15 US Cities With the Worst Air Quality

Air pollution over Los Angeles
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The American Lung Association's State of the Air Report is essentially a report card for the country’s air quality. It measures ozone pollution, short-term particle pollution, and year-round particle pollution to reflect the severity of the country’s air contamination.

While the U.S. has improved in certain aspects throughout the years, the country still has a long way to go. In 2021, the report found that 41.1% of Americans (that’s about 135 million people) are living in places with unhealthy levels of ozone or particulate air pollution.

The study also revealed that people of color are disproportionately affected and are over 60% more likely to live in a county with a failing grade in at least one pollutant. Additionally, over 15.8 million people living at or below the federal poverty line live in counties with at least one failing grade for ozone or particulate pollution, while about 2.3 million children and 9.2 million adults with asthma live in counties with at least one failing pollutant.

Using an average between the three measurements (ozone, short-term particle, and year-round particle pollution) we are bringing you 15 cities with the worst air quality in America.

1
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Bakersfield, California

Fruit trees in Bakersfield, California

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Bakersfield, California, was cited as the most polluted city in terms of year-round particle pollution for the second year in a row, beating out its fellow Central California cities of Fresno and Visalia.

The city, where about two-thirds of the population identify as people of color, also ranks second for ozone pollution and third for 24-hour particle pollution.

Bakersfield is known for its high-emission industries, such as large-scale agriculture and oil refineries, and made headlines when it had a massive population growth spurt, going from 2,000 residents to over 100,000 over ten years into 2010.

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Fresno, California

Downtown Fresno, California at dusk
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The agricultural cities of Fresno-Madera-Hanford ranked second for both yearly and daily particle pollution in 2021, as well as fourth for high ozone days. This would come as no surprise to residents, who are well aware of the hot, dry weather and the surrounding mountains that cause an inversion layer of trapped pollution.

According to the local newspaper, Fresno’s air district offers grants and incentive programs to help businesses and residents make the switch to zero-emission technologies in an effort to curb the city’s infamous air pollution.

3
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Visalia, California

A field in Visalia, California
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Less than 50 miles southeast of Fresno, the city of Visalia ranks third in both ozone and annual particulate air pollution, but jumps down the list to 11th for 24-hour particle pollution.

Suffering from the same geography as the rest of Central California, where pollution naturally settles in the landscape, Visalia is also a hotspot for industrial dairies. Pollution from large-scale cattle operations in Visalia even prompted local conservation groups to team up with the Center for Biological Diversity in filing an air pollution lawsuit against Tulare County, citing that the county’s dairy businesses produced 63% of the entire county’s GHG emissions in 2013.

4
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Los Angeles, California

Downtown Los Angeles haze
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Notorious for its air pollution, the city of LA has (unsurprisingly) earned a spot on the list, mainly due to its high number of dangerous ozone days. Los Angeles (the ranking also includes the city of Long Beach) has remained the city with the worst ozone pollution in the nation for all but one of the 22 years since the State of the Air report began. It also ranked sixth for daily particle pollution exposure and fourth for annual particle pollution, with just over a million adult residents living with chronic asthma.

The poor air hasn’t gone unnoticed by city officials, who implemented a Sustainable Cities Plan in 2015 with a goal to cut down unhealthy air pollution days from 40 to zero by 2025.

5
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Fairbanks, Alaska

Downtown Fairbanks, Alaska in winter
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While Alaska certainly isn’t the first place many of us think of in terms of pollution, the city of Fairbanks was named the metropolitan area with the worst short-term particle pollution for the first time in 2021. What’s more, because of significant wildfires in 2019, Fairbanks recorded at least three days of hazardous air pollution levels, the highest level in the Air Quality Index.

According to Earthjustice, sources of harmful air pollution in Fairbanks range from outdoor wood burning and coal burning to automobiles and industrial facilities. The situation is so dire that Fairbanks community groups have sued the United States Environmental Protection Agency in the past, since the agency has not taken adequate action to address it.

6
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San Jose, California

Downtown San Jose, California with mountains in the background
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San Jose, San Francisco, and Oakland ranked fourth for 24-hour particle pollution in 2021, beating out nearby Sacramento. The city is a major hub for Silicon Valley, which has been linked to increased traffic pollution and even groundwater pollution from industrial manufacturing plants in the past.

Throughout the entire Bay Area, the particularly hazy or smoggy days are regulated by the Bay Area Quality Management District with Spare the Air Days; unfortunately, the number of ozone Spare the Air alerts has doubled every year since 2018.

7
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Sacramento, California

Aerial view of the Sacramento River in Sacramento, California
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Ranking sixth for high ozone days, Sacramento is another Northern California city that continues to see record high temperatures and wildfires caused by climate change. The high temps and subsequent fires are some of the largest contributing factors to air pollution levels.

Still, the city's ranking (which also includes Roseville) fares better in terms of annual particle pollution, ranking 24th out of the 199 metropolitan cities examined in the State of the Air Report.

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Phoenix, Arizona

Cacti over Phoenix, Arizona
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The capital of Arizona ranked fifth in high ozone days and eighth for annual particle pollution. Combined with the city of Mesa included in the ranking, the large city has a population of 1.6 million, and most of its year-round particulate matter is produced by wood burning in fireplaces, fireworks during winter holidays, as well as car and truck exhausts.

In an article for a local newspaper, JoAnna Strother, the Lung Association's director of advocacy for the Southwest region, said that “everyone has to play a role, but certainly the federal government needs to set stronger standards. These are health protections that have been put in place that we really can't afford to roll back.”

9
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Medford, Oregon

A bridge in Medford, Oregon
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Like the rest of the Pacific Northwest, Oregon’s cities of Medford and Grants Pass suffer from wildfire smoke that becomes trapped in the valley, leading to poor air quality and failing marks from the State of the Air Report.

The tiny smoke particles are small enough to breathe in, triggering the area’s estimated 27,541 asthmatic adults and 4,323 asthmatic children. While the city ranks fifth for annual particle pollution, it comes in all the way at 57th for ozone.

10
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El Centro, California

The city of El Centro, California near Mexico
Wikimedia Commons / JacobSA2019 / CC BY-SA 4.0

The city of El Centro, where nearly 90% of the population is people of color, sits on the border between California and Mexico. The city ranked 10th for annual particle pollution and 15th for high ozone days in the report. Imperial County, where the city is located, has been described by civic organizers as "the poster child of what the climate crisis looks like" in local media.

The agricultural community shares its air with two other jurisdictions, the South Coast Air Quality Management District to the north and the Mexican city of Mexicali to the south.

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Yakima, Washington

Vineyards in Yakima, Washington
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An area known for its wine industry, Yakima ranked fifth for 24-hour particle pollution and 26th for annual particle pollution in 2021. The poor air quality has been attributed to the increasing wildfires and their related air pollution, which is blown into the valley by the wind coming from California and Oregon.

The city also sees poor air quality from domestic wood burning in the winter months, which can bear more than three times the concentration of particulate pollution than in summer months. In order to alleviate pollution levels during the winter, the local Yakima Regional Clean Air Authority institutes burn bans during temperature inversions.

12
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San Diego, California

Convention Center in San Diego, California
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The Pacific Coast cities of San Diego-Chula Vista-Carlsbad ranked seventh for high ozone days in 2021. On the other hand, San Diego is in better shape when it comes to particle pollution, ranking 37th for 24-hour particle pollution and 43rd for annual particle pollution.

While addressing the air pollution situation, San Diego County Supervisor Nathan Fletcher told reporters at The San Diego Union-Tribune that “more people die from air-related issues than they do from breast cancer. I think this should serve as a sobering reminder but also a wake-up call for our policymakers that we have to do more.”

13
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Logan, Utah

A church in Logan, Utah in winter
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Logan ranked seventh for 24-hour particle pollution, but stayed low in the other two categories at 157th for annual particle pollution and 119th for ozone in 2021.

A study conducted by Utah’s own Brigham Young University showed that the air pollution in the state results in between 2,500 and 8,000 premature deaths each year, decreasing the median life expectancy by 1.1 to 3.6 years. The research also showed that economic losses connected to air quality ranged between $750 million and $3.3 billion, mostly from health care expenses and crop loss, a far cry from the $10 million that the Utah Legislature appropriated toward programs to reduce pollution in 2020.

14
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Denver, Colorado

Skyline against Denver, Colorado
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The Colorado capital city of Denver (along with nearby Aurora) ranked eighth for ozone, 33rd for daily particle pollution, and 36th for annual particle pollution in 2021.

In 2020, federal records showed that Denver residents inhaled hazardous air pollution at hazardous levels for more than 260 days each year for the preceding two years. In 2019, the state Air Pollution Control Division revealed that the EPA had reclassified the city as a serious violator of federal air regulations after it failed to meet health standards for 10 years straight.

15
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Redding, California

Sunset in Redding, California
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Located in Northern California near Lake Shasta, the cities of Redding and Red Bluff are also affected by wildfires on a regular basis. In 2021, it ranked 20th for high ozone days and 25th for annual particle pollution, but came in eighth for 24-hour particle pollution.

As fires raged across the region in 2020, Redding residents experienced visibly floating particles of ash in the air, giving the area a smokey haze but still registering air quality as “good,” since the measurements were taken in terms of tiny, particulate matter rather than large particles.