A federal appeals court on Friday rejected the Environmental Protection Agency’s attempt to abandon a Biden-era rule that sets tough standards for deadly soot pollution.

The unanimous ruling by a three-judge panel is a setback for the Trump administration’s deregulatory agenda and its repeated efforts to boost coal, a reliable but polluting energy source.

The decision by the US court of appeals for the District of Columbia circuit leaves intact, for now, a tighter standard set in 2024 on pollution from coal-fired power plants, factories and other industrial sources.

The EPA under Donald Trump asked the appeals court last year to invalidate the Biden-era rule, arguing that the agency under previous leaders had exceeded its statutory authority and acted unreasonably by failing to consider costs to businesses affected by the rule.

The court denied the Trump administration’s request, saying in a decision written by Judge Douglas Ginsburg that the agency’s arguments “lack merit”.

The ruling leaves in place an annual ⁠limit of 9 micrograms of fine particle pollution – often called soot – per cubic meter of air, down from 12 micrograms established more than a decade ago. The EPA rule sets an air quality level that states and counties must achieve in the coming years to reduce particle pollution from power plants, vehicles, industrial sites and wildfires.

The EPA’s bid to walk away from the Biden-era rule came in response to a lawsuit by 25 Republican-led states and a host of business groups that attempted to block the 2024 rule in court. A suit led by attorneys general from Kentucky and West Virginia argued the EPA rule would raise costs for manufacturers, utilities and families and could block new manufacturing plants.

The EPA under Biden had said the tighter limits would prevent more than 800,000 ‌cases ⁠of asthma symptoms, 2,000 hospital visits and 4,500 premature deaths.

An EPA spokesperson said in November that the 2024 rule would cost “hundreds of millions, if not billions of dollars to American citizens” and ​was not based on ​a full ⁠review of available science.

The EPA said on Friday it was reviewing the court decision.

Environmental groups hailed the ruling as a victory for public health and a rebuke of the EPA administrator, Lee Zeldin.

“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,’’ said Patrice Simms, vice-president of healthy communities at Earthjustice, an environmental law firm. “Lee Zeldin’s EPA must stop catering to polluters and must instead fulfill its mission to protect public health,” Simms added.

The ⁠Natural Resources Defense Council (NRDC), another environmental group, said the delay in implementing the 2024 rule has meant millions of Americans continue to breathe unhealthy levels of soot.

“The science has long been clear, and now the law is too. The EPA must stop stalling and deliver the clean air the Clean Air Act requires,’’ said Vijay Limaye, a climate and health scientist for the NRDC.