Pollution is a major problem worldwide. 39% of the United States population, or around 131.2 million people, live in cities with dirty air, according to the American Lung Association. The EPA reduced the allowable limit of air pollution ratings in February this year to help tackle the issue of pollution in American cities. The cities with the cleanest air are Bangor, Maine, Johnson-City-Kingsport-Bristol, TN-VA, Lincoln-Beatrice, Nebraska, Urban Honolulu, Hawai’i, and Wilmington, North Carolina. As far as cities with the dirtiest air, the answer to that question is a little more technical. There are two types of air pollution that you can experience in urban areas.
The first type is particulate pollution (PM2.5), which comes from wildfires, wood-burning stoves, coal-fired power plants, diesel engines, and other sources of particles. These particles in the air can trigger asthma attacks, heart attacks, strokes, and cause lung cancer. We split particulate pollution into two categories: short-term 24-hour pollution ratings and year-round ratings. More than 90.7 million people live in a county where year-round particle pollution is worse than the national air quality limit.
The second type of air pollution is ozone pollution. This phenomenon occurs when the ozone levels at our breathing altitude are too high. Ozone is a respiratory irritant and its effects on your body are like a sunburn for your lungs. Inhaling ozone can cause shortness of breath, coughing, and asthma attacks, and could even shorten your overall lifespan.
We took our findings from the American Lung Association’s State of the Air report from 2024, which covers the testing that took place over the years of 2020 and 2022. Findings for 2023-2024 regarding cities with the dirtiest air were not yet published at the time of this article’s writing. (Also See Cities Where Summer Is Getting Hotter)
1. Los Angeles–Long Beach California (Highest Ozone)
According to the American Lung Association’s State of the Air 2024 report, the metropolitan area that ranked highest in ozone pollution between 2020 and 2022 was Los Angeles–Long Beach in California. This district ranked number 1 for the most high ozone days out of 228 metropolitan areas.
It also ranked 11th worst for 24-hour particle pollution and 6th worst for annual particle pollution. The Los Angeles–Long Beach area had 175.2 high ozone days between 2020 and 2022. However, in 2023-2024 so far the area has had around 55 fewer high ozone days than they did in 2020–2022. In terms of 24-hour particle pollution, Los Angeles-Long Beach had 20.7 high particle days in the testing period. Its annual particulate pollution concentration level was around 14 µg/m^3.
2. Bakersfield, CA (Year-Round and 24-Hour Pollution)
From the American Lung Association’s 2022–2024 State of the Air research, the metropolitan area with the worst year-round particle pollution concentration is also the city with the worst 24-hour particle pollution, which makes sense as these statistics are intrinsically tied together. Bakersfield, CA ranked number 3 worst in the country for high ozone days out of 228 metropolitan areas surveyed.
It ranked number 1 worst in both 24-hour particle pollution (ranked out of 223 metropolitan areas) and annual particle pollution concentration out of 204 metropolitan areas. The area had 87.5 high ozone days and 61.8 high particle days between 2020 and 2022. Its annual particle pollution concentration was 18.8 µg/m^3, the highest in the country.
3. Visalia, CA
The American Lung Association’s 2024 State of the Air report, which covers the years 2020–2022, states that the municipality of Visalia, California came in behind Los Angeles-Long Beach and Bakersfield. It ranked number 2 worst for high ozone days out of the 228 metropolitan areas surveyed.
It also ranked number 5 worst for 24-hour particle pollution out of 223 metropolitan areas surveyed. Additionally, it came in number 2 worst for annual particle pollution out of 204 areas. The area had 103 high ozone days between the years of 2020 and 2022. It also had 35.3 high particle days and an annual particulate pollution concentration of 18.4 µg/m^3.
4. Fresno-Madera-Hanford, CA
The fourth worst city to live in for air pollution according to the American Lung Association’s 2024 State of the Air report was the Fresno-Madera-Hanford metropolitan area in California. This municipality ranked number 4 worst for high ozone days out of the 228 metropolitan areas surveyed.
It also ranked number 2 worst for 24-hour particle pollution and number 3 worst in the nation for annual particulate pollution concentration out of 204 participating metropolitan areas. Between the years 2020 and 2022, the Fresno-Madera-Hanford area saw 52.2 high ozone days. In the same span, they had 54.8 high particle days and an annual particulate pollution concentration of 17.5 µg/m^3.
5. Eugene-Springfield, OR
Looking at the American Lung Association’s 2024 State of the Air report, the fifth worst city for air pollution nationwide was the Eugene-Springfield area in Oregon. The metropolitan area ranked number 116 worst for high ozone concentration days, though this is just below the half-point as there were 228 metropolitan areas included in the report for this metric.
However, it ranked number 4 worst for 24-hour particulate pollution levels and number 4 worst for annual particulate pollution concentration. It had 0.3 high ozone days between the years of 2020 and 2022. During that time, however, it had 38.5 high particle days and an annual particulate pollution concentration of 14.7 µg/m^3.
6. Fairbanks, AK
Moving off the West Coast, the sixth worst city to live in for dirty air is Fairbanks, Arkansas. However, its statistics might be confusing. Fairbanks actually tied for number one in the best for high ozone pollution days, with zero high ozone days at all during the testing period, tied with other cities with no major issue with ozone pollution.
However, it ranked number 3 worst for 24-hour particulate pollution for the 2020–2022 testing period. During the testing period, the city of Fairbanks, AK had 38.8 high particle days. It also ranked number 10 worst for annual particle pollution, with an annual concentration average of 14.7 µg/m^3 between 2020 and 2022.
7. Phoenix–Mesa, AZ
Moving right along down to the desert, we have the seventh worst of the cities with the dirtiest air in America, the Phoenix-Mesa area in Arizona. This metropolitan area ranked number 5 worst for high ozone pollution days out of the 228 areas surveyed. It also ranked number 16 worst out of 223 for 24-hour particle pollution and number 9 worst for annual particle pollution concentration out of 204 areas.
Between the years 2020 and 2022, the Phoenix-Mesa area had 19.7 high ozone days. They also suffered from 24.2 high particle pollution days and had an average annual particle pollution concentration of 14.3 µg/m^3, the fifth worst in the nation.
8. San Jose–San Fransisco–Oakland, CA
Moving back to California (because it’s always California, isn’t it?), we have the San Jose–San Fransisco–Oakland area coming in around eighth worst in the nation for air pollution. It ranked 12 worst for high ozone days out of 228 metropolitan areas surveyed.
The area also ranked 7 worst for 24-hour particle pollution out of 223 areas and number 5 worst for annual particle pollution concentration out of 204 areas. Throughout the 2020–2022 study, the San Jose–San Fransisco–Oaklad area had 19.7 high ozone days. It also had 24.2 high particle days and an annual particle pollution concentration of 14.3 µg/m^3 during the testing period.
9. Denver-Aurora, CO
Once again moving out of California, we have the Denver-Aurora area in Colorado coming in at a rough ninth place for the worst air in America. Denver-Aurora ranked 19th worst out of 223 metropolitan areas for high ozone pollution days. The area had 12.7 high ozone days during the 2020–2022 testing period.
It also ranked 6th worst for 24-hour particle pollution, with 26.8 high particle pollution days during the testing period. Finally, this area ranked number 18 worst out of 204 metropolitan areas in annual particle pollution concentration, with an average concentration of 9.3 µg/m^3.
10. Reno–Carson City–Fernley, NV
Coming in tenth on the list is the Reno–Carson City–Fernley area of Nevada. This metropolitan area ranked number 19 worst out of 228 total surveyed areas for high ozone pollution days. However, its particulate pollution was even worse. It ranked number 6 worst for 24-hour particle pollution levels and number 18 worst for annual particle pollution concentration averages.
These ratings are out of 223 and 204 metropolitan areas respectively. During the 2020–2022 testing period, Reno–Carson City–Fernley had 12.7 high ozone days, 22 high particle pollution days, and an average particulate pollution concentration of 10 µg/m^3 yearly.
11. Sacramento–Roseville, CA
We are once again back in California. It really does seem like California is home to most of the cities with the dirtiest air in America. Sacramento-Roseville was the 11th worst metropolitan area to live in for air pollution ratings in America. This area ranked number 7 worst for high ozone days out of 228 surveyed metros.
It also ranked number 9 worst for 24-hour particle pollution and 7 worst for annual particle pollution. Throughout the 2020–2022 testing period, Sacramento–Roseville had 29.3 high ozone days. During this time, they also experienced 10 high particle pollution days and an average annual particle pollution concentration of 13.8 µg/m^3.
12. San Diego–Chula Vista–Carlsbad, CA
Another California metro area in the running. The San Diego–Chula Vista–Carlsbad metropolitan area in California ranked 12th worst in the nation for air quality. It came in 8th place worst for high ozone days out of the 228 metros surveyed. Additionally, this area came in 18th worst for 24-hour particle pollution and 33rd worst for annual particulate pollution concentrations out of 223 and 204 metro areas respectively. During the 2020–2022 testing period, the area experienced 25.2 high ozone days, and 10 high particulate pollution days, and had an average particulate pollution concentration of 10 µg/m^3 yearly.
13. Medford–Grants Pass, OR
Moving a bit north of California, we have another Oregon metro area. The Medford–Grants Pass, Oregon area was the thirteenth worst city in America for air quality during the 2020–2022 testing period by the American Lung Association. It ranked number 79 worst for high ozone days out of 228 metropolitan areas. This area also ranked number 29 worst out of 223 metro areas for 24-hour particulate pollution concentrations, and number 8 worst for annual particulate pollution concentration out of 204 metro areas. The area had 1 high ozone day between 2020 and 2022. For high particulate pollution concentration days, Medford–Grants Pass experienced 6.8 during the testing period. Its annual particle pollution concentration was 13.5 µg/m^3 from 2020 until 2022.
14. Redding–Red Bluff, CA
Sticking with the West Coast we have the 14th worst place to live in America if air quality is important to you, the Redding–Red Bluff area in California. This area ranked number 22 worst for high ozone days out of 228 surveyed metro areas. For 24-hour particulate pollution, Redding–Red Bluff comes in 8th out of 223 metro areas. Its annual particle pollution concentration was the 37th worst in the country.
During the 2020–2022 testing period, the Redding–Red Bluff area experienced 11.5 high ozone days. In the same period, it had 23.7 high particulate pollution days and an annual particulate pollution average concentration of 9.9 µg/m^3.
15. Salt Lake City–Provo–Orem, UT
Moving back over into the deserts of Utah, we have the Salt Lake City–Provo–Orem area, which is one of the worst places in America for air quality. The metro area ranked 9th worst for ozone pollution out of 228 metropolitan areas surveyed.
For 24-hour particle pollution, Salt Lake City–Provo–Orem ranked 19th worst out of the 223 areas tested. Out of the 204 areas tested for annual particulate pollution, it ranked 37 worst. During the 2020–2022 testing period, the area experienced 24 high ozone days, and 9.8 high particle days, and had an annual particle pollution concentration average of 9.9 µg/m^3.
16. Houston–The Woodlands, TX
Moving into the central United States, we have the Houston–The Woodlands area in Texas. The Houston–The Woodlands area ranked 16th out of the cities with the dirtiest air in America. This area ranked 10th worst in the nation for high ozone concentration days. In the area of high particle pollution per 24 hours, the area ranked 60th worst in the nation.
In terms of annual particulate pollution concentration, the Houston–The Woodlands metro area is the 16th worst in the nation. During the 2020–2022 testing period for the State of the Air, the Houston–The Woodlands area had 23.2 high ozone days, 1.8 high particle days, and an annual particle pollution concentration average of 11.4 µg/m^3.
17. Indianapolis–Carmel–Muncie, IN
Out in the Midwest, air quality isn’t all sunshine and rainbows either. They also have some of the cities with the dirtiest air in America. The Indianapolis–Carmel–Muncie area of Indiana was the 17th worst area in the nation for air quality. It ranked number 60 worst in the nation for high ozone days, number 10 worst for 24-hour particulate pollution and 11 worst for annual particle pollution concentrations.
During the American Lung Association’s three-year testing period between 2020 and 2022, the Indianapolis–Carmel–Muncie area had 2 high ozone days after weighting. For high particle days, the area experienced 6.5 of these days. Its annual particle pollution concentration average was 11.9 µg/m^3.
18. Chico, CA
California is back on the list again. This time we’re looking at Chico, California, which ranked 18th worst in the nation for poor air quality overall. It had the 26th highest number of high ozone days out of the 228 metro areas surveyed.
The area also ranked 10th worst for 24-hour particle pollution concentrations and had the 14th worst annual particle pollution concentration average in the nation. Chico had 6.7 high ozone days during the 2020–2022 testing period. It also had 20.8 high particle days and an annual particle pollution concentration average of 11.6 µg/m^3.
19. Las Vegas–Henderson, NV
Back into the desert, we have the Las Vegas–Henderson, NV area. This metro area ranked number 19 worst overall for air quality according to the American Lung Association’s State of the Air report. It ranked number 11 worst for high ozone days out of 228 metropolitan areas surveyed. Additionally, for 24-hour particle pollution, the area ranked 23 worst in the nation.
Its annual particle pollution concentration average was the 20th worst in the nation. Throughout the three-year testing period, the Las Vegas–Henderson area had 19.8 high ozone days, 7.5 high particle days, and an annual particle pollution concentration average of 10.8 µg/m^3.
20. Yakima, WA
Yakima, WA came in 20th overall in the worst air quality in America. The American Lung Association wasn’t able to collect any data regarding Yakima’s ozone pollution. However, its particle pollution was bad enough for it to land in the top 25 areas without any influence from ozone ratings.
Yakima ranked 12th worst for 24-hour particle pollution and annual particle pollution, out of 223 and 204 metropolitan areas surveyed in total. During the testing period, the area experienced 18.3 high particle days and had an annual particle pollution concentration average of 11.8 µg/m^3.
21. Seattle–Tacoma, WA
Staying within the Washington State borders, Seattle–Tacoma came in 21st worst of the cities with the dirtiest air in the nation, according to the American Lung Association. The metro area ranked 45th worst for high ozone days out of the 228 areas surveyed.
In 24-hour particle pollution levels, the area was the 13th worst and it was 75th worst for annual particle pollution out of 204 metro areas in the study. During the 2020–2022 testing period, the area clocked 4 high ozone concentration days, and 15.8 high particle days, and had an annual particle pollution concentration average of 8.9 µg/m^3.
22. Dallas–Fort Worth, TX
Coming in 22nd worst in the nation for air quality is Dallas–Fort Worth in Texas. The area ranked 13th worst for high ozone days, 85th worst for 24-hour particle pollution levels, and 48th worst for annual particle pollution average.
During the testing period, the Dallas–Fort Worth area experienced 17.7 high ozone days, 1 high particle day, and an annual average particle pollution concentration of 9.4 µg/m^3.
23. Detroit–Warren–Ann Arbor, MI
Moving over to the Great Lakes, we have Detroit–Warren–Ann Arbor in Michigan. The area ranked 33rd worst for high ozone days in the American Lung Association’s State of the Air study for 2024.
It also ranked 35th worst for 24-hour particle pollution levels and 13 worst for annual particle pollution averages. During the testing period, this area experienced 5.7 high ozone days, and 5.8 high particle days, but had an annual particle pollution average of 11.7 µg/m^3.
24. Missoula, MT
Missoula, Montana ranked the 24th worst area to live if air pollution is problematic for you. While it tied for 1st for the best city to live in for low ozone pollution, it ranked 14th worst for 24-hour particle pollution and 29th worst for annual particle pollution levels.
The city had a laudable 0 high ozone days during the testing period. However, the 14.3 high particle pollution days and 10.1 µg/m^3 annual average particle pollution concentration are still worrying for those with lung diseases.
25. New York–Newark, NY–NJ–CT–PA
People cool off on the beach in Coney Island on July 6, 2023, in the Brooklyn borough of New York City. As global warming continues to raise temperatures around the world, heat records are being broken at an unprecedented rate.
New England almost skipped out on the top 25 worst out of the cities with the dirtiest air in America, but we see you there Connecticut. The New York–Newark area of New York, New Jersey, Connecticut, and Pennsylvania ranked 25th worst in the nation for air quality.
It was ranked 13th worst for high ozone days out of 228 metropolitan areas, 64 worst for 24-hour particle pollution, and 73 worst for annual particle pollution. During the testing period, the area experienced 17.7 high ozone days, 1.7 high particle days, and an annual particle pollution concentration average of 9 µg/m^3.