More Than 71 Million People Still Breathe Unhealthy Air as EPA Delays Soot Protections

Since we published our blog post and white paper concerning the Environmental Protection Agency’s (EPA) failure to implement the 2024 particulate matter, also referred to as PM2.5 or soot, National Ambient Air Quality Standard (NAAQS), there have been several updates.

As anticipated, the EPA missed its February 2026 deadline to issue designations. Those designations identify as “nonattainment” the areas that violate the 2024 standard and as “attainment” the areas that comply with the standard, and are a key step in bringing communities around the country into compliance with the standard. In response, we sued on behalf of our clients to compel EPA to act. While that case was working its way through the court, the D.C. Circuit, in a separate proceeding, upheld the 2024 soot standard. Not long after, the Northern District of California court ruled overwhelmingly in our favor that the EPA is overdue in its duties and gave the agency until Feb. 6, 2027, to issue final designations. Areas in nonattainment will then need to follow concrete steps to bring PM2.5 pollution down.

Then, in October 2026, the EPA doubled down on its stance that these life-saving measures should not move forward and announced it would be completing additional analysis for states, tribes, and territories before making the final court-ordered designations. The EPA opened a comment period on the designations, which runs through Nov. 5, 2026. It is vital that the EPA follow the Clean Air Act and designate as nonattainment the areas that violate the 2024 soot standard, including those nearby areas that contribute to violations, just as it historically has done and said it intended to do in February 2024. Anything else would be illegal and arbitrary.

Most states — 45 out of 50, plus Washington, D.C., Puerto Rico, the Virgin Islands, and three tribes — took the opportunity last year to inform the EPA how the state thinks its areas should be designated. EPA is not required to adhere to the states’ recommendations, but if it intends to deviate from one, it must notify the state at least 120 days before making final designations to give the state an opportunity to disagree with the agency’s decision. Such letters notifying states of the EPA’s planned changes are known as 120-day letters and were due by Oct. 9, 2026, under the deadline set by the Northern District of California ruling. As noted above, the EPA publicly released the letters on Oct. 2.

In the midst of those events, on June 9, the EPA released additional data that incorporated air monitoring done in 2025. These data are referred to as the 2025 PM2.5 design values (DVs) and consist of the three-year averages of annual ambient PM2.5 concentrations at monitors across the country from 2023 through 2025. Then, on Sept. 16, EPA re-released the same design values with a few changes incorporating the agency’s approvals of several exceptional event demonstrations, which moved some counties from nonattainment to attainment. The 2025 DVs are important because they are what the EPA will rely on in the now ongoing designations process. We accordingly updated the analysis in our original blog post and white paper with these new data to determine how many people live in counties with air violating the standard of 9.0 µg/m³. The most current information confirms that soot pollution remains a serious concern for tens of millions of people across the country.

The 2025 PM2.5 design values show 68 counties across 20 states (Alabama, Alaska, Arizona, Arkansas, California, Georgia, Illinois, Indiana, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, New Mexico, Ohio, Oklahoma, Pennsylvania, and Texas)^[1] reporting a design value greater than the 9.0 µ/m³ standard. The total population of counties not meeting the standard, distributed over 52 metro areas, is over 71 million.^[2] DuPage (930,000 people) and Will (701,000 people) in Illinois; Dakota, Minnesota (446,000 people); and Stark, Ohio (374,000 people) are among the counties that previously met the standard, but no longer do.^[3] These counties join other areas with long-standing PM2.5 pollution problems on the list of counties where monitoring shows unhealthy air.

Counties violating PM2.5 standard (2025 DVs)
Number of counties	68
Population	71,682,747

The subset of U.S. counties with 2025 DVs violating the standard is home to far more people of color, percentage-wise, than the U.S as a whole: counties with unhealthy air are 56% people of color, compared with 39% nationwide.^[4] This subset of counties is also 15% Black and 35% Hispanic/Latino, whereas the U.S. overall is 12.5% Black and 20% Hispanic/Latino, making PM2.5 pollution a problem of health inequity.^[5]

Now that the EPA has requested additional information from states, tribes and territories, it’s unclear how the agency will use the 2025 design values to set the designations. According to the EPA’s own analysis, implementing the updated soot standard could prevent up to 4,500 premature deaths each year, reduce hundreds of thousands of asthma cases, and deliver up to $46 billion in net benefits. Hopefully communities soon will see meaningful relief if the EPA abides by the law and rightfully implements the court-ordered designations and upholds the life-saving national soot standard.

Sources

[1] In contrast to the 2024 DVs, Minnesota, New Mexico, and Oklahoma now have one county each with a 2025 DV above the standard; and Idaho, Tennessee, and Washington no longer have any counties with a 2025 DV above the standard.

[2] See 2025 Design Value Reports – PM2.5 Design Values, 2025 (xlsx), available at https://www.epa.gov/air-trends/air-quality-design-values#report.

[3] Demographic data obtained from the United States Census Bureau, American Community Survey 5-Year Data (2009-2024) (Jan. 29, 2026), available at https://www.census.gov/data/developers/data-sets/acs-5year.html.

[4] People of color totals found by subtracting numbers of non-Hispanic white people from the total population of a given area.

[5] Demographic data obtained from the United States Census Bureau, American Community Survey 5-Year Data (2009-2024) (Jan. 29, 2026), available at https://www.census.gov/data/developers/data-sets/acs-5year.html.