About GPO   |   Newsroom/Media   |   Congressional Relations   |   Inspector General   |   Careers   |   Contact   |   askGPO   |   Help  
 
Home   |   Customers   |   Vendors   |   Libraries  

The Electronic Code of Federal Regulations (e-CFR) is a regularly updated, unofficial editorial compilation of CFR material and Federal Register amendments produced by the National Archives and Records Administration's Office of the Federal Register (OFR) and the Government Printing Office.

Parallel Table of Authorities and Rules for the Code of Federal Regulations and the United States Code
Text | PDF

Find, review, and submit comments on Federal rules that are open for comment and published in the Federal Register using Regulations.gov.

Purchase individual CFR titles from the U.S. Government Online Bookstore.

Find issues of the CFR (including issues prior to 1996) at a local Federal depository library.

[1]
 
 

Electronic Code of Federal Regulations

e-CFR Data is current as of October 30, 2014

Title 40Chapter ISubchapter CPart 50 → §50.9


Title 40: Protection of Environment
PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS


§50.9   National 1-hour primary and secondary ambient air quality standards for ozone.

(a) The level of the national 1-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 0.12 parts per million (235 µg/m3). The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 parts per million (235 µg/m3) is equal to or less than 1, as determined by appendix H to this part.

(b) The 1-hour standards set forth in this section will remain applicable to all areas notwithstanding the promulgation of 8-hour ozone standards under §50.10. The 1-hour NAAQS set forth in paragraph (a) of this section will no longer apply to an area one year after the effective date of the designation of that area for the 8-hour ozone NAAQS pursuant to section 107 of the Clean Air Act. Area designations and classifications with respect to the 1-hour standards are codified in 40 CFR part 81.

[62 FR 38894, July 18, 1997, as amended at 65 FR 45200, July 20, 2000; 68 FR 38163, June 26, 2003, 69 FR 23996, Apr. 30, 2004; 77 FR 28441, May 14, 2012]



For questions or comments regarding e-CFR editorial content, features, or design, email ecfr@nara.gov.
For questions concerning e-CFR programming and delivery issues, email webteam@gpo.gov.