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Title 40

Displaying title 40, up to date as of 6/16/2026. Title 40 was last amended 6/15/2026.
There have been changes in the last two weeks to Part 81.
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Title 40Protection of EnvironmentPart / Section
Chapter IEnvironmental Protection Agency1 – 1099
Subchapter CAir Programs50 – 99
Part 81Designation of Areas for Air Quality Planning Purposes81.1 – 81.457
Subpart AMeaning of Terms81.1
§ 81.1Definitions.
Subpart BDesignation of Air Quality Control Regions81.11 – 81.276
Subpart CSection 107 Attainment Status Designations81.300 – 81.356
Subpart DIdentification of Mandatory Class I Federal Areas Where Visibility Is an Important Value81.400 – 81.437
Subpart EIdentification of Interstate Transport Regions81.455 – 81.457
§ 81.455Scope.
§ 81.457Ozone Transport Region.
Appendix A to Part 81
Air Quality Control Regions (AQCR's)