5 Cities with the Best Air Quality in the U.S.

The American Lung Association’s latest State of the Air report shows a concerning decline in air quality across the U.S., but some cities still stand out for their clean air. This year, only 35 cities had zero high ozone days, and just 22 cities had no days with high levels of short-term particle pollution—a sharp drop from last year’s 55 and 75 cities, respectively.

Only two cities, Bangor, Maine, and San Juan-Bayamón, Puerto Rico, made the clean air honor roll for all three pollution measures: ozone, short-term particle pollution, and year-round particle pollution. They each earned top marks and remain the cleanest cities to live in, according to the report.

Interestingly, Bangor was number one for year-round particle pollution last year, but falls to number five this year. Honolulu is the only other city from last year's top five to remain in the top this year, jumping from fourth to first place (tied with Casper, Wyoming). Other former top-ranked cities lost their spots due to at least one day of elevated particle pollution.

Unhealthy air can lead to a poor quality of life and multiple health problems. Dirty air can instigate emergency room visits, poor lung development in children, and even death in some cases.

If you’re looking to breathe in some cleaner air, look to these metro areas, which the American Lung Association deemed this year's cleanest in the US.

Casper de-throned Bangor, Maine, from the top spot this year—and tied with Honolulu, Hawaii, for the cleanest city in the country based on year-round particle pollution.

Cowboy State Daily highlights this achievement, noting that Casper recorded the cleanest air in the nation, thanks in part to Wyoming’s geography and weather patterns that help disperse pollutants.

“In a notable achievement, Casper tied with Honolulu, Hawaii, for the number one ranking on the list of cleanest cities for year-round particle pollution,” said Will Barrett, the Lung Association’s senior director for clean air advocacy, in an interview with Cowboy State Daily.

The article also points to the role of strong winds in Casper and Cheyenne that help clear out pollution—an advantage over cities in more stagnant valleys (like Salt Lake City, Utah). Despite the win for Casper, the report urges continued support for clean air protections, warning that setbacks in federal regulations could reverse progress.

Once again, Honolulu soars to the top of the American Lung Association’s clean air rankings—this time tying with Casper, Wyoming, for the #1 spot in the nation for year-round air quality. Climbing from fourth place last year, this island paradise proves that clean living isn’t just a perk of tropical geography—it’s the result of dedication.

The Hawai‘i Department of Health’s  Clean Air Branch works year-round to protect the state’s famously fresh air, ensuring Honolulu residents can breathe easy while enjoying ocean breezes, mountain views, and urban island life at its best.

Ranked the third-cleanest city for year-round air quality, the Kahului-Wailuku area on Maui is more than just a scenic paradise—it’s a haven for clean air. Nestled between the lush ʻĪao Valley and Kahului Bay, these neighboring towns offer a unique blend of natural beauty and local charm.

Wailuku, the county seat, is known for its family-run shops and wooden storefronts near the iconic ʻĪao Valley State Park, while Kahului is a vibrant hub with Maui’s largest mall and the island’s main airport. Together, these communities combine small-town warmth with big environmental wins—making them a top choice for clean, breathable living.

Bozeman, Montana, ranked fourth in the nation for clean year-round air, proves that fresh mountain air isn’t just a natural gift—it’s a community commitment. Nestled in the scenic Gallatin Valley and surrounded by the Rockies, Bozeman couples its stunning landscape with forward-thinking environmental action.

The city’s Climate Plan targets greenhouse gas reduction, while its Pollution Prevention Program protects local air, water, and land. Bozeman also supports residents with rebates for air purifiers, guidance on wildfire smoke protection, and water conservation resources. Clean air in Bozeman isn’t just luck—it’s policy, planning, and pride.

For the third year in a row,  Bangor ranks among the cleanest places to live in the U.S. for air quality. While it dropped to number five for year-round particle pollution, Bangor is still one of only two cities nationwide to earn clean grades across all three major categories: ozone, short-term particle pollution, and year-round particle pollution.

From 2021 to 2023, Bangor didn’t register a single day with unhealthy ozone or particle pollution levels—earning it a solid “A” rating. But experts caution that staying at the top takes effort.

“Thankfully, people in the Bangor metro area are breathing some of the least polluted air in the country,” Lance Boucher of the American Lung Association said in a WMTW report. “However, keeping our air clean takes work.”

Find out what’s helping Bangor lead the way by exploring the Maine Department of Environmental Protection's list of air quality programs.

• The Air Pollution Control Act of 1955, was the nation's first legislation aimed at air pollution.
• Air pollution particles can be smaller than 1/30th the diameter of your hair, making them ideal for inhalation and passing by the body's defenses.
• Particle pollution can lead to increased risk of lung cancer, heart attacks, strokes, and emergency room visits.
• The increase in wildfires across the U.S. adds to particle air pollution via spreading smoke.
• The American Lung Association's, "Compare Your Air" tool will let you compare air quality in these top cities to your own metro area. 
• More than 125 million people live in areas that earned an F grade for ozone pollution. 
• 3 in 10 people, including millions of infants and children, live in areas deemed high risk for pollution exposure. 
• Growing risks associated with wildfires led the US to experience 135 purple and 79 maroon air quality days nationwide between 2020 and 2023. 
• Four of the five worst cities for year-round air pollution were located in California: Bakersfield, Visalia, Fresno, and the Los Angeles metro areas. Eugene, Oregon, was the only one in the top five outside of the state. 
• People of color, those living below the poverty line, and folks with underlying health conditions are most at risk of harm from pollution and poor air quality. Over 26 million people of color live in counties with failing grades for ozone, year-round, and short-term particle pollution.
• Check the air quality forecast in your area before exercising or working outdoors. 
• Using a portable air purifier with a HEPA filter can help reduce triggers for people with asthma.
• If you or someone you love has asthma, develop an asthma action plan to deal with environmental triggers at home.

Methodology

We used the American Lung Association's "State of the Air" report, which identified the cities in the U.S. with the cleanest air.

See the American Lung Association's full methodology.

The report, published on April 23, 2025, covers air quality metrics for the years 2021, 2022, and 2023.

1. American Lung Association, "2025 State of the Air." 
2. Environmental Protection Agency, "What is a HEPA filter?"