--- title: Most Polluted Cities: United States Cities with Worse Air Quality description: More than 40% of Americans live in a place with unhealthy air quality, according to a new report. But not all cities are created equal. canonical: https://time.com/3840001/most-polluted-cities-2015/ author: Justin Worland article:opinion: false article:content_tier: free article:published_time: 2015-04-29T15:41:10.000Z article:modified_time: 2026-05-11T05:04:18.485Z article:section: Health og:title: Most Polluted Cities: United States Cities with Worse Air Quality og:description: More than 40% of Americans live in a place with unhealthy air quality, according to a new report. But not all cities are created equal. og:url: https://time.com/3840001/most-polluted-cities-2015/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production og:image:width: 1200 og:image:height: 675 og:image:alt: TIME og:type: article twitter:card: summary_large_image twitter:title: Most Polluted Cities: United States Cities with Worse Air Quality twitter:description: More than 40% of Americans live in a place with unhealthy air quality, according to a new report. But not all cities are created equal. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production --- # These Are America's 10 Most Polluted Cities > Sponsored content. Supplied in partnership with TIME. 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There is no cost and no subscription requirement. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-network-2026q3/newsletters?i=a3a4ffb2-3d27-4123-a525-37444f418a05&cr=time-nl-network-2026q3-v1)  by [Justin Worland](https://time.com/author/justin-worland/)  ## Justin Worland Senior Correspondent Apr 29, 2015 3:41 PM UTC  by [Justin Worland](https://time.com/author/justin-worland/)  ## Justin Worland Senior Correspondent Apr 29, 2015 3:41 PM UTC More than 40% of Americans live in a place with unhealthy air quality, according to a new [report](http://time.com/wp-content/uploads/2015/04/ala%5Fstate%5Fof%5Fthe%5Fair%5F2015.pdf) from the American Lung Association. But, when it comes to how bad that air pollution can get, there’s a real range. Los Angeles, which has some of the most polluted air in the country, experiences unhealthy levels of particle pollution for the equivalent of nearly a month out of each year and unhealthy ozone pollution for the equivalent of more than two months annually. Six cities, all much smaller in size, went an entire year without an unhealthy day of either. Particle pollution refers to the toxic exhaust emitted by processes like smoking or driving a car, and ozone pollution refers to an invisible substance present in smog. Exposure to either pollutant can exacerbate breathing problems and increase residents’ chance of developing cancer. People most harmed by air pollution include those with cardiovascular diseases, diabetes and asthma, as well as children and the elderly. The report also notes that great disparities in risk exist even _within_ cities. People who live close to highways or busy roads, for instance, are at increased risk, and overall, low socioeconomic status is associated with exposure to poorer air quality. The report offers a few guidelines for individuals to manage pollution, like avoiding high-traffic areas, but the report also suggests a more top-level approach to public health: strengthening clean-air regulation. Here are the U.S. cities with the most ozone pollution in 2015: 1\. Los Angeles-Long Beach, CA 2\. Visalia-Porterville-Hanford, CA 3\. Bakersfield, CA 4\. Fresno-Madera, CA 5\. Sacramento-Roseville, CA 6\. Houston-The Woodlands, TX 7\. Dallas-Fort Worth, TX-OK 8\. Modesto-Merced, CA 9\. Las Vegas-Henderson, NV-AZ 10\. Phoenix-Mesa-Scottsdale, AZ The six cities without any days of unhealthy ozone or particle pollution are Bismarck, N.D.,Cape Coral-Fort Myers-Naples, Fla., Elmira-Corning, N.Y., Fargo-Wahpeton, N.D.-Minn., Rapid City-Spearfish, S.D. and Salinas, Calif. ### See the Worst Place to Breathe in America  A passenger train travels through town past a refinery in Bakersfield, Calif. Lexey Swall—GRAIN  Oil pumps and scarred earth can be seen for miles in an area of North Bakersfield called the Bluffs. A Cogeneration Plant sits in the middle of the fields and is one of California's top polluters. Lexey Swall—GRAIN  A dust storm blows through Bakersfield, Calif. Dust is a pervasive problem in the area. Lexey Swall—GRAIN  Yareli Gonzalez, 7, suffers from asthma and receives two nebulizer treatments per day, indefinitely. Gonzalez lives in Shafter, a rural farming town in Kern County, Calif. Kern County sits at the southern end of the San Joaquin Valley, an area known for having the worst air in the nation due to dust, smog and high levels of ozone. Lexey Swall—GRAIN  Asthma educator Sharon Borradori, left, shows Margarita Hernandez, center, and her husband, Severo Velasco, right, how their 2-year-old son, Mauricio Velasco will use an inhaler when he's older. Mauricio was recently released from the hospital after suffering from an extreme asthma attack. Lexey Swall—GRAIN  Children practice sports on a field at Bakersfield High School which backs up against the train yard that runs through the middle of town in Bakersfield. Lexey Swall—GRAIN  Young football players exercise on the stadium of Bakersfield High School. Bakersfield High is the oldest high school in town and the mascot, the Driller, is directly tied to area industry. Lexey Swall—GRAIN  Benjamin Swall, 14, waits for his brother's football practice to end at Bakersfield High School. Lexey Swall—GRAIN  Red Simspon, a country music legend and Bakersfield native, smokes a cigarette outside of the Rasmussen Senior Center in Oildale, north of Bakersfield. Lexey Swall—GRAIN  Merced Mendoza moves irrigation pipe in a field that will be used to grow alfalfa. The field is adjacent to and owned by Kern Oil and Refining Co. Mendoza is a leader for a men's group at Victory Outreach Church in Bakersfield that rents the land from the refinery to grow alfalfa that is then sold to a local dairy for feed. The money earned from the feed helps fund the men's program for the church. This symbiotic relationship between resource companies and the community are played out throughout the region. Lexey Swall—GRAIN  Percolation ponds fill up with runoff water from nearby Belridge Oil Fields in Eastern Kern County. As the water evaporates, leaving oil residue, hydrogen sulfide, methane and volatile organic compounds, or VOCs, are released in to the air. Lexey Swall—GRAIN  Dust devils can be seen reaching toward the sky during dry months in Bakersfield. Dust is a pervasive problem that contributes to diminished air quality. The problem is exacerbated by the current drought in California. Lexey Swall—GRAIN  Lucy Clark, 72, lives in the foothills north of Bakersfield. Her home sits at 2200 feet, which is about the elevation where the visible layer of smog begins to hang in the air. Because of this, Clark, who suffers from asthma, wears a mask every day she walks out to get the mail. Lexey Swall—GRAIN  Elk Hills Power plant provides electricity to power Occidental Elk Hills oil field. Oxy's Elk Hills field is one of the largest oil fields in the United States and the natural gas power plant can produce 550 megawatts of electricity. Lexey Swall—GRAIN  Samantha Olivarez, 9, left, and her cousin, Daisy Olivarez, 7, play in front of their home in Arvin, Calif. The homes across the street were evacuated after a gas pipe leaked underground. According to reports, the 40-year-old pipe was leaking for as long as two years before it was detected. Olivarez's family is worried about possible health risks in the area due to the pollution. Lexey Swall—GRAIN ### Los Angeles-Long Beach, CA  Pier G, foreground, sits idle at the Port of Long Beach in Long Beach, Calif., Dec. 3, 2012. Tim Rue—Bloomberg/Getty Images Los Angeles has topped the list of the most ozone-polluted cities in 15 out of the last 16 American Lung Association reports. And though the city has actually reduced the total annual days of ozone pollution, there was still an unhealthy level of ozone still for more than two months. ### Visalia-Porterville-Hanford, CA  Canadian geese fly over a tumbleweed-covered fallow field at sunrise on Feb. 5, 2014 near Visalia, California. David McNew—Getty Images The number of days of unhealthy ozone levels in Visalia, a Central California metropolitan area of more than 600,000 people, declined to the lowest level in the 2015 report. ### Bakersfield, CA  Oil pumps stand at the Chevron Corp. Kern River oil field in Bakersfield, Calif., March 29, 2011. Ken James—Bloomberg/Getty Images Mountains that surround Bakersfield on three sides trap pollution in this central California city. ### Fresno-Madera, CA  The downtown Fresno skyline with heavy haze is seen, Jan. 17, 2014. Craig Kohlruss—MCT/Getty Images Fresno, another city in central California, is home to the greatest number of at-risk people, according to the report. ### Sacramento-Roseville, CA California’s capital city is home to more than 200,000 people with asthma, including 50,000 children. ### Houston-The Woodlands, TX  A boat passes a refinery standing along the Houston Ship Channel in Houston, Texas, Jan. 30, 2014. Scott Dalton—Bloomberg/Getty Images Houston, home to a significant number of heavy industry companies, has instituted a number of policies in recent years that have actually improved air quality. ### Dallas-Fort Worth, TX  A 150-foot derrick towers over traffic along Interstate 35W, left, positioned on a natural gas well site on Dec. 17, 2008 in Fort Worth, Texas. Robert Nickelsberg—Getty Images The Dallas metropolitan area had an average of 16 days of unhealthy ozone pollution each year, according to the report. ### Modesto-Merced, CA Modesto is yet another Central California city to fail pollution standards. ### Las Vegas-Henderson, NV  The M Resort in Henderson, Nev. on May 21, 2012. Steve Marcus—AP Las Vegas has hundreds of thousands of at-risk residents, including more than 175,000 people with asthma. ### Phoenix-Mesa-Scottsdale, AZ  Morning view from the top of Piestawa Peak looking Southeast over Scottsdale, Paradise Valley, and Phoenix, Ariz. Tim McGuire—Corbis Phoenix, a newcomer to the top-ten list, saw reduced air quality in recent years. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/3840001/most-polluted-cities-2015/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/3840001/most-polluted-cities-2015/"},"headline":"These Are America's 10 Most Polluted Cities","datePublished":"2015-04-29T15:41:10.000Z","dateModified":"2026-05-11T05:04:18.485Z","description":"California is well-represented on the list","url":"https://time.com/3840001/most-polluted-cities-2015/","keywords":["Public Health"],"thumbnailUrl":"","author":[{"@type":"Person","name":"Justin Worland","jobTitle":"Senior Correspondent","url":"https://time.com/author/justin-worland/"}],"articleSection":"Health","image":[],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/public-health/","name":"Public Health"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/3840001/most-polluted-cities-2015/","name":"These Are America's 10 Most Polluted Cities"}}]}] ```