The trajectory · clean air
Clean air: the win that's now plateauing
Not everything on this site points down. The air Americans breathe got dramatically cleaner: average fine-particle pollution, the kind that lodges in lungs and shortens lives, fell by about 45% since 2000, one of the great public-health successes of the era and a credit to both parties' Clean Air Act. But read the recent years honestly: the decline has stalled, wildfire smoke has pushed some years back up, and in 2025 the government moved to abandon the tighter health standard, an attempt a federal appeals court rejected in June 2026. A genuine win, newly contested. On this chart, lower is better.
U.S. average fine-particle pollution (PM2.5, micrograms per cubic meter). ↓ Lower is cleaner air.
Read the plateau correctly, and don't credit one president. The long fall in fine-particle pollution is a real, life-saving win, but the recent flattening is driven mostly by wildfire smoke (a climate signal), not by dirtier factories: the air from regulated industrial sources kept improving even as total exposure stopped falling. The 2025 figure (7.4) edged back up from 2024 (7.1); 2025 was Canada's second-worst fire season, and the plateau continued. PM2.5 is only one pollutant, though the best single proxy for health. The win itself belongs to no single administration: the Clean Air Act of 1970 and its 1990 amendments were bipartisan, and the improvement spans every president since. What is a present-day choice: in February 2024 the health standard was tightened from 12 to 9, and in March 2025 the EPA announced it would reconsider that standard, then asked a court to strike it down. On June 26, 2026 the D.C. Circuit upheld the standard instead, so the limit of 9 stands.