Some 20.3 million people live in the 21 counties where year-round particle pollution levels do not meet the national air quality standard, and that receive a failing grade in “State of the Air” 2022. This is slightly fewer people living in counties with unhealthy levels of year-round particle pollution than in the past three years’ reports, but higher than in reports published in 2017 and 2018.
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 represent recurring exposures over many days and weeks, small differences can have a big impact on public health. The 25 most polluted cities for year-round particle pollution (which actually includes 26 cities this year, because of a tie for 25th place) continued last year’s trend of worsening slightly, by an average of 0.2 micrograms per cubic meter (from 12.0 to 12.2).
Eighteen cities suffered worse year-round levels during 2018-2020 than in last year’s report, and four reported their worst ever: Medford-Grants Pass and Bend-Prineville, Oregon; Redding-Red Bluff, California; and Yakima, Washington. In contrast, six of the most polluted cities had lower year-round levels, including Detroit and Pittsburgh, which reported their lowest levels ever. Pittsburgh, a city long notorious for its industrial pollution, showed the most improvement of any of the cities on this list, lowering its average annual particle pollution level by 1.3 micrograms per cubic meter, and achieving a passing grade for the first time.
New on the worst 25 list this year were Chico, California; Bend-Prineville, Oregon; Yakima, Washington; and Augusta, Georgia. Cleveland, Missoula and New York all improved enough to leave the list.
Unlike the worst 25 cities for the daily measure of particle pollution, the worst 25 cities for long-term particle pollution were more distributed around the country. In addition to cities most affected by western wildfires, cities with high power plant emissions as well as local industrial and mobile sources continued to show up on this list. These included Cincinnati, Indianapolis, Pittsburgh, Detroit, Philadelphia, Chicago, Houston, St. Louis, Augusta and Shreveport.
For year-round average levels of fine particles, all cities but the ten most polluted meet the current national air quality standards and get a passing grade in “State of the Air." However, evidence shows that no threshold exists for harmful effects from particle pollution, even below the official standard. The Lung Association continues to advocate for standards more protective of health for fine particle pollution. See Recommendations for Action.