WASHINGTON — A federal appeals court heard arguments in a challenge to the Trump administration's effort to overturn stricter U.S. limits on fine particulate matter, or soot, with the case centering on whether the Environmental Protection Agency can abandon a 2024 air quality rule adopted under former President Joe Biden. The dispute was argued before the U.S. Court of Appeals for the District of Columbia Circuit, with the court later issuing a unanimous decision rejecting the EPA's request to vacate the rule.
The case is significant because the 2024 rule tightened the national annual standard for fine particulate matter (PM2.5) from 12 micrograms per cubic meter of air to 9 micrograms. The EPA under the Trump administration argued the previous agency leadership exceeded its legal authority and failed to adequately consider regulatory costs, while environmental organizations and several states defended the stricter standard as consistent with the Clean Air Act and public health protections.
The litigation combined challenges brought by industry groups and Republican-led states with the Trump administration's subsequent request that the court invalidate the Biden-era regulation. According to the court's opinion, the EPA changed its litigation position after President Donald Trump returned to office and sought to have the rule vacated rather than defended.
In a decision written by Senior Circuit Judge Douglas Ginsburg, the three-judge panel rejected those arguments. "Because these arguments lack merit, we deny the petitions for review and the motion for vacatur," the opinion said.
The ruling leaves in place the tougher annual PM2.5 standard issued in 2024. The Biden administration had said when adopting the rule that stronger limits on soot pollution would reduce premature deaths, asthma symptoms and hospital visits associated with exposure to fine particulate matter. Opponents, including business groups and Republican-led states, argued the rule would impose substantial compliance costs and affect manufacturing and energy development.
Following the decision, the EPA said it was reviewing the ruling. Environmental organizations welcomed the outcome. Patrice Simms, vice president for healthy communities at Earthjustice, said, "Clean air is not a luxury. The 2024 soot standard is a critical advancement for public health, projected to save thousands of lives every year."
The court's decision leaves the 2024 soot standard in effect while the EPA reviews the ruling. No further court action or agency filing had been officially announced as of Saturday.
