Court Upholds Life-Saving National Soot Air Quality Standard

Today, the U.S. Court of Appeals for the D.C. Circuit upheld the national, health-based limit on fine particulate matter (PM2.5), also known as soot, that the Environmental Protection Agency (EPA) strengthened in 2024.

Soot, made up of tiny toxic particles that lodge deep in the lungs, results in severe health harms, including premature death, and comes from sources like vehicle exhaust pipes, power plants, and factories.

The National Ambient Air Quality Standards (NAAQS) for PM2.5 set baseline national air quality standards to reduce the harms of this deadly air pollutant for communities across the country. Last year, in an unprecedented move, Trump’s EPA gave up defending the strengthened standard against challenges from industry and aligned states and asked the court to strike it down on narrow legal grounds, without ever disputing the science underlying the standard. Health, environmental, and community groups, along with a coalition of states led by California, continued to defend the standard.

“Clean air is not a luxury. We are thrilled these vital air quality standards have been upheld by a federal court,” said Patrice Simms, vice president of Healthy Communities at Earthjustice. “The 2024 soot standard is a critical advancement for public health, projected to save thousands of lives every year. Lee Zeldin’s EPA must stop catering to polluters and must instead fulfill its mission to protect public health. The time for implementing the 2024 soot standard is now.”

“Fine particulate matter standards provide critical public health protections. The court correctly rejected EPA’s about-face on the need for a stronger standard,” said Shaun Goho, senior director, Legal Advocacy at Clean Air Task Force. “The science is clear that soot has many serious health impacts, particularly for children, the elderly, and those with asthma. By EPA’s own estimate, implementing the 2024 soot standard will prevent 800,000 cases of asthma symptoms, 2,000 hospital visits, and 4,500 premature deaths in 2032. Today marks an important step in the right direction, but EPA must now implement the 2024 standard without delay.”

“The federal court’s decision to uphold the 2024 strengthened particle pollution standard is a win for public health,” said Katie Huffling, DNP, RN, CNM, FAAN, executive director, Alliance of Nurses for Healthy Environments. “Every day in practice, nurses witness and treat conditions made worse by soot pollution. From asthma exacerbations and chronic obstructive pulmonary disease to heart disease and preterm birth, nurses see the real-world health implications of toxic air pollution. The science shows stronger limits to reduce dangerous soot pollution provide significant health benefits for Americans, especially for those most vulnerable and those exposed to higher levels of particulate matter pollution. We now urge EPA to fully implement the strengthened standard to ensure those health benefits are realized.”

“Today’s federal court decision is good news for clean air in America and for the millions of people harmed by deadly soot,” said Noha Haggag, senior attorney for Environmental Defense Fund. “Soot can cause asthma attacks, lung cancer, and premature deaths. The court’s rejection of the Trump administration’s attempt to eliminate our national health standards for soot will mean healthier, longer lives for people across the country.”

“While the Trump EPA has dragged its heels, millions of Americans have kept breathing unhealthy air,” said Vijay Limaye, climate and health scientist at NRDC. Every day of delay means more premature deaths, more asthma attacks, and more hospitalizations. This decision removes any remaining doubt: the science has long been clear, and now the law is too. The Trump EPA must stop stalling and deliver the healthier air the science and the law demand.”

“The court did the right thing today by standing up for our health and safety,” said Rachel Briggs, Conservation Law Foundation staff attorney. “We should never put the polluting status-quo over people, especially when it fuels chronic respiratory and cardiac illnesses. We’ll never compromise when it comes to the safety of our neighbors, communities, and the low-income and Black and Brown families that continue to shoulder the worst of these toxins.”

Background

Soot is a lethal combination of metals, organic chemicals, and acidic substances so tiny that they can be easily inhaled into our lungs and delivered directly into our bloodstream. It threatens our health and environment — posing especially heightened risks for children, seniors and people with chronic illnesses. Among the health harms it is linked to are death, cardiovascular harms, new and exacerbated asthma cases, lung cancer, and serious neurological harms, like Alzheimer’s disease.

Under the Clean Air Act, the EPA has for decades set baseline national air quality standards for six harmful pollutants, including soot. In 2024 the agency strengthened the soot standard from 12 to 9 micrograms per cubic meter,

According to the EPA, the strengthened soot standard will result in significant public health net benefits that could be as high as $46 billion by 2032. The EPA’s estimate of costs is an order of magnitude less. Polluters’ exaggerated claims about costs have been repeatedly debunked.

After the agency strengthened the soot standard, corporations and attorneys general in allied states sued. Earthjustice, its clients and partners intervened to defend the strengthened soot standard. Earthjustice clients are Alliance of Nurses for Healthy Environments, American Lung Association, Environmental Defense Fund, NRDC (Natural Resources Defense Council), Northeast Ohio Community Resilience Centre (formerly the Northeast Ohio Black Health Coalition), Rio Grande International Study Center, and Sierra Club. Clean Air Task Force represents Citizens for Pennsylvania’s Future and Conservation Law Foundation.

A recent white paper found that 75 million people live in counties whose air quality violates the standard. The Clean Air Act mandated that the EPA formally identify the areas that violate the standard by Feb. 6, 2026. When EPA failed to meet that deadline, a group of health, environmental, and community groups, and a state coalition, sued to require it to obey the law. That key step will require pollution reductions in those areas, to bring them into compliance with the 2024 NAAQS.