EPA Asks Court to Overturn Biden-Era Limits on Deadly Soot Pollution

December 02, 2025

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by Rachel Frazin (The Hill) The Trump administration on Monday (November 24, 2025) asked a federal court to overturn a Biden-era rule limiting deadly soot pollution. In a court filing, the Environmental Protection Agency (EPA) argued that the Biden-era rule tightening limits was procedurally flawed and therefore should be vacated.

It said that the Biden administration took a “shortcut,” making the rule stricter “without the rigorous, stepwise process that Congress required.”

“EPA now confesses error and urges this Court to vacate the Rule,” the agency said.

The Biden administration tightened the soot pollution limit to 9 micrograms per cubic meter. The Trump administration’s request would restore a looser standard of 12 micrograms per cubic meter that was first put in place by the Obama administration and upheld by the first Trump administration.

The administration had already indicated that it hoped to overturn the Biden-era rule, putting it on a hit list of regulations earlier this year and proclaiming “the greatest day of deregulation our nation has seen.”

Exposure to soot pollution, also known as fine particulate matter, has been linked to premature deaths, heart attacks and asthma.

The move comes in spite of President Trump’s repeated promises of clean air and his pledge to “Make America Healthy Again.”

When it tightened the standards for soot pollution last year, the Biden administration estimated that it would prevent as many as 4,500 premature deaths in 2032, the first year that states would have been required to meet the standard.

However, it faced fierce opposition from industry figures and Republicans, who argued that the standard would be too difficult to meet and could harm the economy. READ MORE

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Trump’s EPA Abandons Defense of National Soot Standard That Saves Lives (Sierra Club)
EPA to scrap lifesaving soot pollution limit: The move could offer an early test of the Trump administration’s aggressive deregulatory agenda. (E&E News Greenwire)
EPA moves to roll back Biden-era particulate limits, signaling a major shift in clean air policy (Utility Dive)
Trump’s EPA Abandons Defense of National Soot Standard That Saves Lives (Clean Technica)

Excerpt from Sierra Club: The National Ambient Air Quality Standards (NAAQS) for PM2.5 – or the soot standards – are a cornerstone of the Clean Air Act. After over a decade without updates, the EPA followed the advice of independent experts and extensive scientific evidence and strengthened the annual soot standard to better protect public health, reducing the allowable level from 12 to 9 micrograms per cubic meter. Corporations and dozens of state attorneys general sued shortly after, though the rule is projected to result in billions of dollars in health benefits, prevent thousands of premature deaths, and deliver cleaner air to millions of people, particularly those living near highways, factories, and power plants.

In April, a coalition of 100 environmental, public health, and community groups urged EPA Administrator Lee Zeldin to uphold and swiftly implement the 2024 soot standard, warning that any delay would endanger already overburdened communities.

In response, Sierra Club Climate Policy Director Patrick Drupp issued the following statement:

“Lee Zeldin’s continued attacks on clean air are reckless, life-threatening, and a complete betrayal of the EPA’s core mission to protect our communities and our environment. While this administration continues to strip away access to affordable health care, they are simultaneously allowing fossil fuel companies to cut corners and make Americans sicker. We will continue to fight back against Lee Zeldin’s dangerous agenda to bolster fossil fuels and protect Americans from toxic pollutants.” READ MORE

Excerpt from E&E News Greenwire: They urged a three-judge panel of the D.C. Circuit to rule before Feb. 7, when EPA is statutorily required to issue a first round of decisions on what parts of the country are flunking the stricter standard of 9 micrograms per cubic meter of air.

Whether the panel will take that route, however, is very much an open question. “I think they’re going to reject it flat out,” Pat Parenteau, professor emeritus at Vermont Law and Graduate School, said in an interview.

Parenteau noted that a 2001 Supreme Court ruling bars EPA from considering the potential compliance pricetag when setting what are formally known as National Ambient Air Quality Standards for soot and other common pollutants. The Trump administration’s current stance, he added, would also preclude regulators from revisiting those standards outside of a Clean Air Act review cycle even if a “health emergency” were to arise.

The judicial panel, made up of a Biden appointee as well as members named by former President Barack Obama and former President Ronald Reagan, seemed inclined to uphold the 9-micrograms rule during oral arguments held last December on legal challenges brought by Kentucky and almost two dozen other Republican-leaning states.

EPA’s bid to now scrap the stronger limit is likely to face resistance from California and other Democratic-led states also enmeshed in the litigation. At the Trump administration’s request, proceedings have been on hold since February to give EPA’s new leadership time to consider its position.

‘Regulatory reset’

Under the Clean Air Act, particulate matter is one of six pollutants subject to National Ambient Air Quality Standards that EPA is supposed to review every five years in light of the latest scientific research into their effects on human health and the environment.

Over the decades, the reviews — and successive tightening of most of those standards — have been a driver of air quality improvements credited with dramatic public health gains. They’ve also encountered intense opposition from industry advocates who say that the increasingly stricter limits hurt economic growth by making it more difficult to obtain permits for new projects.

Soot is technically known as fine particulate matter or PM2.5 because individual specks or droplets are no bigger than 2.5 microns in diameter or one-thirtieth the width of human hair. Direct and indirect sources include emissions from coal-fired power plants, tailpipe exhaust and wood stoves, meaning that any change to EPA regulations can ripple across wide swaths of the economy.

Because of their tiny size, those particles are able to find their way deep into the lungs and even reach the human bloodstream. Scientists have tied them a litany of heart and lung ailments as well as higher odds of developing Alzehimer’s disease and other neurological disorders.

In opting to cut the standard early last year from 12 micrograms per cubic meter of air to 9 micrograms, EPA predicted the change would prevent up to 4,500 premature deaths in 2032 when it is supposed to be fully in effect.

Because the agency also found that particulate exposure disproportionately harmed people of color, then-Administrator Michael Regan framed the stricter limit as an important step in furthering environmental justice.

In an unprecedented about-face, Regan’s decision also reversed the 2020 finding of EPA leaders during Trump’s first term that the earlier status quo was adequate.

In then revisiting that finding, Regan oversaw what was technically deemed a “reconsideration” of particulate standards instead of a full-fledged review. That truncated process has since fueled objections that the Biden administration failed to follow Clean Air Act requirements.

Even before Trump returned to office this past January, the National Association of Manufacturers and other business lobbies asked his incoming administration to reexamine the particulate rule as part of a broader “regulatory reset.”

In March, EPA Administrator Lee Zeldin included the standard on a lengthy list of Biden-era regulations targeted for rollbacks. In a court filing this summer, air chief Aaron Szabo signaled the administration’s goal of vacating the standard by this coming February in favor of a replacement rule already in development. READ MORE

Excerpt from Utility Dive: The EPA Press Office said in an emailed statement that the rule “was not based on the full analysis of available science that the statute requires” and would cost “hundreds of millions, if not billions of dollars to American citizens if allowed to be implemented.”

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Republican attorneys general from 24 states and a coalition of industry organizations filed lawsuits with the U.S. Court of Appeals for the D.C. Circuit seeking to overturn the new standard in March 2024.

The National Association of Manufacturers said in a press release that complying with the stricter standard “would cost businesses and the U.S. economy huge sums, hampering company operations and job growth and forcing tough choices on states and towns nationwide.”

“This rule will drive jobs and investment out of Kentucky and overseas, leaving employers and hardworking families to pay the price,” Kentucky Attorney General Russell Coleman said in announcing the states’ lawsuit.

Yvonka Hall, executive director of the Northeast Ohio Black Health Coalition, said in a statement Tuesday that Black communities “already carry the burden of polluted air and higher rates of asthma and heart disease.” Weakening the soot standard “will only deepen these disparities and cost more Black lives,” she said.

Studies have found that Black communities are exposed to roughly 1.5 times more soot pollution than the overall population.

In March, as part of the Trump administration’s deregulation push, EPA Administrator Lee Zeldin said the agency would revisit the NAAQS, which he argued had “raised serious concerns from states across the country and served as a major obstacle to permitting.”

A coalition of 100 environmental justice and clean air advocates responded in April with a letter urging the EPA to maintain the stricter standard.

The EPA’s motion to vacate the standard, filed in response to the Republican state attorney generals’ 2024 lawsuit, said there is “no serious possibility” the agency would adopt the stricter soot standard and requested the court grant its motion to vacate it.

“This administration’s EPA has nothing to do with protecting people’s health, saving lives, or serving children, families, or communities,” Patrice Simms, vice president of healthy communities at nonprofit law firm Earthjustice, said in a statement Tuesday. “We will continue to defend this life-saving standard.” READ MORE