C.F.R. » Title 40 » CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY › SUBCHAPTER C—AIR PROGRAMS › PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS

40 C.F.R. § 50.9

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

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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]
Notes of Decisions
Cited in 54 cases (3 in the last 5 years), 1974–2024 · leading case: Whitman v. Am. Trucking Assns., Inc., 531 U.S. 457 (2001).
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Whitman v. Am. Trucking Assns., Inc., 531 U.S. 457 (2001). · cites it 2× “, at 38856 (codified in 40 CFR §§ 50.9 , 50.10 (1999)). American Trucking Associations, Inc.”
State of Texas v. Env't Prot. Agency, 499 F.2d 289 (5th Cir. 1974). · cites it 3× “Since the challenged procedures comply with, and probably are mandated by, the published national standards, 40 C.F.R. 50.9, petitioner's attack is basically directed at those standards.”
BCCA Appeal Grp. v. United States Env't Prot. Agency, 355 F.3d 817 (5th Cir. 2003). “See 40 C.F.R. § 50.9 (a) (promulgating the one-hour ozone standard relevant to the present dispute).”
Ctr. for Cmty. Action v. Faa, 61 F.4th 633 (9th Cir. 2021). “8, 1979) (codified at 40 C.F.R. § 50.9 ). Recognizing that further public health protection was needed, the EPA also adopted an “8-hour ozone standard” that similarly limits average concentrations of ozone.”
Commonwealth of Virginia v. Env't Prot. Agency, State of Connecticut, Intervenors, 108 F.3d 1397 (D.C. Cir. 1997). “40 C.F.R. § 50.9 . If the ambient air exceeds this standard more than once per year averaged over three years, the area is considered in “nonattainment.”
Navistar Int'l Transp. Corp. v. United States Env't Prot. Agency, 941 F.2d 1339 (6th Cir. 1991). “40 C.F.R. § 50.9 (1988); see also id. at pt.”
Kentucky Resources Council, Inc. v. Env't Prot. Agency, 467 F.3d 986 (6th Cir. 2006). “See 40 C.F.R. § 50.9 . The ozone standard was revised in 1997 to a standard of 0.”
South Terminal Corp. v. Env't Prot. Agency, & Russell E. Train, Adm'r, Massachusetts Port Auth. v. Env't Prot. Agency, & Russell E. Train, Adm'r, Sears, Roebuck & Co. v. Env't Prot. Agency, Gulf Oil Corp. v. Env't Prot. Agency, Texaco, Inc. v. Env't Prot. Agency, Fitz-Inn Auto Parks, Inc. v. Env't Prot. Agency, Pilgrim Parking Inc., a Massachusetts Corp. v. Env't Prot. Agency, Marvin A. Meyers, as He is President of Pilgrim Parking Inc., a Massachusetts Corp. v. Env't Prot. Agency, Associated Dry Good Corp. Etc. v. Env't Prot. Agency, 504 F.2d 646 (1st Cir. 1974). · cites it 2× “40 C.F.R. 50.9. Primary and secondary national ambient air quality standards for carbon monoxide are 35 p.”
1000 Friends of Maryland v. Browner, 265 F.3d 216 (4th Cir. 2001). · cites it 2× “2 See 40 C.F.R. § 50.9 (2001). 3 States must establish a state implementation plan (“SIP”) that provides “for implementation, maintenance, and enforcement” of the EPA’s air quality standards.”
Am. Cyanamid Co. v. U.S. Env't Prot. Agency, 810 F.2d 493 (5th Cir. 1987). “To control ozone emissions, Louisiana regulates the storage of Volatile Organic Compounds in “large” tanks, that is, tanks with a capacity of more than 40,000 gallons.”
Louisiana Env't Action Network v. United States Env't Prot. Agency, 382 F.3d 575 (5th Cir. 2004). · cites it 2× “40 C.F.R. § 50.9 . In 1997, the EPA established an eight-hour standard for ozone in accordance with CAA § 109(d), 42 U.”
Brookline v. Comm. of the Dept. of Envtl Quality Eng'g, 439 N.E.2d 792 (Mass. 1982). “We hold that the use of identical limits by the EPA and the DEQE in their ambient air quality standards for ozone ( 40 C.F.R. § 50.9 [1981]; 310 Code Mass. Regs.”
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— 40 C.F.R. § 50.9(b) — 1 case
Amer Trk Assn Inc v. EPA, 195 F.3d 4 (D.C. Cir. 1999).
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