2 Oregon towns have some of the dirtiest air in the U.S., new report finds

(NEXSTAR) -- No matter where you live in the U.S., it's probably important to you that the air you breathe is clean and safe. But it's not as simple as looking up in the sky and seeing "clean air," so how can you really know?

That's where the American Lung Association comes in. The organization releases an annual State of the Air report showcasing the country's cleanest and most polluted cities based on year-round particle pollution in the air.

According to the American Lung Association, particle pollution is a mixture of tiny bits of solids and liquids in the air we breathe. Generally, it can come from factories, power plants, and diesel and gasoline-powered vehicles. It can also come from wildfires, wood stoves, or fireplaces.

Most particles are too small to be visible, but when pollution levels are high enough, they can make the air appear thick and hazy.

Exposure to high levels of these particles can result in illness, hospitalization, and premature death. The American Lung Association states that these particles are responsible for nearly 48,000 premature deaths in the United States every year.

In the latest State of the Air report, the American Lung Association looked at the year-round particle pollution in each city from 2020-2022 and determined if a city passed or failed based on whether its average particle pollution was above or below 9 µg/m3, or 9 micrograms of pollution per cubic meter. 9 µg/m3 is considered the baseline by the National Ambient Air Quality Standards (NAAQS).

Landing at the top of the list of most polluted cities is Bakersfield, California, which more than doubled the NAAQS baseline with an average annual particle pollution of 18.8 µg/m3.

California in general did not fare too well, with six cities landing in the top ten most polluted. Three fellow western states filled out the rest of the top ten. Oregon had two cities in the top ten, and Arizona and Alaska each had one.

Here's the full list of the top ten most polluted cities, according to the 2024 State of the Air report:

1. Bakersfield, CA - 18.8 µg/m3
2. Visalia, CA - 18.4 µg/m3
3. Fresno-Madera-Hanford, CA - 17.5 µg/m3
4. Eugene-Springfield, OR - 14.7 µg/m3
5. San Jose-San Francisco-Oakland, CA - 14.3 µg/m3
6. Los Angeles-Long Beach, CA - 14 µg/m3
7. Sacramento-Roseville, CA - 13.8 µg/m3
8. Medford-Grants Pass, OR - 13.5 µg/m3
9. Phoenix-Mes, AZ - 12.4 µg/m3
10. Fairbanks, AK - 12.2 µg/m3

Other major cities that were just outside the top ten include Indianapolis, Detroit, Las Vegas, Kansas City, and Chicago.

As for the other side of the spectrum, various areas of the western U.S. were also considered the cleanest cities in the country. Honolulu, Hawaii, finished as the cleanest city in the U.S. with only an average annual particle pollution of 3.7 µg/m3. Hawaii also had another area – Maui's Lahaina metro area – finish not far behind at No. 3. Since this report looked at 2020-2022, the 2023 Lahaina fires were not taken into account. Casper, Wyoming, finished sandwiched between them at No. 2.

Also, only two East Coast cities made the top ten with Wilmington, North Carolina, coming in at No. 4 and Bangor, Maine, at No. 5. Check out the rest of the list of cleanest cities:

1. Honolulu, HI - 3.7 µg/m3
2. Casper, WY - 3.8 µg/m3
3. Kahului-Wailuku-Lahaina, HI - 4.0 µg/m3
4. Wilmington, NC - 4.4 µg/m3
5. Bangor, ME - 4.5 µg/m3
6. Cheyenne, WY - 4.9 µg/m3
7. Duluth, MN-WI - 5.1 µg/m3
8. Colorado Springs, CO - 5.5 µg/m3
9. Anchorage, AK - 5.6 µg/m3
10. St. George, UT - 5.6 µg/m3

As for how the U.S. compares to the rest of the world, last year IQAir ranked the U.S. as the 102nd most polluted country with an average annual particle pollution of 9.1 µg/m3. For perspective, Bangladesh, finished as the most polluted country with 79.9 µg/m3.