Governance & Policy
US Clean Air Act
The principal United States air pollution law, authorising national ambient air quality standards, emission limits for industry and vehicles, and greenhouse gas regulation.
Definition
The Clean Air Act is the primary US federal statute controlling air pollution, first enacted in 1963 and comprehensively revised in 1970 and 1990. It authorises the Environmental Protection Agency to set National Ambient Air Quality Standards, regulate hazardous air pollutants, control vehicle and industrial emissions, run the acid rain trading programme, and — following a 2007 Supreme Court ruling — regulate greenhouse gases as air pollutants.
Quick reference
At a glance
- Subject
- Governance & Policy
- Editorial status
- Editorial draft
- Definition status
- Established
- Last updated
- 19 August 2026
- Also known as
- CAA · Clean Air Act of 1970
Overview
What it means
It is the legal foundation of US air quality management and, in the absence of comprehensive climate legislation, a key tool for federal climate regulation.
How it is used
States write implementation plans; industry holds Title V permits; regulators and litigants contest its use for power-sector carbon rules.
Why it matters
Its standards have delivered large public-health gains, and its scope continues to define how far US climate policy can go without new legislation.
Review
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