CFR›Title 40›Chapter I›Part 58›Subpart F ContainsSection 58.50CorpusDaily eCFRDisplayed edition2026-04-27Last updated2026-04-27 Subpart F—Air Quality Index Reporting Sections 58.50 § 58.50 Index reporting. Previous D Subpart D—Comparability of Ambient Data to the NAAQS Next G Subpart G—Federal Monitoring