40 CFR 50.7 - National primary and secondary ambient air quality standards for PM2.5.

§ 50.7 National primary and secondary ambient air quality standards for PM2.5.

(a) The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter (µg/m 3) annual arithmetic mean concentration, and 65 µg/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:

(1) A reference method based on appendix L of this part and designated in accordance with part 53 of this chapter; or

(2) 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 98 th 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.

[ 62 FR 38711, July 18, 1997, as amended at 69 FR 45595, July 30, 2004]

This is a list of United States Code sections, Statutes at Large, Public Laws, and Presidential Documents, which provide rulemaking authority for this CFR Part.

This list is taken from the Parallel Table of Authorities and Rules provided by GPO [Government Printing Office].

It is not guaranteed to be accurate or up-to-date, though we do refresh the database weekly. More limitations on accuracy are described at the GPO site.


United States Code

Title 40 published on 2015-08-22

The following are ALL rules, proposed rules, and notices (chronologically) published in the Federal Register relating to 40 CFR Part 50 after this date.

  • 2017-03-28; vol. 82 # 58 - Tuesday, March 28, 2017
    1. 82 FR 15310 - Response to December 9, 2013, Clean Air Act Section 176A Petition From Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island and Vermont
      GPO FDSys XML | Text
      ENVIRONMENTAL PROTECTION AGENCY
      Notice of public hearing and extension of comment period.
      Comments. Comments must be received on or before May 15, 2017. Public Hearing. The public hearing will be held on April 13, 2017, in Washington, DC. Please refer to SUPPLEMENTARY INFORMATION section for additional information on the public hearing.
      40 CFR Parts 50 and 51