40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

§ 50.17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

(a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75 parts per billion (ppb, which is 1 part in 1,000,000,000), measured in the ambient air as sulfur dioxide (SO2).

(b) The 1-hour primary standard is met at an ambient air quality monitoring site when the three-year average of the annual (99th percentile) of the daily maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined in accordance with appendix T of this part.

(c) The level of the standard shall be measured by a reference method based on appendix A or A-1 of this part, or by a Federal Equivalent Method (FEM) designated in accordance with part 53 of this chapter.

[ 75 FR 35592, June 22, 2010]

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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.

  • 2017-04-14; vol. 82 # 71 - Friday, April 14, 2017
    1. 82 FR 17947 - Release of the Policy Assessment for the Review of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen
      GPO FDSys XML | Text
      Notice of availability.
      The NO 2 PA will be available on or about April 12, 2017.
      40 CFR Parts 50 and 58
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