40 CFR 50.10 - National 8-hour primary and secondary ambient air quality standards for ozone.

Status message

There is 1 rule appearing in the Federal Register for 40 CFR Part 50. View below or at eCFR (GPOAccess)
§ 50.10 National 8-hour primary and secondary ambient air quality standards for ozone.
(a) The level of the national 8-hour primary and secondary ambient air quality standards for ozone, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter, is 0.08 parts per million (ppm), daily maximum 8-hour average.
(b) The 8-hour primary and secondary ozone ambient air quality standards are met at an ambient air quality monitoring site when the average of the annual fourth-highest daily maximum 8-hour average ozone concentration is less than or equal to 0.08 ppm, as determined in accordance with appendix I to this part.
[62 FR 38894, July 18, 1997]
Effective Date Note:
At 77 FR 30170, May 21, 2012, § 50.10 was amended by adding paragraph (c), effective July 20, 2012. For the convenience of the user, the added text is set forth as follows:
§ 50.10 National 8-hour primary and secondary ambient air quality standards for ozone.
(c) The 1997 ozone NAAQS set forth in paragraph (a) of this section will no longer apply to an area for transportation conformity purposes 1 year after the effective date of the designation of the area for the 2008 ozone NAAQS pursuant to section 107 of the CAA. The 1997 ozone NAAQS set forth in this section will continue to remain applicable to all areas for all other purposes notwithstanding the promulgation of the 2008 ozone NAAQS under § 50.15 or the designation of areas for the 2008 ozone NAAQS. Area designations and classifications with respect to the 1997 ozone NAAQS are codified in 40 CFR part 81.

Title 40 published on 2014-07-01.

The following are only the Rules published in the Federal Register after the published date of Title 40.

For a complete list of all Rules, Proposed Rules, and Notices view the Rulemaking tab.

  • 2015-03-06; vol. 80 # 44 - Friday, March 6, 2015
    1. 80 FR 12264 - Implementation of the 2008 National Ambient Air Quality Standards for Ozone: State Implementation Plan Requirements
      GPO FDSys XML | Text
      ENVIRONMENTAL PROTECTION AGENCY
      Final rule.
      This final rule is effective on April 6, 2015.
      40 CFR Parts 50, 51, 52, 70, and 71

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 2014-07-01

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

  • 2015-04-03; vol. 80 # 64 - Friday, April 3, 2015
    1. 80 FR 18177 - Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements
      GPO FDSys XML | Text
      ENVIRONMENTAL PROTECTION AGENCY
      Notice of public hearing and extension of comment period.
      Public Hearing. The public hearing will be held on April 29, 2015, in Washington, DC Please refer to SUPPLEMENTARY INFORMATION for additional information on the public hearing. Comments . Comments must be received on or before May 29, 2015.
      40 CFR Parts 50, 51, and 93