[Code of Federal Regulations]
[Title 40, Volume 2]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR51.150]

[Page 163-164]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 51--REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF 
IMPLEMENTATION PLANS--Table of Contents
 
        Subpart H--Prevention of Air Pollution Emergency Episodes
 
Sec. 51.150  Classification of regions for episode plans.

    Source: 51 FR 40668, Nov. 7, 1986, unless otherwise noted.


    (a) This section continues the classification system for episode 
plans. Each region is classified separately with respect to each of the 
following pollutants: Sulfur oxides, particulate matter, carbon 
monoxide, nitrogen dioxide, and ozone.
    (b) Priority I Regions means any area with greater ambient 
concentrations than the following:
    (1) Sulfur dioxide--100 [mu]g/m\3\ (0.04 ppm) annual arithmetic 
mean; 455 [mu]g/m\3\ (0.17 ppm) 24-hour maximum.
    (2) Particulate matter--95 [mu]g/m\3\ annual geometric mean; 325 
[mu]g/m\3\ 24-hour maximum.

[[Page 164]]

    (3) Carbon monoxide--55 mg/m\3\ (48 ppm) 1-hour maximum; 14 mg/m\3\ 
(12 ppm) 8-hour maximum.
    (4) Nitrogen dioxide--100 [mu]g/m\3\ (0.06 ppm) annual arithmetic 
mean.
    (5) Ozone--195 [mu]g/m\3\ (0.10 ppm) 1-hour maximum.
    (c) Priority IA Region means any area which is Priority I primarily 
because of emissions from a single point source.
    (d) Priority II Region means any area which is not a Priority I 
region and has ambient concentrations between the following:
    (1) Sulfur Dioxides--60-100 [mu]g/m\3\ (0.02-0.04 ppm) annual 
arithmetic mean; 260-445 [mu]g/m\3\ (0.10-0.17 ppm) 24-hour maximum; any 
concentration above 1,300 [mu]g/m\3\ (0.50 ppm) three-hour average.
    (2) Particulate matter--60-95 [mu]g/m\3\ annual geometric mean; 150-
325 [mu]g/m\3\ 24-hour maximum.
    (e) In the absence of adequate monitoring data, appropriate models 
must be used to classify an area under paragraph (b) of this section, 
consistent with the requirements contained in Sec. 51.112(a).
    (f) Areas which do not meet the above criteria are classified 
Priority III.

[51 FR 40668, Nov. 7, 1986, as amended at 58 FR 38822, July 20, 1993]