[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: 40CFR50.7]

[Page 7-8]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS--Table 
of Contents
 
Sec. 50.7   National primary and secondary ambient air quality standards 
for particulate matter.

    (a) The national primary and secondary ambient air quality standards 
for particulate matter are:
    (1) 15.0 micrograms per cubic meter ([mu]g/m\3\) annual arithmetic 
mean concentration, and 65 [mu]g/m\3\ 24-hour average concentration 
measured in the ambient air as PM2.5 (particles with an 
aerodynamic diameter less than or equal to a nominal 2.5 micrometers) by 
either:
    (i) A reference method based on appendix L of this part and 
designated in accordance with part 53 of this chapter; or
    (ii) An equivalent method designated in accordance with part 53 of 
this chapter.

[[Page 8]]

    (2) 50 micrograms per cubic meter ([mu]g/m\3\) annual arithmetic 
mean concentration, and 150 [mu]g/m\3\ 24-hour average concentration 
measured in the ambient air as PM10 (particles with an 
aerodynamic diameter less than or equal to a nominal 10 micrometers) by 
either:
    (i) A reference method based on appendix M of this part and 
designated in accordance with part 53 of this chapter; or
    (ii) An equivalent method designated in accordance with part 53 of 
this chapter.
    (b) The annual primary and secondary PM2.5 standards are 
met when the annual arithmetic mean concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 15.0 
micrograms per cubic meter.
    (c) The 24-hour primary and secondary PM2.5 standards are 
met when the 98th percentile 24-hour concentration, as 
determined in accordance with appendix N of this part, is less than or 
equal to 65 micrograms per cubic meter.
    (d) The annual primary and secondary PM10 standards are 
met when the annual arithmetic mean concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 50 
micrograms per cubic meter.
    (e) The 24-hour primary and secondary PM10 standards are 
met when the 99th percentile 24-hour concentration, as 
determined in accordance with appendix N of this part, is less than or 
equal to 150 micrograms per cubic meter.

[62 FR 38711, July 18, 1997]