CFR›Title 40›Chapter I›Part 51›Subpart H ContainsSections 51.150–51.153CorpusDaily eCFRDisplayed edition2026-05-18Last updated2026-05-18 Subpart H—Prevention of Air Pollution Emergency Episodes Sections 51.150 § 51.150 Classification of regions for episode plans. 51.151 § 51.151 Significant harm levels. 51.152 § 51.152 Contingency plans. 51.153 § 51.153 Reevaluation of episode plans. Source51 FR 40668, Nov. 7, 1986, unless otherwise noted. Previous G Subpart G—Control Strategy Next J Subpart J—Ambient Air Quality Surveillance