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Code · CFR · Title 40 — Protection of Environment · Part 50 · § 50.9

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

206 words·~1 min read·/us/cfr/t40/s§ 50.9·

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(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/m 3). 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/m 3) 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]
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§ 50.9
National 1-hour primary and secondary ambient air quality standards for ozone.
Fed. Reg.×303
C.F.R.×5
Cite40 CFR 81
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