US EPA & Clean Air Act
The cornerstone of American air quality regulation since 1970, now undergoing its most significant rollback in history. Track EPA deregulation, landmark litigation, NAAQS standards, and the widening gap between federal and state enforcement.
The Clean Air Act is the main federal law that controls air pollution in the United States. Passed in 1970 and strengthened in 1990, it gives the Environmental Protection Agency the power to set limits on harmful pollutants -- things like soot, smog-forming chemicals, mercury, and carbon dioxide -- and to require factories, power plants, and vehicles to meet those limits. For more than fifty years, this law has been the reason American air got steadily cleaner.
That trajectory changed sharply in 2025. The Trump administration began rolling back Clean Air Act protections at a pace and scale not seen before. The most consequential action came in February 2026, when the EPA formally rescinded its finding that greenhouse gases endanger public health -- the legal foundation for every federal climate regulation. Without that finding, all federal limits on carbon dioxide emissions from cars, trucks, and power plants have been eliminated.
The federal pullback has created a split between Washington and the states. California and roughly two dozen other states are fighting the rollbacks in court and maintaining their own, stricter air quality programmes. For businesses, this means the regulatory landscape depends heavily on where you operate: companies in states like California, New York, and Washington face rules as strict or stricter than the federal standards that existed a year ago, while companies in states aligned with the federal position face significantly less oversight.
The litigation will take years to resolve, and some rollbacks may ultimately be blocked by the courts. In the meantime, the practical advice for any company subject to air quality regulation is straightforward: understand which states you operate in, track both federal and state rules, and do not assume that reduced federal enforcement means reduced legal risk.
The Trump administration has targeted 31+ environmental rules for rollback. Below are the most significant Clean Air Act actions taken or proposed since January 2025.
From Massachusetts v. EPA to the Endangerment Finding challenge, the Clean Air Act's scope has been shaped as much by courts as by Congress.
The six criteria pollutants regulated under the Clean Air Act. NAAQS form the backbone of air quality regulation -- states must develop plans to meet these standards.
The Clean Air Act operates on cooperative federalism: EPA sets standards, states implement them. As federal enforcement retreats, a patchwork of state responses is emerging.
| DIMENSION | FEDERAL (EPA) | STATE |
|---|---|---|
| Primary authority | EPA under Clean Air Act Sections 113, 120 | State environmental agencies under delegated authority and SIPs |
| Inspection power | EPA can inspect any regulated source; consent decree authority | States conduct ~90% of all inspections under cooperative federalism |
| Penalty authority | Up to $25,000/day/violation (civil); criminal penalties for knowing violations | Varies by state; often matches or exceeds federal penalty levels |
| GHG regulation | Endangerment Finding rescinded (Feb 2026); no new GHG rules expected | California, 16 other states maintain independent GHG programs |
| Vehicle standards | GHG vehicle standards eliminated; traditional pollutant standards remain | California waivers nullified via CRA; litigation pending; Section 177 states affected |
| Citizen suits | Clean Air Act Section 304 allows suits against violators and EPA | Many states have parallel citizen suit provisions |
| Current posture | Deregulatory; 31+ rules targeted for rollback | Aggressive enforcement in blue states; aligned with federal rollbacks in red states |
As federal EPA retreats from Clean Air Act enforcement, states are diverging sharply. Below is a sample of state positions as of April 2026.
How the current regulatory landscape affects different industries under the Clean Air Act.
Despite ongoing rollbacks, the core Clean Air Act permitting and monitoring framework remains in force. These requirements continue to apply.
Select your company type for tailored compliance guidance.