[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: 40CFR51.151]

[Page 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. 51.151  Significant harm levels.

    Each plan for a Priority I region must include a contingency plan 
which must, as a mimimum, provide for taking action necessary to prevent 
ambient pollutant concentrations at any location in such region from 
reaching the following levels:

Sulfur dioxide--2.620 [mu]g/m\3\ (1.0 ppm) 24-hour average.
PM10--600 micrograms/cubic meter; 24-hour average.
Carbon monoxide--57.5 mg/m\3\ (50 ppm) 8-hour average; 86.3 mg/m\3\ (75 
ppm) 4-hour average; 144 mg/m\3\ (125 ppm) 1-hour average.
Ozone--1,200 ug/m\3\ (0.6 ppm) 2-hour average.
Nitrogen dioxide--3.750 ug/m\3\ (2.0 ppm) 1-hour average; 938 ug/m\3\ 
(0.5 ppm) 24-hour average.

[51 FR 40668, Nov. 7, 1986, as amended at 52 FR 24713, July 1, 1987]