Year-Round Particle Pollution Trends

With the recent adoption of a more protective air quality standard for year-round levels of fine particle pollution, “State of the Air” 2024 finds that nearly 90.7 million people are living in 119 counties where year-round particle pollution levels do not meet the national air quality standard, and therefore receive a failing grade. This is a dramatic increase from last year’s report that, using the previous weaker standard, identified slightly fewer than 18.8 million people living in 17 counties with failing marks for year-round levels of fine particle pollution.

cirlce with 65 MM

Nearly 90.7 million people live in counties with failing grades for year-round particle pollution

Most of the additional 71.9 million more people now included in the total population living in areas with failing grades for year-round particle pollution have in fact been breathing unhealthy air for years. The big change this year is the standard, and the overdue recognition of the health risk from year-round exposure to this deadly pollutant. The severity of annual particle pollution only worsened slightly in this year’s report. When looking nationwide at all the counties with measurements for this pollutant, there was little change in the national average of those counties’ year-round levels, with about an equal number improving as got worse. 

Snapshot from the 2004 "State of the Air" report

The “State of the Air” report added grades and ranks for fine particle pollution in 2004, with data from 2001, 2002 and 2003. It was the first time three years of data was available from a new network of monitors put in place following EPA's adoption of a new health standard to address particle pollution in 1997. At that time, 120 counties in 22 states earned an F grade, affecting the health of 66 million people. The air quality standard was weaker than it is now, meaning that in fact many more people were breathing unhealthy air. If the 2024 standard had been in effect at that time, 365 of the monitored counties in 47 states would have gotten failing marks.

By its nature, the year-round measure of average particle pollution is not as volatile as the daily measure. Changes 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. In “State of the Air” 2024, the most polluted cities for year-round particle pollution continued the worsening trend of recent years by an average of about 0.25 micrograms per cubic meter (from 12.3 to 12.55 µg/m3), with 16 metro areas worsening compared with 7 improving. 

Five of the 26 most polluted cities for this measure posted their worst-ever levels of year-round particle pollution. Yakima, Washington remained unchanged from last year’s value, making this the third consecutive year at the same record level.  The other four in the worst-ever group were Sacramento, California; Reno, Nevada; Eugene, Oregon; and Spokane, Washington. Of these four, only Sacramento had also posted a new worst-ever performance in last year’s report. 

In contrast, seven of the 26 most polluted cities had lower year-round levels compared to last year. Three of these tied or exceeded their previous best-ever performance in “State of the Air” 2024: Los Angeles, California; Cincinnati, Ohio and Pittsburgh, Pennsylvania. Nevertheless, all 26 of the worst-ranked metro areas, along with 46 others, had poor enough long-term average particle pollution levels to earn failing grades in this year’s report. 

Twenty of last year’s worst 25 cities remained listed among the 26 (because of a tie for 25th place) in this year’s report. Even though most of their relative ranks shifted by no more than two places, there were some significant changes among the other metro areas. Eugene, Oregon’s increase in its annual average level of fine particle pollution was worst in the country, resulting in its rank dropping from 15th worst in last year’s report to 4th worst in “State of the Air” 2024. In contrast, Birmingham, Alabama’s improvement to its best-ever annual average level of particle pollution was the largest in the country and resulted in its rank improving from 18th to 96th worst. 

Five metro areas improved enough to leave the worst-cities list for this measure. In addition to Birmingham, they were Louisville, Kentucky; Bend, Oregon; and Laredo and McAllen, Texas. Six metro areas replaced them, five of them debuting on the list: Kansas City; Reno, Nevada; Oklahoma City, Oklahoma; Corpus Christi, Texas; and Spokane, Washington. Las Vegas, Nevada rejoined the list for the first time since the 2018 “State of the Air” report.

Unlike the worst 25 cities for the daily measure of particle pollution that were all in the west, the 25 worst cities for annual particle pollution were somewhat more widely distributed around the country. Cities predominantly affected by western drought and wildfires, notably eight in California, and two each in Nevada, Oregon, and Washington, still made up the highest share. However, cities less affected by wildfire smoke in this year’s report, but still grappling with pollution from local industrial and mobile sources, continued to show up on this list. There were ten of these spread among nearly as many states: Indianapolis, Detroit, Houston, Pittsburgh, Kansas City, Cincinnati, Chicago, Augusta, Corpus Christi, and Oklahoma City.


Did You Know?

  1. More than 4 out of 10 people live where the air they breathe earned an F in State of the Air 2020.
  2. 150 million people live in counties that received an F for either ozone or particle pollution in State of the Air 2020.
  3. More than 20.8 million people live in counties that got an F for all three air pollution measures in State of the Air 2020.
  4. Breathing ozone irritates the lungs, resulting in something like a bad sunburn within the lungs.
  5. Breathing in particle pollution can increase the risk of lung cancer, according to the World Health Organization.
  6. Particle pollution can also cause early death and heart attacks, strokes and emergency room visits for people with asthma and cardiovascular disease.
  7. Particles are 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 lower birth weight in newborns.
  9. Do you live near, or work on or near a busy highway? Pollution from the traffic may put you at greater risk of 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 infants, older adults and people with lung diseases like asthma.
  12. People of color and those earning lower incomes are often disproportionately affected by air pollution that put them at higher risk for illnesses.
  13. Air pollution is a serious health threat. It can trigger asthma attacks, harm lung development in children, and can even be deadly.
  14. You can protect your family by checking the air quality forecasts in your community and avoiding exercising or working outdoors when the unhealthy air is expected.
  15. Climate change enhances conditions for ozone to form and makes it harder to keep ozone from forming.
  16. Climate change increases the risk of wildfires that spread particle pollution and ozone in the smoke.
  17. This Administration is trying to roll back or create loopholes in core healthy air protections under the Clean Air Act. The Lung Association opposes these actions that will add pollution to the air we breathe.
  18. Cutting air pollution through the Clean Air Act will prevent at least 230,000 deaths and save $2 trillion annually by 2020.
Get more facts » 
Take Action