Regulations last checked for updates: Jan 18, 2025

Title 40 - Protection of Environment last revised: Dec 30, 2025
All TitlesTitle 40Chapter IPart 50 - PART 50—NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS
View all text of Part 50 [§ 50.1 - § 50.21]
§ 50.21 - xxx
Link to an amendment published at 89 FR 105785, Dec. 27, 2024.
authority: 42 U.S.C. 7401,
source: 36 FR 22384, Nov. 25, 1971, unless otherwise noted.
cite as: 40 CFR 50.21
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