US lawFederal (United States)RegulationsTitle 40 CFR — Protection of EnvironmentChapter I — ENVIRONMENTAL PROTECTION AGENCYPart 50 — NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDSAppendix E to Part 5040 C.F.R. Appendix E to Part 50[Reserved]ReservedLast amended: 2016Year: 2026Length: 8 wordsOfficial source Cite as 40 C.F.R. Appendix E to Part 50 (2026)40 C.F.R. Appendix E to Part 50. [Reserved]Previous40 C.F.R. Appendix D to Part 50Next40 C.F.R. Appendix F to Part 50