to achieve
reasonable further progress. Accordingly, we believe that States may
establish higher offset ratios in their State programs if they wish,
but we do not believe that it would be appropriate for us to do so for
PM2.5 in national regulations. We do not have cause to
believe a higher ratio is necessary for PM2.5 in each area
of the country and prefer to leave this to the discretion of States. We
do not believe that the higher offset ratios required for ozone
precursors under subpart 2 apply in any way to direct PM2.5
emissions or PM2.5 precursors.
2. Which precursors are subject to the offset requirement?
Consistent with our proposal, the pollutants that are designated as
PM2.5 precursors in a particular area are subject to the
offset requirement in that area. Accordingly, SO2 is subject
to offsets in all PM2.5 nonattainment areas. As a
``presumed-in'' precursor, NOX will be subject to offsets
unless a State obtains an exemption for its NSR program through a
demonstration that NOX emissions in a particular area are
not a significant contributor to that area's ambient PM2.5
concentrations. As ``presumed-out'' precursors, VOC and ammonia would
be subject to offsets only in areas where the State has demonstrated
that these emissions are significant contributors to the area's ambient
PM2.5 concentrations. Two commenters on this issue agreed
with this approach; one commenter recommended that we not require
offsets for any PM2.5 precursors. We believe that it is
appropriate to offset emissions increases of all precursors that have
been established to contribute to the PM2.5 nonattainment
problem in a particular area.
3. What is the required offset ratio for PM2.5 precursors?
As discussed previously, the Act requires that a source obtain
offsets for emissions increases that occur in a nonattainment area. As
with PM2.5 direct emissions, the minimum offset ratio
permitted under subpart 1 of the Act is at least 1:1. Based on these
requirements of the Act, we are finalizing our proposal that an offset
ratio of at least 1:1 applies where a source seeks to offset an
increase in emissions of a PM2.5 precursor with creditable
reductions of the same precursor. This offset ratio applies for all
pollutants that have been designated as PM2.5 precursors in
a particular nonattainment area.
Most commenters agreed with this approach. A few commenters
indicated that an offset ratio of less than 1:1 for precursor emissions
of PM2.5 should be allowed only if there is a net air
quality benefit and if the lower ratio is justified by air quality
modeling analysis. They noted that for PM2.5 precursors,
chemical reactivity modeling demonstrations should be developed and
approved that are, at a minimum, capable of determining the impacts of
the precursor emissions on the air quality in the nonattainment area in
which the source is located. As noted previously, we do not believe
that any offset ratio less than 1:1 is permissible under subpart 1.
One commenter stated that consistent with the statutory scheme for
ozone laid out in section 182, and given the severity of the health
risks associated with PM2.5, EPA must require offsets of at
least 1.15:1 for PM2.5 precursors in ``moderate''
nonattainment areas, and must increase the offset ratio in ``serious''
nonattainment areas or in areas that request extensions of their
attainment deadlines. As mentioned previously, we do not believe that
subpart 2 of the Act (which includes section 182) has any relevance to
PM2.5 or its precursors. Subpart 2 is specific to ozone. In
addition, we are implementing the PM2.5 program under
subpart 1. Nevertheless, under the Act, we believe that a State may
require higher offset ratios if it determines that they are necessary
to achieve reasonable further progress. For the reasons discussed
previously with respect to direct PM2.5, we do not believe
that it is appropriate for us to set higher offset ratios for
PM2.5 precursors on a national basis.
Two commenters requested that we make clear in the final rule that
an increase in precursor emissions need only be offset once, even if
the increase triggers nonattainment NSR under, for example, both the
ozone and PM2.5 programs. We agree with these commenters and
are clarifying that a precursor emissions increase only needs to be
offset once. A permit applicant will not, for example, need to obtain
two sets of offsets for NOX emissions if NOX is
regulated as a precursor both for ozone and PM2.5 in the
area. The NOX precursor emissions need only be offset once
in accordance with the applicable
[[Page 28339]]
ratio. To the extent a higher ratio applies for ozone under subpart 2,
the applicant would have to obtain offsets at the higher ratio.
However, when the offset ratios are the same, both requirements can be
met with a single set of NOX offsets.
4. Is interpollutant trading allowable to comply with offset
requirements?
In this final rule, we are allowing limited interpollutant trading
for purposes of offsets only (and not netting) under the
PM2.5 NA NSR program. Specifically, the final rules allow
interpollutant trading only based on a trading ratio established in the
SIP as part of the attainment demonstration approved for a specific
nonattainment area, on a statewide basis, or in a regional, multi-state
program. This differs from our proposal in that the final rules do not
allow interpollutant trading on a case-by-case basis as part of an
individual NA NSR permitting process. For the purpose of offsets in the
NA NSR program for PM2.5, the final rules allow reductions
in direct PM2.5 emissions to offset precursor emissions
increases, emissions reductions of one precursor to offset emissions
increases of another precursor, and reductions in precursor emissions
to offset direct PM2.5 emissions increases.
We have completed a technical assessment to develop preferred
interpollutant trading ratios that may be used for the purposes of
PM2.5 offsets, where appropriate. The preferred ratios were
generated with a PM2.5 response surface modeling (RSM)
approach based on the EPA's Community Multi-Scale Air Quality (CMAQ)
model. This RSM approach allows one to distinguish the impact of direct
and precursor emissions from particular source groupings on total
PM2.5 concentrations within nine specific urban areas and
broadly across U.S. regions. This approach was recently applied by the
Agency to inform development of potential PM2.5 control
strategies as part of the Regulatory Impact Assessment (RIA) for the
final PM2.5 NAAQS.\14\ Based on results from the RSM, we
determined the distribution of predicted ratios for urban areas and
regions across the country and developed the preferred ratios with a
goal to be environmentally protective. The technical approach with
details on data and modeling inputs are fully described in a technical
memo to the docket, ``Details on Technical Assessment to Develop
Interpollutant Trading Ratios for PM2.5 Offsets.'' \15\ Use
of the preferred ratios is recommended by EPA but not mandatory, and we
do not intend to preclude the opportunity for a local demonstration of
trading ratios on a case-by-case basis and public input into that
process.
---------------------------------------------------------------------------
\14\ A full description of this approach is available in the
technical support document at http://www.epa.gov/scram001/reports/pmnaaqs_tsd_rsm_all_021606.pdf and in the docket for this
rulemaking, Docket ID No. EPA-HQ-OAR-2003-0062.
\15\ Available in the docket for this rulemaking, Docket ID No.
EPA-HQ-OAR-2003-0062.
---------------------------------------------------------------------------
Our work here and in other recent PM2.5 assessments
clearly show that the relative efficacy of emissions reductions varies
across pollutants and that a ton of direct PM2.5 is
generally more effective than a ton of precursor emissions in reducing
overall PM2.5 concentrations. For the purposes of reporting
information here, we define the ``East'' to be the 37 States either
completely or in part east of 100 degrees west longitude. ``West''
would include the remaining 11 western-most States in the continental
United States. We found the following relationships between pollutants
in developing the preferred trading ratios:
1. NOX to SO2; SO2 to
NOX: Our assessment indicated potential disbenefits of
reducing NOX (i.e., reducing NOX tons in urban
areas may increase overall PM2.5 concentrations) in the
eastern United States and urban areas in the western United States.
Due to the possibility of these disbenefits and the high degree of
variability in the observed NOX to SO2 ratios
or SO2 to NOX ratios across urban areas, we
are not defining preferred ratios involving trades between these
precursors but will rely upon a local demonstration to determine the
appropriate trading ratios.
2. NOX to Primary PM2.5; Primary
PM2.5 to NOX: Based on a local demonstration
that NOX reductions are beneficial in reducing
PM2.5 concentrations (i.e., no disbenefits from
NOX reductions as noted previously), our assessment
indicates that the preferred trading ratio is 200 to 1
(NOX tons for PM2.5 tons) or 1 to 200
(PM2.5 tons for NOX tons) for areas in the
eastern United States, and 100 to 1 (NOX tons for
PM2.5 tons) or 1 to 100 (PM2.5 tons for
NOX tons ) for areas in the western United States.
3. SO2 to Primary PM2.5; Primary
PM2.5 to SO2: We have determined a nationwide
preferred ratio of 40 to 1 (SO2 tons for PM2.5
tons) or 1 to 40 (PM2.5 tons for SO2) for
trades between these pollutants. We recognize there is spatial
variability here between urban and regionally located sources of
these pollutants that can be addressed through a local demonstration
to determine an area-specific relationship, as appropriate.
We recommend that States use these hierarchies and trading ratios
in their interpollutant trading programs to provide consistency and
streamline the trading process. As indicated by our work and findings,
it is appropriate to establish acceptable trading ratios for
interpollutant trading for PM2.5 NSR offsets. If States
elect to use EPA's recommended trading ratios, they may rely on EPA's
technical work and a presumption that such ratios will be approvable by
EPA absent a credible showing that EPA's trading ratios are not
appropriate for that location. If States choose to develop their own
hierarchies/trading ratios, they will have to substantiate by modeling
and/or other technical demonstrations of the net air quality benefit
for PM2.5 ambient concentrations, and such a trading program
will have to be approved by EPA.
We acknowledge that the relationship between pollutants can vary
across geographic areas. Thus, local demonstrations, to determine
trading ratios, will need to address a number of local factors
including, but not limited to, the following:
1. The relative magnitude of emissions of direct
PM2.5 and precursor gases (e.g., SO2 and
NOX) within the geographic area of interest.
2. The relative contribution to local PM2.5
nonattainment of directly emitted PM2.5 and individual
precursors from the various sources or source categories under
consideration as part of a potential interpollutant trade.
3. The meteorological conditions and topography of the area,
which result in different source-receptor relationships across
pollutants within the local area.
We have adopted this approach to capture the flexibility advantages
of interpollutant trading, while remaining mindful of the limitations
of existing air quality models. We believe that the regional-scale
models used for area-wide attainment demonstrations have sufficient
accuracy to establish an overall equivalence ratio for a nonattainment
area. However, we do not believe that available models can accurately
determine the effects of interpollutant trades at a single source. In
addition, permit-by-permit modeling demonstrations are extremely
resource intensive, only to yield limited results. For these reasons,
the final rules only allow a State to develop its own interpollutant
trading rule for inclusion in its SIP, based on a technical
demonstration for a specific nonattainment area. We will not accept
case-by-case demonstrations on an individual source permit basis.
The flexibility provided by this policy allows sources to select
the most cost-effective manner to obtain the offsets necessary to
ensure that PM2.5 air quality improves. This will be
particularly beneficial where offsets for one particular pollutant are
scarce in a particular area, as is often the case for direct
PM2.5 emissions and SO2.
[[Page 28340]]
We received a large number of comments on this issue representing a
wide variety of viewpoints. Several commenters supported flexible
interpollutant trading at ratios established either on an area-wide
basis or permit by permit. They often pointed out the economic and
administrative benefits of flexibility in the program, especially in
areas where offsets for some pollutants will be difficult to obtain.
One commenter asserted that such flexibility is essential to the
ability of enterprises to be able to expand as the PM2.5
NAAQS is implemented, especially in the program's early years. Another
commenter suggested allowing such trading on an equal basis, without
the ``unnecessary complication'' of interpollutant offset ratios.
Many commenters argued against allowing interpollutant trading for
offsets. These commenters commonly pointed out that direct
PM2.5 emissions typically have a more local impact, while
the impact of precursor emissions are farther afield. A number of
commenters pointed out the complex atmospheric chemistry of secondary
particulate formation and the shortcomings of the air quality models
currently available to perform a detailed PM2.5 formation
assessment, specifically that local-scale models are not sufficiently
accurate and regional-scale models do not have the resolution to show
local impacts adequately. According to two commenters, trading
precursors for direct PM2.5 emissions raises serious
environmental justice concerns due to the localized impacts of direct
PM2.5 emissions. These commenters also asserted that the
equivalence between precursors would vary spatially and temporally,
making it extremely difficult to assess, and that PM2.5
precursors also differ in their impacts on other air pollution
problems, such as direct health and welfare impacts of SO2
and NOX; and formation of ozone, acid deposition, and
reactive nitrogen deposition.
We also received comments opposing allowing interpollutant trading
for netting purposes, on the basis that the resulting program would be
very staff-intensive apart from the difficulty of demonstrating through
modeling the net air quality benefit of a single source trade. We
concur with these commenters and are not allowing interpollutant
trading for netting purposes at this time.
A number of commenters supported some types of trades, but not
others. Most frequently, these commenters favored allowing reductions
in direct PM2.5 emissions to offset precursor emissions
increases. One commenter suggested a hierarchy as follows: Direct
PM2.5 emissions, SO2, NOX, ammonia,
and VOC. That is, a pollutant should be allowed as an offset for a
pollutant ranked lower, but not the reverse (e.g., reductions in direct
PM2.5 emissions could be used to offset increases in any of
the listed pollutants, SO2 emissions reductions could offset
NOX increases, etc.).
As previously noted, this rule allows interpollutant and
interprecursor trading of offsets according to a SIP-approved trading
program. To be approved, the trading program must either adopt EPA's
recommended trading ratios or be backed up by regional-scale modeling
that demonstrates a net air quality benefit using appropriate overall
offset ratios for such trades for a specified nonattainment area,
State, or multi-State region. There is considerable uncertainty about
the relationship of precursor and direct PM2.5 emissions to
localized ambient PM2.5 concentration both spatially and
temporally. Given the uncertainty as to localized adverse and
beneficial effects, we have opted for program flexibility. We believe
this is necessary, in part, because of the shortage of available
offsets for some pollutants, particularly direct PM2.5
emissions and SO2, in many areas.
H. How will the transition to the PM2.5 PSD requirements
occur?
1. Background
On October 23, 1997, after the NAAQS for PM2.5 was
originally promulgated, we issued a guidance document entitled
``Interim Implementation for the New Source Review Requirements for
PM2.5,'' John S. Seitz, EPA. As noted in that guidance,
section 165 of the Act suggests that PSD requirements become effective
for a new NAAQS upon the effective date of the NAAQS. Section 165(a)(1)
of the Act provides that no new or modified major source may be
constructed without a PSD permit that meets all of the section 165(a)
requirements with respect to the regulated pollutant. Moreover, section
165(a)(3) provides that the emissions from any such source may not
cause or contribute to a violation of any NAAQS. Also, section
165(a)(4) requires BACT for each pollutant subject to PSD regulation.
The 1997 guidance stated that sources should continue to use
implementation of a PM10 program as a surrogate for meeting
PM2.5 NSR requirements until certain difficulties were
resolved, primarily the lack of necessary tools to calculate the
emissions of PM2.5 and related precursors, the lack of
adequate modeling techniques to project ambient impacts, and the lack
of PM2.5 monitoring sites. With this final action and
technical developments in the interim, these difficulties have largely
been resolved.
2. Transition for ``Delegated States''
The Federal PSD program is contained in 40 CFR 52.21. This section
is the Federal implementation plan for areas lacking an approved PSD
program. We implement this program in Indian country and some U.S.
territories, but for the most part we have delegated implementation of
40 CFR 52.21 to those States without approved PSD programs (typically
referred to as ``delegated States''). Except as provided in the
grandfathering provisions that follow, these final rules go into effect
and must be implemented beginning on the effective date of this rule,
July 15, 2008 in all areas subject to 40 CFR 52.21, including the
delegated States.
Consistent with 40 CFR 52.21(i)(1)(x), wherein EPA grandfathered
sources or modifications with pending permit applications based on PM
from the PM10 requirements established in 1987, EPA will
allow sources or modifications who previously submitted applications in
accordance with the PM10 surrogate policy to remain subject
to that policy for purposes of permitting if EPA or its delegate
reviewing authority subsequently determines the application was
complete as submitted. This is contingent upon the completed permit
application being consistent with the requirements pursuant to the EPA
memorandum entitled ``Interim Implementation of New Source Review
Requirements for PM2.5'' (Oct. 23, 1997) recommending the
use of PM10 as a surrogate for PM2.5.
Accordingly, we have added 40 CFR 52.21(i)(1)(xi) to reflect this
grandfathering provision.
3. Transition for ``SIP-Approved States''
The requirements for State PSD programs are contained in 40 CFR
51.166. Most States have developed PSD programs according to these
requirements, which we have approved into each State's implementation
plan. States with PSD programs approved under 40 CFR 51.166 are called
``SIP-approved States.''
States with SIP-approved PSD programs that require amendments to
incorporate these final NSR rule changes for PM2.5 will need
time to accomplish these SIP amendments. For example, a State may need
to amend its existing regulations to add the specific significant
emissions rate for PM2.5 or a designated precursor. In our
December 31, 2002 Federal Register notice
[[Page 28341]]
promulgating other changes to the NSR program, we explained that the
Act does not specifically address the timeframe by which States must
submit SIP revisions when we revise the PSD and NA NSR rules. We
nonetheless looked to section 110(a)(1) to guide our decision to
require States to adopt and submit plan revisions within 3 years from
when we publish changes in the Federal Register. We codified this
approach in the PSD regulations at 40 CFR 51.166(a)(6)(i) and applied
this same timeframe to State NA NSR programs through that final rule
action. 64 FR 80241. This rule follows our established approach for
determining when States must adopt and submit revised SIPs following
changes to the NSR regulations, but does not revise otherwise
applicable SIP submittal deadlines. Accordingly, we are requiring
States with SIP-approved PSD programs to submit revised PSD programs
and revised NA NSR programs for PM2.5 (see section V.I.)
within 3 years from the date of this action.\16\
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\16\ In our proposal, we proposed April 5, 2008 as a deadline
for States to comply with the revised nonattainment NSR and PSD
requirements in this rule. However, in light of the time it has
taken to complete this final rule, expecting States to submit
required SIP revisions consistent with this final rule by April 5,
2008 is no longer practical or fair. Nevertheless, States are still
currently required to implement a PSD program for PM2.5,
and we still expect States to fulfill the SIP infrastructure
requirements of CAA section 110(a)(2), including the PSD program
requirements, by April 5, 2008. We believe these PSD program
requirements are currently met by implementing the transitional PSD
program for PM2.5 described in this preamble (a.k.a. the
PM10 surrogate policy). In accordance with a Consent
Decree in Environmental Defense and American Lung Ass'n v. Johnson,
No. 1:05CV00493 (D.D.C. June 15, 2005), EPA must determine by
October 5, 2008 whether each State has submitted the SIP revisions
for the PM2.5 PSD program required under section
110(a)(2) of the Act. This rulemaking does not change the specific
guidance we previously provided to States on what they should submit
by April 5, 2008 to comply with section 110(a)(2).
---------------------------------------------------------------------------
During this SIP development period, the PM2.5 NAAQS must
still be protected under the PSD program in such States. We are
finalizing our proposed option 1 that if a SIP-approved State is unable
to implement a PSD program for the PM2.5 NAAQS based on
these final rules, the State may continue to implement a
PM10 program as a surrogate to meet the PSD program
requirements for PM2.5 pursuant to the 1997 guidance
mentioned previously. Under option 1 for SIP-approved States, we had
proposed two additional requirements. These were to require sources to
demonstrate that emissions from construction or operation of the
facility will not cause or contribute to a violation of the
PM2.5 NAAQS and to include condensable PM emissions in
determining major NSR applicability and control requirements. We are
not finalizing either of these additional requirements of our proposed
option 1. We have dropped the requirement for demonstrating compliance
with the PM2.5 NAAQS in order to maintain consistency in the
application of the existing surrogate policy across the PSD program
during the interim period. Since in the final rule we are otherwise
allowing SIP-approved States to continue with the existing
PM10 surrogate policy to meet the PSD requirements for
PM2.5, partially implementing the PM10 surrogate
policy in this manner would be confusing and difficult to administer.
Thus, to ensure consistent administration during the transition period,
we have elected to maintain our existing PM10 surrogate
policy which only recommends as an interim measure that sources and
reviewing authorities conduct the modeling necessary to show that
PM10 emissions will not cause a violation of the
PM10 NAAQS as a surrogate for demonstrating compliance with
the PM2.5 NAAQS. Also as discussed previously in section
V.E, we are not requiring condensable emissions to be fully integrated
into the PM2.5 program until the end of the transition
period to validate test methods discussed in section V.E of this
preamble.
In our proposal, we offered two additional options for the SIP
development period in States with SIP-approved PSD programs. Under
option 2, we would have updated the 1997 guidance to reflect the
provisions in these final rules and allowed States to run a
PM2.5 program pursuant to this updated guidance.
Alternatively under option 2, we would have amended appendix S and 40
CFR 52.24 so that the PSD requirements of 40 CFR 52.21 would govern the
issuance of major NSR permits during the SIP development period.
Finally, under option 3, we would have allowed a State to request
delegation of just the Federal PM2.5 PSD program in 40 CFR
52.21 in that State. A State that otherwise had a SIP-approved PSD
program could have requested delegation for PM2.5 by
informing us that it did not intend to submit a PSD SIP for
PM2.5 in the immediate future.
We received several comments supporting option 1, although some of
these commenters requested that we not require condensable emissions to
be included until the concerns with test methods were resolved. One of
these commenters favored continuing to implement the PM10
program as a surrogate under the 1997 guidance to provide clarity and
certainty to the permitting agency and regulated community. The
commenter indicated that PM2.5 inventories and methods for
estimating emission rates are rudimentary and may even be nonexistent
in some cases, which would make permitting onerous.
A few commenters opposed option 1. One of these commenters
indicated that we should not continue outdated policy (i.e., the 1997
NSR guidance) because it does not address the PM2.5 problem,
cannot be implemented in some States, and does not incorporate
precursor emissions.
Four commenters expressed support for option 2. Three of these
suggested that we issue updated guidance to incorporate these PSD
requirements for PM2.5, while one preferred that we revise
appendix S to point to the requirements of 40 CFR 52.21. We received
one comment in favor of option 3 and three opposed.
Two commenters supported approaches different from our options. One
of these commenters requested that the interim framework should, at a
minimum, ensure that any new or modified project that exceeds
thresholds use BACT. The commenter also suggested that we require
offsets for projects approved before the other protective elements of
the full PSD program are in place to ensure that there is no
significant deterioration in air quality. Another commenter stated that
none of the proposed options were viable for their State. The commenter
requested that we allow States to continue their existing PM10 program
as a surrogate for PM2.5, without caveat.
As noted previously, we are finalizing proposed option 1, without
the requirement of demonstrating compliance with the PM2.5 NAAQS or the
requirement to include condensable emissions. We believe that our final
rule is reasonable for the following reasons. First, PM10 will act as
an adequate surrogate for PM2.5 in most respects, because all new major
sources and major modifications that would trigger PSD requirements for
PM2.5 would also trigger PM10 requirements because PM2.5 is a subset of
PM10. Second, both of the precursors designated in the final rule--SO2
and NOX (presumptively)--are already regulated under State NSR programs
for other criteria pollutants. Thus, those precursors will be subject
to NSR through those other programs. We do not believe that the other
options or suggestions offer significant advantages that outweigh the
utility and ease of implementation of this approach.
States may include grandfathering provisions similar to the ones
EPA
[[Page 28342]]
included in the transition requirements for 40 CFR 52.21.
I. How will the transition to the PM2.5 NA NSR requirements occur?
1. Background
The requirements for State NA NSR programs are contained in 40 CFR
51.165. All States with nonattainment areas have developed NA NSR
programs according to these requirements, which we have approved into
each State's implementation plan. However, as noted previously, it
takes time for a State to amend its SIP when it must make changes to
its NA NSR program. According to the provisions of 40 CFR 52.24(k),
during such an interim period when a State lacks an approved NA NSR
program for a particular pollutant, appendix S of 40 CFR part 51
applies for NA NSR permitting.
Section 172(c)(5) of the Act requires that States issue major NSR
permits for construction and major modifications of major stationary
sources in any nonattainment area. Thus, since the PM2.5 nonattainment
designations became effective on April 5, 2005, States are now required
to issue major NSR permits that address the section 173 NA NSR
requirements for PM2.5.
On the date that the PM2.5 nonattainment designations took effect
(April 5, 2005), we issued guidance to address implementation of the NA
NSR program pending the completion of this action to develop
implementation rules for PM2.5. See memorandum from Stephen D. Page,
Director, Office of Air Quality Planning and Standards to Regional Air
Directors, ``Implementation of New Source Review Requirements in PM2.5
Nonattainment Areas'' (April 5, 2005).
Our current guidance permits States to implement a PM10 NA NSR
program as a surrogate to address the requirements of NA NSR for the
PM2.5 NAAQS. A State's surrogate major NSR program in PM2.5
nonattainment areas may consist of either the implementation of the
State's SIP-approved NA NSR program for PM10 or implementation of a
major NSR program for PM10 under the authority in 40 CFR part 51,
appendix S.
2. Transition
With this finalization of the new PM2.5 NSR implementation
requirements under 40 CFR 51.165, States now have the necessary tools
to implement a NA NSR program for PM2.5. After the effective date of
the amended rule (that is, July 15, 2008, States will no longer be
permitted to implement a NA NSR program for PM10 as a surrogate for the
PM2.5 NA NSR requirements. Most States will then need to implement a
transitional PM2.5 NA NSR program under appendix S (as amended in this
rulemaking action) until EPA approves changes to a State's SIP-approved
NA NSR program to reflect the new requirements under 40 CFR 51.165. At
this time, we do not believe it is appropriate to allow grandfathering
of pending permits being reviewed under the PM10 surrogate program in
nonattainment areas, mainly because of a State's obligations to
expedite attainment and the fact that we had not established a similar
precedent for transitioning from PM to PM10.
The NA NSR provisions in a State's existing SIP-approved NA NSR
program would also apply in areas designated as nonattainment for the
PM2.5 NAAQS if the SIP-approved regulations contain a generic
requirement to issue part D permits in areas designated as
nonattainment for any criteria pollutant and do not otherwise need to
be amended to incorporate the changes finalized in this action. States
belonging to the following categories will need to revise their NA NSR
regulations and submit them to EPA for incorporation into the SIP
within 3 years from the date of this action \17\:
---------------------------------------------------------------------------
\17\ As discussed earlier, we are following the precedent we
established in our 2002 rule for NA NSR program revisions to allow
States adequate time to adopt these revisions. For practical and
fairness reasons, we are not requiring the NA NSR elements of this
rule to be submitted by April 5, 2008, as we had proposed. However,
the States are still required to submit nonattainment plans for
PM2.5 (including NA NSR programs) on April 5, 2008. We believe this
requirement is satisfied by implementing the transitional NA NSR
program for PM2.5 (a.k.a. the PM10 surrogate policy) described in
our April 5, 2005 guidance, or, if submitted after the effective
date of this rule, implementing Appendix S as revised in this rule.
This rulemaking does not change the specific guidance we previously
provided to States on what they should submit to EPA by April 5,
2008 to comply with nonattainment area requirements under Part D.
---------------------------------------------------------------------------
States that have nonattainment regulations which need to
be amended to incorporate the new PM2.5 requirements.
States that have designated nonattainment areas for PM2.5
and their nonattainment NSR regulations specifically list the areas in
which NA NSR applies (i.e., the list does not include the designated
nonattainment areas for PM2.5).
States that have not previously had nonattainment areas
but now have nonattainment areas for PM2.5.
These States will have to implement a transitional NA NSR
permitting program for PM2.5 pursuant to 40 CFR 52.24(k) and appendix S
until their existing part D SIPs are revised to meet these new PM2.5
NSR requirements under 40 CFR 51.165.
3. Implementation of NSR Under the ``Emissions Offset Interpretative
Ruling'' (40 CFR Part 51, Appendix S) With Revisions
In general, appendix S requires new or modified major sources to
meet LAER and obtain sufficient offsetting emissions reductions to
assure that a new major source or major modification of an existing
major source will not interfere with the area's progress toward
attainment. Readers should refer to appendix S for a complete
understanding of these and other appendix S requirements. In this
action, we are finalizing our proposed revisions to appendix S to
include provisions necessary to implement a transitional NA NSR program
for PM2.5, including significant emissions rates applicable to major
modifications for PM2.5 and, as appropriate, precursors. Additionally,
since we are finalizing interpollutant trading provisions in the NSR
rules at 40 CFR 51.165, we are also amending appendix S to allow
interpollutant trading for PM2.5. Appendix S applies directly to new
and modified major stationary sources. In accordance with the
requirements of section 110(a)(2)(c) of the Act, we believe that the
majority of States have the legal authority to issue permits consistent
with these requirements under an existing SIP-approved permitting
program. Nonetheless, at least one State has reported that it lacks the
legal authority to issue permits implementing the requirements of
appendix S under its existing permitting rules.
If a State is unable to apply the requirements of appendix S, we
will act as the reviewing authority for the relevant portion of the
permit. We believe that it is appropriate for EPA to issue the
preconstruction permits in such circumstances. Congress amended the Act
in 1990 to remove the requirements that would have applied a
construction ban in areas that lacked a SIP-approved part D permit
program. Thus, we believe that it is consistent with Congressional
intent that either the State or EPA issues construction permits for
those projects meeting the applicable criteria during the interim
period. See the preamble of the proposal for this rule for more detail
on the legal basis for requiring States to issue NA NSR permits
pursuant to appendix S during the SIP development period (70 FR 66045-
46).
We received three comments supporting the issuance of NA NSR
permits under appendix S during the SIP development period. Two of
these
[[Page 28343]]
commenters expected States generally to be able to do so, while one
suggested that EPA issue such permits because States will lack the
authority to do so without protracted rule revisions. One of these
commenters also suggested that we revise appendix S to authorize
interprecursor trading during the transition period, believing that the
paucity of existing direct PM2.5 emissions and SO2 offsets likely will
make business expansion in PM2.5 nonattainment areas from now until at
least April 2008 impossible unless this is done. One commenter
suggested that we suspend the 2005 PM2.5 NSR guidance which allows use
of PM10 emissions as a surrogate for PM2.5 emissions in PM2.5
nonattainment areas when we adopt the final PM2.5 implementation rules,
while three other commenters requested continued implementation of that
guidance during the interim period.
As noted previously, this final action will require States to amend
their NA NSR programs consistent with the amended rules at 40 CFR
51.165. During the SIP development period, where they have legal
authority to do so, States must issue NA NSR permits under appendix S
(as revised for purposes of the PM2.5 program). To address one of the
points raised by commenters, we are amending appendix S to allow
interpollutant trading for PM2.5 in this final rule. Where a State
determines that it does not have legal authority to issue such permits,
we will act as the reviewing authority. As of the effective date of
this action, the 2005 PM2.5 NSR guidance on use of PM10 emissions as a
surrogate for PM2.5 emissions will remain in effect only for PSD in the
SIP-approved States during the SIP development period. In the delegated
PSD States and in nonattainment areas, the new PM2.5 requirements will
apply immediately on the effective date of this final action.
J. Does major NSR apply to PM2.5 precursors during the SIP development
period?
As discussed previously in section V.A, we have taken final action
on NSR applicability for PM2.5 precursors. Specifically, we have
designated SO2 as a national precursor to PM2.5 in all areas, NOX as a
``presumed-in'' precursor in all areas, VOC as a ``presumed-out''
precursor in all areas, and ammonia as a ``presumed-out'' precursor.
Thus, States have the option of excluding NOX as a precursor by
demonstrating that NOX emissions are not a significant contributor to
ambient PM2.5 concentrations in a particular area. In addition, States
have the option of identifying VOC and/or ammonia as precursor(s) by
demonstrating that emissions of VOC and/or ammonia are a significant
contributor in an area, and thus should be subject to major NSR.
In the proposal, during the SIP development period, we proposed
that SO2 should be treated as a regulated PM2.5 precursor as of the
effective date of this final rule since there is no doubt about its
status as such in any area and proposed to defer NSR applicability for
NOX until a State SIP submittal so that if a State elected to submit
information to rebut the presumption that NOX is a regulated PM2.5
precursor, the State would have an opportunity to do so in its SIP
submittal. We also proposed that VOCs and ammonia would not be treated
as PM2.5 precursors during the interim period because they are presumed
not to be precursors until they have been demonstrated to be through a
State's SIP submittal.
A few commenters supported staying the applicability of NSR to all
precursors during the interim period. However, two of these supporters
suggested that EPA establish mechanisms for interpollutant trading for
offsets during the interim period so that increases in direct PM2.5
emissions can be offset with SO2 or NOX emissions reductions. Another
supporter noted that their State cannot impose obligations on NSR
applicants until those obligations are established in State regulations
or statutes. Another indicated that this delay would allow States the
time to develop experience and knowledge in establishing local
photochemical models and to performance test their accuracy.
Two commenters opposed staying NSR applicability for any
precursors. They believe that this would make attainment more
difficult. One commenter suggested that SO2 should be designated as a
precursor during the interim period, and another suggested the same for
SO2 and NOX.
Based on the comments, we have been persuaded that SIP-approved PSD
States will not have the authority to regulate PM2.5 precursors before
they have amended their SIPs to incorporate these requirements in
attainment areas. Thus, in order to allow time for these States to
revise their regulations to incorporate such requirements, this final
action does not require regulation of SO2 or NOX as precursors to PM2.5
under PSD until the SIP development period ends. In addition, we are
allowing SIP-approved PSD States to continue with the existing PM10
surrogate policy to meet the PSD requirements for PM2.5. However, for
delegated PSD States, SO2 and NOX are regulated as precursors from the
effective date of this rule. However, these States or EPA have the
option of excluding NOX as a precursor by demonstrating that NOX
emissions are not a significant contributor to ambient PM2.5
concentrations in a particular area.
For nonattainment areas, the transitional program pursuant to
appendix S will apply on the effective date of this action. Under
appendix S, SO2 will be regulated as a precursor in all nonattainment
areas for PM2.5. However, unlike in the proposal, NOX will not be
regulated as a precursor for PM2.5 because we believe it is appropriate
to give States the opportunity to determine whether NOX emissions are a
significant contributor to the ambient PM2.5 problem, and to make the
appropriate demonstration in their SIP. Finally, for States determining
that VOC and/or ammonia are PM2.5 precursors under their SIPs, we will
approve their definition of ``significant emissions rate'' for each
precursor based on an appropriate demonstration.
K. Are there any Tribal concerns?
Some Tribal areas may be designated as nonattainment, in part
because of pollution that is transported from surrounding State lands.
Tribal representatives have advocated for additional flexibility to
address nonattainment problems caused by transported pollution, such as
a pool of available NSR offset set-asides (which we expect would come
from State offset pools or banks), because they have limited ability to
generate offsets on their own. Tribal representatives have raised these
and other concerns in discussions on implementation of the 8-hour ozone
and PM2.5 standards, and in comments on the 8-hour ozone implementation
rule. We requested comment on whether emissions offset set-asides,
possibly generated by innovative measures to promote additional
emissions reductions, are an appropriate method to help level the
playing field for the Tribes and support economic development in Tribal
areas. We also requested comment on ways in which States may help
provide the Tribes access to offsets from non-Tribal areas. We received
no comments on these issues.
We recently proposed Tribal NSR rules. See 71 FR 48696, August 21,
2006. They include a NA NSR rule, which refers to appendix S for its
substantive requirements, and a minor NSR rule. In recognition of the
concerns mentioned above, we have proposed and sought comments on
options for obtaining offset relief in that proposal.
[[Page 28344]]
We will address these issues in the context of that rule.
L. What are the requirements for minor NSR for PM2.5?
Pursuant to section 110(a)(2)(C) of the Act, States must have a
minor source permitting program. This applies to new and modified
stationary sources that are not considered major for a criteria
pollutant or a precursor for a criteria pollutant. Prior to this
action, States were required to include the following pollutants in
their minor NSR program:
VOC,
SO2,
NOX,
CO,
PM10, and
Lead (Pb).
Based on this action, States must now amend their minor source
programs to include direct PM2.5 emissions and precursor emissions in
the same manner as included for purposes of PM2.5 major NSR.
M. Rural Transport Areas
In the proposal for the Clean Air Fine Particle Implementation Rule
and this NSR implementation rule for PM2.5, we considered the option of
classifying some nonattainment areas as transport areas that suffer
from overwhelming transport, and of developing NA NSR rules specific to
such areas. However, the final implementation rule does not include the
rural transport classification. Consequently, no NA NSR rules have been
developed or finalized in this rule.
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993),
this action is a ``significant regulatory action'' because it is likely
to raise novel legal or policy issues arising out of legal mandates,
the President's priorities, or the principles set forth in the
Executive Order. Accordingly, EPA submitted this action to the Office
of Management and Budget (OMB) for review under EO 12866 and any
changes made in response to OMB recommendations have been documented in
the docket for this action.
B. Paperwork Reduction Act
The information collection requirements in this rule have been
submitted for approval to the OMB under the Paperwork Reduction Act, 44
U.S.C. 3501 et seq. The information collection requirements are not
enforceable until OMB approves them. The Information Collection Request
(ICR) document prepared by EPA has been assigned OMB Control Number
2060-0003 (EPA ICR No. 1230.21).
To achieve the purposes of the major NSR program, certain records
and reports are necessary for the State or local agency (or the EPA
Administrator in non-delegated States), for example, to: (1) Confirm
the compliance of status of stationary sources, identify any stationary
sources not subject to the rules, and identify stationary sources
subject to the rules; and (2) ensure that the stationary source control
requirements are being achieved. The information would be used by EPA
or State enforcement personnel to (1) identify stationary sources
subject to the rules, (2) ensure that appropriate control technology is
being properly applied, and (3) ensure that the emission control
devices are being properly operated and maintained on a continuous
basis.
This final NSR rule does not create new information collection
requirements, but rather expands the coverage of the existing
requirements of the major NSR program. Specifically, the rule changes
finalized in this action add PM2.5 to the list of air pollutants that
must be addressed in the major NSR program, and the companion proposal
adds certain elements that are necessary for a complete PM2.5 NSR
program. This change is unlikely to increase significantly the number
of NSR permits that must be issued, but may add to the analyses that
sources and Federal, State, and local reviewing authorities must
conduct as part of the construction permit application and review
process.
We expect the rule changes finalized in this action to increase the
burden associated with major NSR permitting for tracking new emissions
of PM2.5 against increments; collecting ambient air quality monitoring
data for existing PM2.5 concentrations; reviewing the effects of PM2.5
emissions on soils and vegetation, as well as on air quality related
values in Class I areas; determining the appropriate best available
control technology or lowest achievable emission rate; and/or obtaining
offsets. At the same time, there would be a reduction in burden
directly associated with the revocation of the annual increment for
PM10, which is proposed in the proposed rule.
Over the 3-year period covered by the ICR, we estimate an average
annual burden increase of about 39,000 hours (about 8 percent) and $4.3
million (about 10 percent) for all industry entities that would be
affected by this final NSR rule. For the same reasons, we also expect
the final rule to increase burden for the State and local authorities
reviewing permit applications when fully implemented. In addition,
there would be additional burden for State and local agencies to revise
their SIPs to incorporate the proposed changes. We estimate the
combined increase in burden to average about 16,000 hours and $700,000
annually for all State and local reviewing authorities, which is less
than 13 percent.
Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9. When this ICR is
approved by OMB, the Agency will publish a technical amendment to 40
CFR part 9 in the Federal Register to display the OMB control number
for the approved information collection requirements contained in this
final rule.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the Agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
For purposes of assessing the impacts of this proposed rule on
small entities, ``small entity'' is defined as: (1) A small business as
defined by the Small Business Administration's regulations at 13 CFR
121.201; (2) a small governmental jurisdiction that is a government or
a city, county, town,
[[Page 28345]]
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and is not
dominant in its field.
After considering the economic impacts of this final rule on small
entities, I certify that this rule will not have a significant economic
impact on a substantial number of small entities. The requirements of
this final rule apply only to new major stationary sources or major
modifications of existing major stationary sources. This final rule
does not create any new requirements under the major NSR program, but
simply expands the program to cover an additional pollutant, referred
to as PM2.5. There is no reason to expect that the rule will
significantly or uniquely affect small businesses, organizations, or
governments (few, if any, of which act as reviewing authorities
pursuant to this final rule).
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, we
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
aggregate, or to the private sector, of $100 million or more in any 1
year. Before promulgating an EPA rule for which a written statement is
needed, section 205 of the UMRA generally requires us to identify and
consider a reasonable number of regulatory alternatives and adopt the
least costly, most cost-effective, or least burdensome alternative that
achieves the objectives of the rule. The provisions of section 205 do
not apply when they are inconsistent with applicable law. Moreover,
section 205 allows us to adopt an alternative other than the least-
costly, most cost-effective, or least-burdensome alternative if the
Administrator publishes with the final rule an explanation of why that
alternative was not adopted. Before we establish any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, we must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of our regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
We have determined that this rule does not contain a Federal
mandate that may result in expenditures of $100 million or more for
State, local, and tribal governments, in the aggregate, or the private
sector in any 1 year. The final rule does not add any new requirements
to the NSR program; it simply expands the program to cover
PM2.5 in addition to the several other pollutants already
defined as regulated NSR pollutants. (Technically, the rule also
subjects the precursors to PM2.5 to the NSR program.
However, these precursors (SO2, NOX, and VOC) are
already subject to the existing NSR program.) As discussed previously
in section VI.B on the Paperwork Reduction Act, the expansion of the
NSR program to cover PM2.5 will only marginally increase the
expenditures of State, local, and tribal governments and the private
sector on the program. Thus, this action is not subject to the
requirements of sections 202 and 205 of the UMRA.
The EPA has determined that this rule contains no regulatory
requirements that might significantly or uniquely affect small
governments. As noted previously, this rule does not create any new
requirements under the major NSR program, but simply expands the
program to cover an additional pollutant (PM2.5). There is
no reason to expect that the rule will significantly or uniquely affect
small governments, few if any of which act as reviewing authorities.
E. Executive Order 13132--Federalism
Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires us to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
This final rule does not have federalism implications. It will not
have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. Pursuant to the terms of
Executive Order 13132, it has been determined that this proposed rule
does not have ``federalism implications'' because it does not meet the
necessary criteria. Thus, the requirements of section 6 of the
Executive Order do not apply to this proposed rule.
In the spirit of Executive Order 13132, however, and consistent
with our policy to promote communications between us and State and
local governments, we specifically solicited comment on the proposed
rule from State and local officials.
F. Executive Order 13175--Consultation and Coordination With Indian
Tribal Governments
Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by Tribal officials in the development of regulatory
policies that have Tribal implications.'' This final rule does not have
``Tribal implications'' as defined in Executive Order 13175. This rule
concerns the NSR requirements for State and tribal implementation
plans. The CAA provides for States to develop plans to regulate
emissions of air pollutants within their jurisdictions. The Tribal Air
Rule (TAR) under the CAA gives Tribes the opportunity to develop and
implement CAA programs such as programs to attain and maintain the
PM2.5 NAAQS, but it leaves to the discretion of the Tribe
the decision of whether to develop these programs and which programs,
or appropriate elements of a program, they will adopt.
Although Executive Order 13175 does not apply to this rule, EPA did
reach out to Tribal leaders and environmental staff in developing this
rule. From 2001-2004, the EPA supported a National Designations
Workgroup to provide a forum for tribal professionals to give input to
the designations process. In 2006, EPA supported a national ``Tribal
Air call'' which provides an open forum for all Tribes to voice
concerns to EPA about the NAAQS implementation process, including the
PM2.5 NAAQS. In these meetings, EPA briefed call
participants and Tribal environmental professionals gave input as the
rule was under development. Furthermore, in December 2005, EPA sent
individualized letters to all federally recognized Tribes about the
proposal to give Tribal leaders the opportunity for consultation.
This final rule does not have Tribal implications as defined by
Executive
[[Page 28346]]
Order 13175. It does not have a substantial direct effect on one or
more Indian Tribes, since no Tribe has implemented a CAA program to
attain the PM2.5 NAAQS at this time. The EPA notes that even
if a Tribe were implementing such a plan at this time, while the rule
might have Tribal implications with respect to that Tribe, it would not
impose substantial direct costs upon it, nor would it preempt Tribal
law.
Furthermore, this rule does not affect the relationship or
distribution of power and responsibilities between the Federal
government and Indian Tribes. The CAA and the TAR establish the
relationship of the Federal government and Tribes in developing plans
to attain the NAAQS, and this rule does nothing to modify that
relationship. As this rule does not have Tribal implications, Executive
Order 13175 does not apply.
G. Executive Order 13045--Protection of Children From Environmental
Health and Safety Risks
Executive Order 13045, entitled ``Protection of Children from
Environmental Health Risks and Safety Risks'' (62 FR 19885, April 23,
1997), applies to any rule that: (1) Is determined to be ``economically
significant'' as defined under Executive Order 12866; and (2) concerns
an environmental health or safety risk that we have reason to believe
may have a disproportionate effect on children. If the regulatory
action meets both criteria, the Agency must evaluate the environmental
health or safety effects of the planned rule on children, and explain
why the planned regulation is preferable to other potentially effective
and reasonably feasible alternatives considered by the Agency.
This final rule is not subject to the Executive Order because it is
not economically significant as defined in Executive Order 12866, and
because the Agency does not have reason to believe the environmental
health or safety risks addressed by this action present a
disproportionate risk to children. This rule does not impose any new
requirements under the NSR program. However, in expanding the major NSR
program to address PM2.5, we believe that this rule will
serve to reduce environmental health risks to all citizens, including
children, because one of the basic requirements of the major NSR
program is that new and modified major stationary sources must not
cause or contribute to air quality in violation of the NAAQS.
H. Executive Order 13211--Actions That Significantly Affect Energy
Supply, Distribution, or Use
This rule is not a ``significant energy action'' as defined in
Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355
(May 22, 2001)) because it is not likely to have a significant adverse
effect on the supply, distribution, or use of energy. The final rule
does not add any new requirements to the major NSR program; it simply
expands the program to cover PM2.5 in addition to the
several other pollutants already defined as regulated NSR pollutants.
Although the major NSR program may apply to energy supply and
distribution companies that build or significantly modify major sources
of regulated NSR pollutants, we believe that any increase in
expenditures for obtaining NSR permits that may result from this rule
will be marginal rather than significant.
I. National Technology Transfer and Advancement Act
As noted in the proposed rule, section 12(d) of the National
Technology Transfer and Advancement Act of 1995 (NTTAA), Public Law No.
104-113, 12(d) (15 U.S.C. 272 note) directs us to use voluntary
consensus standards (VCS) in our regulatory and procurement activities
unless to do so would be inconsistent with applicable law or otherwise
impractical. The VCS are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) developed or adopted by one or more voluntary consensus
bodies. The NTTAA directs us to provide Congress, through annual
reports to OMB, with explanations when we do not use available and
applicable VCS.
This final rule does not involve technical standards. Therefore, we
did not consider the use of any VCS.
J. Executive Order 12898--Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations
Executive Order 12898 (59 FR 7629 (Feb. 16, 1994)) establishes
Federal executive policy on environmental justice. Its main provision
directs Federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of its programs,
policies, and activities on minorities and low-income populations in
the United States.
The EPA has determined that this final rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it will have the
effect of improving air quality. While it does not impose any new
requirements under the major NSR program, we believe that this rule, in
expanding the NSR program to address PM2.5, will serve to
reduce adverse human health and environmental effects for all citizens,
including minorities and low-income populations.
K. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. The EPA will submit a report containing this rule and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). The rules affected by this action will be effective July 15,
2008.
L. Petitions for Judicial Review
Under section 307(b)(1) of the Act, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the District of Columbia Circuit by July 15, 2008. Filing a petition
for reconsideration by the Administrator of this final rule does not
affect the finality of this rule for the purposes of judicial review
nor does it extend the time within which a petition for judicial review
may be filed, and shall not postpone the effectiveness of such rule or
action. This action may not be challenged later in proceedings to
enforce its requirements. See Act section 307(b)(2).
M. Determination Under Section 307(d)
The PSD portions of this rulemaking, which implements part C of
title I of the Act, are subject to the procedural requirements in
section 307(d) of the Act. See section 307(d)(1)(J). In addition,
pursuant to section 307(d)(1)(V) of the Act, the Administrator
determines that the NA
[[Page 28347]]
NSR portions of this action should also be subject to the provisions of
section 307(d) to ensure consistency. All of the procedural
requirements of section 307(d), e.g., docketing, hearing, and comment
periods, have been complied with during the course of this rulemaking.
VII. Statutory Authority
The statutory authority for this action is provided by sections
101, 110, 165, 169, 172, 173, 301, and 302 of the Act as amended (42
U.S.C. 7401, 7410, 7475, 7479, 7502, 7503, 7601, and 7602). This
rulemaking is also subject to section 307(d) of the Act (42 U.S.C.
7407(d)).
List of Subjects
40 CFR Part 51
Environmental protection, Administrative practices and procedures,
Air pollution control, Intergovernmental relations.
40 CFR Part 52
Environmental protection, Administrative practices and procedures,
Air pollution control, Intergovernmental relations.
Dated: May 8, 2008.
Stephen L. Johnson,
Administrator.
0
For the reasons stated in the preamble, title 40, chapter I of the Code
of Federal Regulations is amended as follows.
PART 51--[AMENDED]
0
1. The authority citation for part 51 continues to read as follows:
Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.
Subpart I--[Amended]
0
2. Section 51.165 is amended as follows:
0
a. By revising paragraph (a)(1)(x)(A);
0
b. By removing the word ``or'' at the end of paragraph
(a)(1)(xxxvii)(B);
0
c. By revising paragraph (a)(1)(xxxvii)(C);
0
d. By adding paragraph (a)(1)(xxxvii)(D);
0
e. By redesignating paragraphs (a)(9)(i) through (iii) as paragraphs
(a)(9)(ii) through (iv), respectively, and adding new paragraph
(a)(9)(i);
0
f. By removing from newly redesignated paragraph (a)(9)(iii) the
reference to ``paragraph (a)(9)(i)'' and adding in its place
``paragraph (a)(9)(ii)''; and
0
g. By adding paragraph (a)(11).
Sec. 51.165 Permit requirements.
(a) * * *
(1) * * *
(x)(A) Significant means, in reference to a net emissions increase
or the potential of a source to emit any of the following pollutants, a
rate of emissions that would equal or exceed any of the following
rates:
Pollutant Emission Rate
Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Ozone: 40 tpy of volatile organic compounds or nitrogen oxides
Lead: 0.6 tpy
PM10: 15 tpy
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy
of sulfur dioxide emissions; 40 tpy of nitrogen oxide emissions unless
demonstrated not to be a PM2.5 precursor under paragraph
(a)(1)(xxxvii) of this section
* * * * *
(xxxvii) * * *
(C) Any pollutant that is identified under this paragraph
(a)(1)(xxxvii)(C) as a constituent or precursor of a general pollutant
listed under paragraph (a)(1)(xxxvii)(A) or (B) of this section,
provided that such constituent or precursor pollutant may only be
regulated under NSR as part of regulation of the general pollutant.
Precursors identified by the Administrator for purposes of NSR are the
following:
(1) Volatile organic compounds and nitrogen oxides are precursors
to ozone in all ozone nonattainment areas.
(2) Sulfur dioxide is a precursor to PM2.5 in all
PM2.5 nonattainment areas.
(3) Nitrogen oxides are presumed to be precursors to
PM2.5 in all PM2.5 nonattainment areas, unless
the State demonstrates to the Administrator's satisfaction or EPA
demonstrates that emissions of nitrogen oxides from sources in a
specific area are not a significant contributor to that area's ambient
PM2.5 concentrations.
(4) Volatile organic compounds and ammonia are presumed not to be
precursors to PM2.5 in any PM2.5 nonattainment
area, unless the State demonstrates to the Administrator's satisfaction
or EPA demonstrates that emissions of volatile organic compounds or
ammonia from sources in a specific area are a significant contributor
to that area's ambient PM2.5 concentrations; or
(D) PM2.5 emissions and PM10 emissions shall
include gaseous emissions from a source or activity which condense to
form particulate matter at ambient temperatures. On or after January 1,
2011 (or any earlier date established in the upcoming rulemaking
codifying test methods), such condensable particulate matter shall be
accounted for in applicability determinations and in establishing
emissions limitations for PM2.5 and PM10 in
nonattainment major NSR permits. Compliance with emissions limitations
for PM2.5 and PM10 issued prior to this date
shall not be based on condensable particulate matter unless required by
the terms and conditions of the permit or the applicable implementation
plan. Applicability determinations made prior to this date without
accounting for condensable particulate matter shall not be considered
in violation of this section unless the applicable implementation plan
required condensable particulate matter to be included.
* * * * *
(9)(i) The plan shall require that in meeting the emissions offset
requirements of paragraph (a)(3) of this section, the ratio of total
actual emissions reductions to the emissions increase shall be at least
1:1 unless an alternative ratio is provided for the applicable
nonattainment area in paragraphs (a)(9)(ii) through (a)(9)(iv) of this
section.
* * * * *
(11) The plan shall require that in meeting the emissions offset
requirements of paragraph (a)(3) of this section, the emissions offsets
obtained shall be for the same regulated NSR pollutant unless
interprecursor offsetting is permitted for a particular pollutant as
specified in this paragraph. The plan may allow the offset requirements
in paragraph (a)(3) of this section for direct PM2.5
emissions or emissions of precursors of PM2.5 to be
satisfied by offsetting reductions in direct PM2.5 emissions
or emissions of any PM2.5 precursor identified under
paragraph (a)(1)(xxxvii)(C) of this section if such offsets comply with
the interprecursor trading hierarchy and ratio established in the
approved plan for a particular nonattainment area.
* * * * *
0
3. Section 51.166 is amended as follows:
0
a. By revising paragraphs (b)(23)(i) and (b)(49)(i);
0
b. By removing the word ``or'' at the end of paragraph (b)(49)(iii);
0
c. By adding and reserving paragraph (b)(49)(v);
0
d. By adding paragraph (b)(49)(vi); and
0
e. By revising paragraphs (i)(5)(ii) and (i)(5)(iii).
[[Page 28348]]
Sec. 51.166 Prevention of significant deterioration of air quality.
* * * * *
(b) * * *
(23)(i) Significant means, in reference to a net emissions increase
or the potential of a source to emit any of the following pollutants, a
rate of emissions that would equal or exceed any of the following
rates:
Pollutant and Emissions Rate
Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Particulate matter: 25 tpy of particulate matter emissions. 15 tpy of
PM10 emissions
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy
of sulfur dioxide emissions; 40 tpy of nitrogen oxide emissions unless
demonstrated not to be a PM2.5 precursor under paragraph
(b)(49) of this section
Ozone: 40 tpy of volatile organic compounds or nitrogen oxides
Lead: 0.6 tpy
Fluorides: 3 tpy
Sulfuric acid mist: 7 tpy
Hydrogen sulfide (H2S): 10 tpy
Total reduced sulfur (including H2S): 10 tpy
Reduced sulfur compounds (including H2S): 10 tpy
Municipal waste combustor organics (measured as total tetra-through
octa-chlorinated dibenzo-p-dioxins and dibenzofurans): 3.2 x 10-
-6 megagrams per year (3.5 x 10-6 tons per year)
Municipal waste combustor metals (measured as particulate matter): 14
megagrams per year (15 tons per year)
Municipal waste combustor acid gases (measured as sulfur dioxide and
hydrogen chloride): 36 megagrams per year (40 tons per year)
Municipal solid waste landfill emissions (measured as nonmethane
organic compounds): 45 megagrams per year (50 tons per year)
* * * * *
(49) * * *
(i) Any pollutant for which a national ambient air quality standard
has been promulgated and any pollutant identified under this paragraph
(b)(49)(i) as a constituent or precursor to such pollutant. Precursors
identified by the Administrator for purposes of NSR are the following:
(a) Volatile organic compounds and nitrogen oxides are precursors
to ozone in all attainment and unclassifiable areas.
(b) Sulfur dioxide is a precursor to PM2.5 in all
attainment and unclassifiable areas.
(c) Nitrogen oxides are presumed to be precursors to
PM2.5 in all attainment and unclassifiable areas, unless the
State demonstrates to the Administrator's satisfaction or EPA
demonstrates that emissions of nitrogen oxides from sources in a
specific area are not a significant contributor to that area's ambient
PM2.5 concentrations.
(d) Volatile organic compounds are presumed not to be precursors to
PM2.5 in any attainment or unclassifiable area, unless the
State demonstrates to the Administrator's satisfaction or EPA
demonstrates that emissions of volatile organic compounds from sources
in a specific area are a significant contributor to that area's ambient
PM2.5 concentrations.
* * * * *
(v) [Reserved.]
(vi) Particulate matter (PM) emissions, PM2.5 emissions,
and PM10 emissions shall include gaseous emissions from a
source or activity which condense to form particulate matter at ambient
temperatures. On or after January 1, 2011 (or any earlier date
established in the upcoming rulemaking codifying test methods), such
condensable particulate matter shall be accounted for in applicability
determinations and in establishing emissions limitations for PM,
PM2.5 and PM10 in PSD permits. Compliance with
emissions limitations for PM, PM2.5 and PM10
issued prior to this date shall not be based on condensable particular
matter unless required by the terms and conditions of the permit or the
applicable implementation plan. Applicability determinations made prior
to this date without accounting for condensable particular matter shall
not be considered in violation of this section unless the applicable
implementation plan required condensable particular matter to be
included.
* * * * *
(i) * * *
(5) * * *
(ii) The concentrations of the pollutant in the area that the
source or modification would affect are less than the concentrations
listed in paragraph (i)(5)(i) of this section; or
(iii) The pollutant is not listed in paragraph (i)(5)(i) of this
section.
* * * * *
0
4. Appendix S to Part 51 is amended as follows:
0
a. By revising paragraphs II.A.10(i) and II.A.31;
0
b. By revising paragraph IV.A, Condition 3;
0
c. By redesignating paragraphs IV.G.1 through IV.G.3 as paragraphs
IV.G.2 through IV.G.4, respectively, and adding new paragraph IV.G.1;
0
d. By removing from newly redesignated paragraph IV.G.3 the reference
to ``paragraph IV.G.1'' and adding in its place ``paragraph IV.G.2'';
and
0
e. By adding paragraph IV.G.5.
Appendix S to Part 51--Emission Offset Interpretative Ruling
* * * * *
II. * * *
A. * * *
10. (i) Significant means, in reference to a net emissions
increase or the potential of a source to emit any of the following
pollutants, a rate of emissions that would equal or exceed any of
the following rates:
Pollutant and Emissions Rate
Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Ozone: 40 tpy of volatile organic compounds or nitrogen oxides
Lead: 0.6 tpy
Particulate matter: 25 tpy of particulate matter emissions
PM10: 15 tpy
PM2.5: 10 tpy of direct PM2.5 emissions; 40
tpy of sulfur dioxide emissions
* * * * *
31. Regulated NSR pollutant, for purposes of this Ruling, means
the following:
(i) Nitrogen oxides or any volatile organic compounds;
(ii) Any pollutant for which a national ambient air quality
standard has been promulgated;
(iii) Any pollutant that is identified under this paragraph
II.A.31(iii) as a constituent or precursor of a general pollutant
listed under paragraph II.A.31(i) or (ii) of this Ruling, provided
that such constituent or precursor pollutant may only be regulated
under NSR as part of regulation of the general pollutant. Precursors
identified by the Administrator for purposes of NSR are the
following:
(a) Volatile organic compounds and nitrogen oxides are
precursors to ozone in all ozone nonattainment areas.
(b) Sulfur dioxide is a precursor to PM2.5 in all
PM2.5 nonattainment areas; or
(iv) Particulate matter (PM) emissions, PM2.5
emissions and PM10 emissions shall include gaseous
emissions from a source or activity which condense to form
particulate matter at ambient temperatures. On or after January 1,
2011 (or any earlier date established in the upcoming rulemaking
codifying test methods), such condensable particulate matter shall
be accounted for in applicability determinations and in establishing
emissions limitations for PM, PM2.5 and PM10
in permits issued under this ruling. Compliance with emissions
limitations for PM, PM2.5 and PM10 issued
prior to this date shall not be based on condensable particulate
matter unless required by the terms and conditions of the permit or
the applicable implementation plan. Applicability determinations
made prior to this date without accounting for condensable
particulate matter shall not be
[[Page 28349]]
considered in violation of this section unless the applicable
implementation plan required condensable particulate matter to be
included.
* * * * *
IV. * * *
A. * * *
Condition 3. Emission reductions (offsets) from existing sources
\5\ in the area of the proposed source (whether or not under the
same ownership) are required such that there will be reasonable
progress toward attainment of the applicable NAAQS.\6\ Except as
provided in paragraph IV.G.5 of this Ruling (addressing
PM2.5 and its precursors), only intrapollutant emission
offsets will be acceptable (e.g., hydrocarbon increases may not be
offset against SO2 reductions).
\5\ Subject to the provisions of paragraph IV.C of this Ruling.
\6\ The discussion in this paragraph is a proposal, but
represents EPA's interim policy until final rulemaking is completed.
* * * * *
G. Offset ratios.
1. In meeting the emissions offset requirements of paragraph
IV.A, Condition 3 of this Ruling, the ratio of total actual
emissions reductions to the emissions increase shall be at least 1:1
unless an alternative ratio is provided for the applicable
nonattainment area in paragraphs IV.G.2 through IV.G.4.
* * * * *
5. Interpollutant offsetting. In meeting the emissions offset
requirements of paragraph IV.A, Condition 3 of this Ruling, the
emissions offsets obtained shall be for the same regulated NSR
pollutant unless interpollutant offsetting is permitted for a
particular pollutant as specified in this paragraph IV.G.5. The
offset requirements of paragraph IV.A, Condition 3 of this Ruling
for direct PM2.5 emissions or emissions of precursors of
PM2.5 may be satisfied by offsetting reductions of direct
PM2.5 emissions or emissions of any PM2.5
precursor identified under paragraph II.A.31 (iii) of this Ruling if
such offsets comply with an interprecursor trading hierarchy and
ratio approved by the Administrator.
* * * * *
PART 52--[AMENDED]
0
5. The authority citation for part 52 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
Subpart A--[Amended]
0
6. Section 52.21 is amended as follows:
0
a. By revising paragraphs (b)(23)(i) and (b)(50)(i);
0
b. By removing the word ``or'' at the end of paragraph (b)(50)(iii);
0
c. By adding and reserving paragraph (b)(50)(v);
0
d. By adding paragraphs (b)(50)(vi) and (i)(1)(xi);
0
e. By revising paragraph (i)(5)(ii); and
0
f. By adding paragraph (i)(5)(iii).
Sec. 52.21 Prevention of significant deterioration of air quality.
* * * * *
(b) * * *
(23)(i) Significant means, in reference to a net emissions increase
or the potential of a source to emit any of the following pollutants, a
rate of emissions that would equal or exceed any of the following
rates:
Pollutant and Emissions Rate
Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Particulate matter: 25 tpy of particulate matter emissions
PM10: 15 tpy
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy
of sulfur dioxide emissions; 40 tpy of nitrogen oxide emissions unless
demonstrated not to be a PM2.5 precursor under paragraph
(b)(50) of this section
Ozone: 40 tpy of volatile organic compounds or nitrogen oxides
Lead: 0.6 tpy
Fluorides: 3 tpy
Sulfuric acid mist: 7 tpy
Hydrogen sulfide (H2S): 10 tpy
Total reduced sulfur (including H2S): 10 tpy
Reduced sulfur compounds (including H2S): 10 tpy
Municipal waste combustor organics (measured as total tetra-through
octa-chlorinated dibenzo-p-dioxins and dibenzofurans): 3.2 x 10 \-6\
megagrams per year (3.5 x 10 \-6\ tons per year)
Municipal waste combustor metals (measured as particulate matter): 14
megagrams per year (15 tons per year)
Municipal waste combustor acid gases (measured as sulfur dioxide and
hydrogen chloride): 36 megagrams per year (40 tons per year)
Municipal solid waste landfills emissions (measured as nonmethane
organic compounds): 45 megagrams per year (50 tons per year)
* * * * *
(50) * * *
(i) Any pollutant for which a national ambient air quality standard
has been promulgated and any pollutant identified under this paragraph
(b)(50)(i) as a constituent or precursor for such pollutant. Precursors
identified by the Administrator for purposes of NSR are the following:
(a) Volatile organic compounds and nitrogen oxides are precursors
to ozone in all attainment and unclassifiable areas.
(b) Sulfur dioxide is a precursor to PM2.5 in all
attainment and unclassifiable areas.
(c) Nitrogen oxides are presumed to be precursors to
PM2.5 in all attainment and unclassifiable areas, unless the
State demonstrates to the Administrator's satisfaction or EPA
demonstrates that emissions of nitrogen oxides from sources in a
specific area are not a significant contributor to that area's ambient
PM2.5 concentrations.
(d) Volatile organic compounds are presumed not to be precursors to
PM2.5 in any attainment or unclassifiable area, unless the
State demonstrates to the Administrator's satisfaction or EPA
demonstrates that emissions of volatile organic compounds from sources
in a specific area are a significant contributor to that area's ambient
PM2.5 concentrations.
* * * * *
(v) [Reserved.]
(vi) Particulate matter (PM) emissions, PM2.5 emissions
and PM10 emissions shall include gaseous emissions from a
source or activity which condense to form particulate matter at ambient
temperatures. On or after January 1, 2011 (or any earlier date
established in the upcoming rulemaking codifying test methods), such
condensable particulate matter shall be accounted for in applicability
determinations and in establishing emissions limitations for PM,
PM2.5 and PM10 in PSD permits. Compliance with
emissions limitations for PM, PM2.5 and PM10
issued prior to this date shall not be based on condensable particular
matter unless required by the terms and conditions of the permit or the
applicable implementation plan. Applicability determinations made prior
to this date without accounting for condensable particular matter shall
not be considered in violation of this section unless the applicable
implementation plan required condensable particular matter to be
included.
* * * * *
(i) * * *
(1) * * *
(xi) The source or modification was subject to 40 CFR 52.21, with
respect to PM2.5, as in effect before July 15, 2008, and the
owner or operator submitted an application for a permit under this
section before that date consistent with EPA recommendations to use
PM10 as a surrogate for PM2.5, and the
Administrator subsequently determines that the application as submitted
was complete with respect to the PM2.5 requirements then in
effect, as interpreted in the EPA memorandum entitled ``Interim
Implementation of New Source Review Requirements for PM2.5''
(October 23, 1997). Instead, the requirements of paragraphs (j) through
[[Page 28350]]
(r) of this section, as interpreted in the aforementioned memorandum,
that were in effect before July 15, 2008 shall apply to such source or
modification.
* * * * *
(5) * * *
(ii) The concentrations of the pollutant in the area that the
source or modification would affect are less than the concentrations
listed in paragraph (i)(5)(i) of this section; or
(iii) The pollutant is not listed in paragraph (i)(5)(i) of this
section.
* * * * *
[FR Doc. E8-10768 Filed 5-15-08; 8:45 am]
BILLING CODE 6560-50-P