Nearly 2 in 5 Americans live amid unhealthy air pollution levels

As many as 131.2 million people in the U.S. live where the air quality gets failing grades due to too-high levels of ozone or particle pollution. And it’s a problem that’s been getting worse, despite “decades of progress cleaning up air pollution,” according to the 2024 “State of the Air” report from the American Lung Association.

The report finds that an additional 11.7 million people are breathing unhealthy air compared to 2023′s reckoning, but notes the 2024 report uses the Environmental Protection Agency’s “new, more protective national air quality standard for year-round levels of fine particle pollution, which allows for the recognition that many more people are breathing unhealthy air than was acknowledged under the previous weak standard.”

The association said that despite progress, “people in the U.S. experienced the most days with ‘very unhealthy’ and ‘hazardous’ air quality due to particle pollution in 25 years.”

The burden is especially high for people of color, per the association, which said that while they make up 41.6% of the overall population, they are more than half of the people who live in counties with at least one failing air quality grade. Among counties that fail on all three pollution measures, people of color make up 63% of the population.

“We have seen impressive progress in cleaning up air pollution over the last 25 years, thanks in large part to the Clean Air Act. However, when we started this report, our team never imagined that 25 years in the future, more than 130 million people would still be breathing unhealthy air,” Harold Wimmer, president and CEO of the American Lung Association, said in a written statement. “Climate change is causing more dangerous air pollution. Every day that there are unhealthy levels of ozone or particle pollution means that someone — a child, grandparent, uncle or mother — struggles to breathe. We must do more to ensure everyone has clean air.”

Health risks

Health risks associated with poor air quality are well known and include an increased risk of giving birth prematurely, as well as lung and heart disease. Studies show that heart attacks may increase on high–pollution days. According to the report, people also become more susceptible to infections, cognitive decline and metabolic disorders.

But there are also health effects particular to different types of bad air.

For example, particle pollution — typically from vehicles, factories, power plants, equipment like lawn mowers, wood-burning stoves and wildfires — can be deadly, sparking heart attack, stroke and respiratory crises. Both long-term and short-term exposure pose risks, but long-term increases a special array of problems for women who are pregnant and their babies, including preterm birth, infant death, miscarriage, neurological impairment, poor lung development and asthma.

Adults exposed long term may face serious health challenges, too, including more heart and lung disease, increased risk of diabetes, lung disease, Parkinson’s and dementia. And poor quality air is linked to an increase in clinical depression and anxiety.

Risk also varies depending on a person’s health and other factors.

Ozone pollution — from motor vehicles, chemical plants, refineries, gas stations, paint and other sources — is very hard on lungs, increasing irritation, exacerbating lung problems and increasing allergies, infections and asthma. It can lead to chronic obstructive pulmonary disease, too.

The damage ozone does to tissue, genes and proteins in the body can worsen other conditions, such as metabolic disorders, cognition and heart problems. It can decrease fertility and stunt development.

Gathering the data

The report uses air quality data from 2020-2022 that has been collected at all government levels at official monitoring sites in the U.S. The data is also used to rank metropolitan areas and counties.

Now in its 25th year, the annual report — like those before it — reflects “the successes of the Clean Air Act as emissions from transportation, power plants and manufacturing have been reduced in recent years.” But the report said that the findings “continue adding to the evidence that a changing climate is making it harder to protect human health. High ozone days and spikes in particle pollution related to extreme heat, drought and wildfires are putting millions of people at risk and adding challenges to the work that states and cities are doing across the nation to clean up air pollution.”

East vs. West

According to the American Lung Association, there is now “marked disparity between air quality in eastern and western states, especially for the daily measure of fine particle pollution.” It notes that just four large counties in three states east of the Mississippi River earn failing grades for daily fine particle pollution spikes, compared to those spikes found routinely in 108 counties in 16 Western states.

The story is somewhat different for year-round particle pollution. While most of the 119 counties earning failing grades there are in the West, the new air-quality standard shows problems in Eastern and Midwestern states, too: 47 counties in 12 states east of the Mississippi River had unhealthy year-round fine particle pollution.

Per the report, “Bakersfield, California, topped the list for worst short-term particle pollution again this year. Bakersfield also continued as the metropolitan area with the worst level of year-round particle pollution for the fifth year in a row. Los Angeles remains the city with the worst ozone pollution in the nation, as it has been in 24 of the 25 years of reporting in ‘State of the Air’ — even though city residents are exposed to unhealthy levels of ozone an average of 55 days a year fewer now than they were in 2000.”

Metro area rankings

More than 80 cities made the list of “cleanest” U.S. cities by ozone air pollution. They weren’t ranked, since all scored the same, the report said.

The top 10 cleanest metro areas on the measure of year-round particle pollution were, in order: Urban Honolulu, Hawaii; Casper, Wyoming; Kahului-Wailuku-Lahaina, Hawaii; Wilmington, North Carolina; Bangor, Maine; Cheyenne, Wyoming; Duluth, Minnesota-Wisconsin; Colorado Springs, Colorado; and tied for ninth, Anchorage, Alaska and St. George, Utah.

The top 10 cleanest metro areas for short-term particle pollution were Asheville-Marion-Brevard, North Carolina; Bangor, Maine; Bloomington-Bedford, Indiana; Burlington-Fort Madison-Keokuk, Iowa-Illinois-Missouri; Cape Coral-Fort Myers-Naples, Florida; Champaign-Urbana, Illinois; Charlottesville, Virginia; Cleveland-Indianola, Mississippi; and College Station-Bryan, Texas.

The most ozone-polluted metro areas were: Los Angeles-Long Beach, California; Visalia, California; Bakersfield, California; Fresno-Madera-Hanford, California; Phoenix-Mesa, Arizona; Denver-Aurora, Colorado; Sacramento-Roseville, California; San Diego-Chula Vista-Carlsbad, California; Salt Lake City-Provo-Orem, Utah; and Houston-The Woodlands, Texas.

The metro areas with the most particle pollution year-round were: Bakersfield, California; Visalia, California; Fresno-Madera-Hanford, California; Eugene-Springfield, Oregon; San Jose-San-Francisco-Oakland, California; Los Angeles-Long Beach, California; Sacramento-Roseville, California; Medford-Grants Pass, Oregon; Phoenix-Mesa, Arizona; and Fairbanks, Alaska.

The metro areas with the most short-term particle pollution were: Bakersfield, California; Fresno-Madera-Hanford, California; Fairbanks, Alaska; Eugene-Springfield, Oregon; Visalia, California; Reno-Carson City-Fernley, Nevada; San Jose-San-Francisco-Oakland, California; Redding-Red Bluff, California; Sacramento-Roseville, California; and Chico, California.