A coalition of 10 states is suing the US Environmental Protection Agency, accusing the agency of unlawfully failing to implement updated national air pollution standards aimed at reducing dangerous soot exposure.
The lawsuit, filed Friday in the US District Court for the Northern District of California, alleges that the EPA missed a statutory deadline under the Clean Air Act to classify areas across the country based on compliance with stricter PM2.5 standards.
The EPA revised its annual PM2.5 standard in February 2024, lowering the allowable concentration from 12 to 9 μg/m³. Under the law, the agency had until 7th February, 2026, to designate regions as ‘attainment,’ ‘nonattainment,’ or ‘unclassifiable’ based on whether they meet the tougher limits.
Nearly three months after that deadline, no designations have been made.
California Attorney General Rob Bonta, whose state is leading the legal challenge, said the EPA’s failure has stalled critical efforts to combat air pollution and protect public health.
‘This is about something simple – the air we breathe,’ Bonta said at a Friday news conference announcing the lawsuit.
Health experts and the EPA have also warned that lower-income communities and communities of color face disproportionate exposure to particulate pollution.
The plaintiffs argue that without formal nonattainment designations, states are deprived of key enforcement tools under the Clean Air Act. Those include the ability to impose stronger pollution controls, challenge polluting activities in federal court, and access federal grants to reduce emissions.
Bonta said the delay also weakens the position of downwind communities, which often bear the impact of pollution generated in neighboring states.
The lawsuit comes as the EPA under Administrator Lee Zeldin has sought to vacate the strengthened PM2.5 standards entirely, asking the D.C. Circuit in late 2025 to throw out the updated rule. That request remains pending, but the plaintiffs argue the standards remain legally in force and must be implemented.
California is joined in the lawsuit by Connecticut, Hawai‘i, Maryland, Massachusetts, Minnesota, New York, Oregon, Vermont, Wisconsin, and the District of Columbia, along with Harris County and New York City.
The coalition is asking the court to order the EPA to issue the overdue designations within 150 days, arguing that every month of delay prolongs preventable health risks and undermines efforts to clean the nation’s air.
Photo: Wolfgang Weiser
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