§ 50.19 National primary and secondary ambient air quality standards for ozone.
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Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
3(a) The level of the national 8-hour primary ambient air quality standard for ozone (O) is 0.070 parts per million (ppm), daily maximum 8-hour average, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter or an equivalent method designated in accordance with part 53 of this chapter.
33(b) The 8-hour primary O ambient air quality standard is met at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average O concentration is less than or equal to 0.070 ppm, as determined in accordance with appendix U to this part.
3(c) The level of the national secondary ambient air quality standard for O is 0.070 ppm, daily maximum 8-hour average, measured by a reference method based on appendix D to this part and designated in accordance with part 53 of this chapter or an equivalent method designated in accordance with part 53 of this chapter.
33(d) The 8-hour secondary O ambient air quality standard is met at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average O concentration is less than or equal to 0.070 ppm, as determined in accordance with appendix U to this part.
[80 FR 65452, Oct. 26, 2015]
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