The 25 most dangerously polluted cities in the US

San Francisco, California.

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San Francisco, California.
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Flickr/Nicholas Raymond

More than 133.9 million Americans live in counties with unhealthy levels of air pollution, according to the American Lung Association’s 2018 “State of the Air” report. That figure is a 9 million person increase from last year’s report.

Pollution leads to various kinds of nasty health outcomes, including asthma, lung cancer, and shortened lifespans.

The new report rounds up air quality data from 2014 to 2016 in the United States. (Because air quality data is plentiful and complicated, the annual ALA reports look two years into the past.)

The report focuses on two key kinds of pollution: particles and ozone.

Particles include everything from dust kicked up during a drought to tiny particles floating in the air from forest fires or fossil fuels. Ozone, or smog, develops in the upper atmosphere when emissions from tailpipes and smokestacks cook in the sun’s heat.

Local pollution levels can be measured according to amounts of ozone in the atmosphere, number of days with extremely high particle pollution levels, or levels of year-round particle pollution. Each of those metrics yields different results. Los Angeles is the worst US city for ozone, for example, but not when it comes to year-round particle pollution, which is the ranking we use in this article.

Janice Nolen, the lead author of the ALA report, told Business Insider last year that local problems like car traffic can make cities’ ozone or particle problems worse, but that the overall issue is a national one. Even a place with strong environmental rules can be vulnerable to bad air flowing in from other parts of the country.

Here are the US metros with the worst year-round particle pollution. (The report notes that data is missing on all of Illinois and Mississippi, as well as two large counties in California.)


24 (tied). Little Rock-North Little Rock, Arkansas

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Downtown North Little Rock, Arkansas.
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Wikipedia Commons

24 (tied). Las Vegas-Henderson, Nevada-Arizona

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DAN CALLISTER Online USA Inc

22 (tied). Atlanta-Athens-Clarke County-Sandy Springs, Georgia

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Looking east across The Gulch from Centennial Olympic Park Drive in Atlanta, Georgia.
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Wikipedia Commons

22 (tied). Knoxville-Morristown-Sevierville, Tennessee

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Steam rises from a cooling tower at the Tennessee Valley Authority’s Watts Bar Nuclear Plant in Spring City, 50 miles south of Knoxville, Tennessee, U.S. on September 7, 2007.
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Thomson Reuters

21. Louisville-Elizabethtown-Madison, Kentucky-Indiana

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silicon640c/Flickr

18 (tied). Cincinnati-Wilmington-Maysville, Ohio-Kentucky-Indiana

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Flickr / Over-the-Rhine

18 (tied). Johnstown-Somerset, Pennsylvania

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Doug Kerr/ Wikimedia

18 (tied). San Luis Obispo-Paso Robles-Arroyo Grande, California

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Wikimedia

15 (tied). Birmingham-Hoover-Talladega, Alabama

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Bob Hall/Flickr

15 (tied). Harrisburg-York-Lebanon, Pennsylvania

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Wikimedia Commons

15 (tied). Houston-The Woodlands, Texas

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Thomson Reuters

14. Detroit-Warren-Ann Arbor, Michigan

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Shutterstock

13. Indianapolis-Camel-Muncie, Indiana

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KYPhua/Shutterstock

12. Philadelphia-Reading-Canton, Pennsylvania-New Jersey-Delaware-Maryland

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f11photo/Shutterstock

10 (tied). San Francisco-San Jose-Oakland, California

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Nicolas Raymond/Flickr

10 (tied). Cleveland-Akron-Canton, Ohio

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f11photo/Shutterstock

8 (tied). Lancaster, Pennsylvania

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Sam/Flickr

8 (tied). Pittsburgh-New Castle-Weirton, Pennsylvania-Ohio-West Virginia


7. El Centro, California

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El Centro, CA lies just north of the Mexican border
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NASA

6. Modesto-Merced, California

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Wikimedia

5. Fresno-Madera, California

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Shutterstock

4. Los Angeles-Long Beach, California

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Marika Bortolami/flickr

3. Bakersfield, California

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Shutterstock

2. Visalia-Porterville-Hanford, California

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Wikimedia

1. Fairbanks, Alaska

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FairbanksMike/Flickr

For more information and suggested policy solutions, you can read the full report.