About 2 in 5 Americans live in areas with unhealthy air. Here's how where you live impacts the air you breathe.

Americans are increasingly breathing toxic air as ozone smog rises and wildfires become more common and intense due to climate change.

Poor air quality impacts more than your lungs. Despite decades of progress, a 2024 American Lung Association report found that 11.7 million more people are breathing unhealthy air compared to last year.

Northwell Health partnered with Stacker to look at the most polluted cities in the United States using data from the Environmental Protection Agency and the American Lung Association.

One of the main drivers of the increase is particle pollution, which comes from cars, factory emissions, and wildfire smoke. Cities that have experienced massive droughts and wildfires in recent years have among the worst air quality.

So far this year, there have been more than 20,000 wildfires, spanning 2.3 million acres, well above the 10-year average.

What was once a largely regional phenomenon is now felt in other parts of the country. Last year, New York City skies turned an eerie orange when smoke from Canadian wildfires wafted across the Eastern United States.

Some groups are more impacted than others. The American Lung Association report found that people of color are 2.3 times more likely than white Americans to live in a place with poor air quality. Historic redlining and housing discrimination play a key role, as Black people, in particular, are more likely to live near hazardous waste sites and other industrial facilities.

The EPA measures air quality based on the concentration of five major pollutants, including ozone levels and particulate matter. The Air Quality Index scales from 0 to 500, with anything over 300 considered hazardous.

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Western cities top the list of most polluted

Globally, more than 6.5 million people die each year due to air pollution. Exposure to polluted air can inflame cells and increase the risk of chronic diseases, including respiratory illness or cancer. Sensitive groups—such as people with heart or lung disease, asthma, children, and older adults—can be particularly susceptible to poor air quality.

Cities in the West and Southwest are among the most polluted, with California topping the list of most affected metro areas. Bakersfield, California, has experienced 150 days of unhealthy air on average, meaning its residents spend nearly half the year breathing unsafe air.

Home to three oil refineries, Bakersfield has long been considered one of the most polluted cities in the country. In 2008, it paid $25,500 in penalties for violating state air quality regulations. Earlier this year, the Sherwood fire in surrounding Kern County burned through 350 acres, spurring evacuation orders and destroying at least one home.

What's being done to improve air quality

The Biden administration has taken a multistep approach to reducing air pollution risks. In 2021, the administration created ​​the Wildland Fire Mitigation and Management Commission to explore how federal agencies can improve wildfire management. It also strengthened pollution standards and offered incentives to buy electric vehicles and energy-efficient household appliances.

State and local governments are also setting standards and creating climate action plans. California's Air Resources Board, established in 1967, works to reduce air pollution and the effects of climate change in the state. It is the only state allowed to set its own vehicle emissions standards.

At the individual level, the American Lung Association recommends reducing car use and conserving electricity when possible. Taking advantage of tax credits to buy an electric car or upgrade home appliances can also reduce overall carbon emissions and improve air quality.

However, as air quality continues to be impacted by climate change, the most meaningful improvements must come at the institutional level. In April, the EPA finalized new air pollution rules for power plants, projected to reduce overall carbon pollution by 1.38 billion metric tons through 2047—roughly the same annual emissions as 328 million gas-powered cars.

Story editing by Alizah Salario. Additional editing by Kelly Glass. Copy editing by Paris Close.

This story originally appeared on Northwell Health and was produced and distributed in partnership with Stacker Studio.