A unanimous three-judge D.C. Circuit panel left the 2024 soot standard in place, rejecting the EPA’s request to invalidate the Biden-era rule and calling the agency’s arguments meritless.
The rule cuts the annual fine-particle limit to 9 micrograms per cubic meter from 12, requiring states and counties to meet tighter air-quality targets for pollution from power plants, vehicles, industry and wildfires.
The Trump EPA had sought to abandon the standard amid a lawsuit from 25 Republican-led states and business groups, which argued it would raise costs for manufacturers, utilities and families and hinder new plants.
Biden’s EPA said the tougher limit could prevent more than 800,000 asthma-symptom cases, 2,000 hospital visits and 4,500 premature deaths, while environmental groups urged EPA chief Lee Zeldin to stop delaying enforcement.