A federal law designed to control emissions of air pollutants throughout the US with National Ambient Air Quality Standards (NAAQSs) (42 U.S.C. §§ 7401-7661). The CAA creates health-based standards to determine safe pollutant levels and technology-based standards to measure industries' pollution reduction requirements. States must apply the CAA's standards by creating a State Implementation Plan (SIP). An SIP must provide a system for determining whether Environmental Protection Agency standards have been achieved and set up an enforcement program.

For further information see Practice Note, Environmental Law: Overview: Clean Air Act.