Year-Round Particle Pollution Trends

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“State of the Air” 2026 finds that 75.9 million people living in 84 counties across 21 states have been exposed to year-round levels of particle pollution that do not meet the annual air quality standard. This is 9.1 million fewer than last year, but it is the third highest number in the history of the report, and a sobering reminder of the widespread, chronic nature of this deadly form of air pollution.

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76 million people live in counties with failing grades for year-round particle pollution

When looking nationwide at all the counties with measurements for annual particle pollution, the average severity of this pollutant reached its lowest value in the history of the “State of the Air” report. However, there were 52 metro areas across the country whose worst county earned a failing grade. By its nature, the year-round measure of average particle pollution is not as changeable from year to year as the daily measure. Variations over time may look smaller, but because they typically represent recurring exposures over many days and weeks, seemingly minor differences can have a big impact on public health.

Annual particle pollution levels are most often highest in places that are subject to multiple sources of emissions all year long, such as from highways, oil and gas extraction, power generation and industry. The additional pollution load from wildfire smoke, though comparatively short-lived in any one location, can strongly influence that location’s annual average. In this year’s report, this influence can be found reflected in geographic shifts similar to those seen with short-term particle pollution.

Compared with last year’s report, the year-round average concentration of fine particle pollution generally improved in much of the United States, with about three-quarters of results showing improvement. In fact, increases in statewide annual particle pollution average values were observed in only six states—the greatest in Texas (also the state with the worst overall average) and Wyoming (which still has a low statewide average; only Hawaii’s is lower), but also in Arkansas, Louisiana, Mississippi and South Carolina.

In contrast, the states that saw the strongest improvement in year-round particle pollution compared to last year’s report were mainly in the eastern half of the country. Sixteen states, plus the District of Columbia and Puerto Rico, saw their year-round averages for particle pollution improve in every one of their counties graded for this measure. Five other states posted results that were either the same or better than last year’s in every county whose performance could be compared. Nineteen more states improved in the majority of their counties even as at least one of their counties worsened.

In “State of the Air” 2026, of the worst 26 metropolitan areas for year-round particle pollution (26 because there was a four-way tie for 23rd place), 15 improved, 10 worsened and one stayed the same compared to last year’s report. Of those that worsened, only one, Brownsville-Harlingen-Raymondville, Texas, reported a new worst-ever value, falling from 16th worst in last year’s report to second worst in the nation. In contrast, of those that improved, seven reported new best-ever values for their worst counties: Fresno-Hanford-Corcoran, California and Los Angeles-Long Beach, California posted improvements (though still posting failing grades) and for a second year in a row, both recorded their lowest year-round averages of high particle pollution in the history of this report. In addition, Bakersfield-Delano, California, Cincinnati-Wilmington, OH-KY-IN, Pittsburgh-Weirton-Steubenville, PA-OH-WV, San Jose-San Francisco-Oakland, California, and Visalia, California, all newly posted their best-ever results. 

Though fifteen rankings on this list remained relatively stable, changing at most only three places compared with last year’s report, four changed more than ten places from their former position. The biggest change among the Worst 25 was San Diego-Chula Vista-Carlsbad, California’s leap from 59th worst in last year’s report to 5th worst; the other three were all in Texas: Austin-Round Rock-San Marcos, Texas (39th to 23rd), Brownsville-Harlingen-Raymondville, Texas (16th to 2nd), and McAllen-Edinburg, Texas (39th to 17th). 

In addition to three of the four above cities having been added to the Worst 25 list for year-round particle pollution, three others were similarly newly listed: Dallas-Fort Worth, Texas-Oklahoma (30th to 22nd); Little Rock-North Little Rock, Arkansas-Texas (26th to 17th); and Philadelphia-Reading-Camden, PA-NJ-DE-MD (also 26th to 17th).

Again, these changes meant that five metro areas improved enough to leave the Worst 25 list. Two improved but still have failing grades: Missoula, Montana, and St. Louis-St. Charles-Farmington, Missouri-Illinois. Three others had been failing, but now pass: Sacramento-Roseville, California; Spokane-Spokane Valley-Coeur d'Alene, Washington-Idaho; and Yakima, Washington.

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The geographical distribution of cities on the Worst 25 list for year-round fine particle pollution is more widespread than in previous years in some respects. Though California retains its position of being the state with the most metro areas on the list with seven of the 26 most-polluted cities, the other western states are limited to Oregon with two; then Alaska and Arizona, each with one. In the center of the country, Texas increases to six and Arkansas to one. Then, moving eastward, Illinois and Indiana each with one; finally, Michigan, Ohio and Pennsylvania each with two.

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Did You Know?

  1. Nearly half of the people in the U.S. live where the air they breathe earned an F in “State of the Air” 2025.
  2. More than 156 million people live in counties that received an F for either ozone or particle pollution in “State of the Air” 2025.
  3. More than 42 million people live in counties that got an F for all three air pollution measures in “State of the Air” 2025.
  4. Breathing ozone irritates the lungs, resulting in inflammation—as if your lungs had a bad sunburn.
  5. Breathing in particle pollution can increase the risk of lung cancer.
  6. Particle pollution can cause early death and heart attacks, strokes, and emergency room visits.
  7. Particles in air pollution can be smaller than 1/30th the diameter of a human hair. When you inhale them, they are small enough to get past the body's natural defenses.
  8. Ozone and particle pollution are both linked to increased risk of premature birth and lower birth weight in newborns.
  9. If you live or work near a busy highway, traffic pollution may put you at greater risk of health harm.
  10. People who work or exercise outside face increased risk from the effects of air pollution.
  11. Millions of people are especially vulnerable to the effects of air pollution, including children, older adults, and people with lung diseases such as asthma and COPD.
  12. People of color and people with lower incomes are disproportionately affected by air pollution that puts them at higher risk for illness.
  13. Air pollution is a serious health threat. It can trigger asthma attacks, harm lung development in children, and even be deadly.
  14. You can protect yourself by checking the air quality forecast in your community and avoiding exercising or working outdoors when unhealthy air is expected.
  15. Climate change enhances conditions for ozone pollution to form and makes it harder to clean up communities where ozone levels are high.
  16. Climate change increases the risk for wildfires and resulting smoke that spreads dangerous particle pollution.
  17. Policymakers at every level of government must take steps to clean the air their constituents breathe.
  18. The nation has the Clean Air Act to thank for decades of improvements in air quality. This landmark law has successfully driven pollution reduction for over 50 years.
  19. The U.S. Environmental Protection Agency is critical for cleaning up air pollution. EPA’s staff ensure that air pollution is monitored, write sound rules to clean it up, and make sure those rules are enforced.
  20. The U.S. Environmental Protection Agency is under threat. Despite EPA’s lifesaving role in protecting people’s health from air pollution, big staffing and funding cuts are endangering their work.
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