'Striking and Distressing': More Than a Third of US Residents Breathe Unhealthy Air

Almost 120 million people–or more than a third of the U.S. population–are exposed to unhealthy levels of ozone or particulate matter pollution where they live.

That's the latest number from the American Lung Association's (ALA) annual State of the Air report, released Monday. And while it's smaller than the number in last year's report, there are alarming trends. Even more people of color are disproportionately exposed to unhealthy air, while the climate crisis is driving spikes in particulate matter pollution, especially in Western states.

"It is striking and distressing that 120 million people are still at risk from unhealthy air pollution," report lead author and ALA national senior policy director Katherine Pruitt told The Guardian. "Since around 2017, heat and drought driven by climate change has been undoing some of the progress that we should have made and been able to retain."

The report comes days after another study detailed how exposure to air pollution harms human health from cradle to grave. The ALA report used air quality data from across the U.S. to track two types of air pollution from 2019-21: particulate matter and ozone. Particulate matter pollution, also known as soot, is a potentially deadly pollutant linked to asthma, heart disease, strokes, and lung cancer. It is emitted by diesel engines, coal plants, wood stoves, and wildfires, among other sources. The report tracked both year-round exposure and short-term spikes that occur during events like wildfires. Ozone, or smog, has been compared to a "sunburn of the lung." Inhaling it can lead to coughing, irritation, asthma attacks, and potentially a shortened lifespan.

Overall, the report found that 17.6 million fewer people were exposed to air pollution than in last year's report, for a total of 119.6 million people. While that decrease reflects the success of environmental regulations, particularly at curbing ozone levels, it still leaves nearly 36% of the U.S. population breathing unhealthy air.

"The good news is that ozone pollution has generally improved across the nation, thanks in large part to the success of the Clean Air Act. In this year's 'State of the Air' report, we found that 19.3 million fewer people are living in areas with unhealthy levels of ozone pollution, also known as smog," ALA national president and CEO Harold Wimmer said in a press release. "However, the fact is that 120 million people still live in places with unhealthy air pollution, and not all communities are seeing improvements."

In fact, the racial air pollution gap has only widened. In last year's report, people of color were 61% more likely than white people to live in a county with a failing grade for either ozone, short-term particulate matter, or year-round particulate matter and 3.6 times more likely to live in a county with an F for all three. In this year's report, those numbers had jumped to 64% and 3.7 times respectively.

"Again this year, 'State of the Air' finds that the burden of living with unhealthy air is not shared equally."

"Again this year, 'State of the Air' finds that the burden of living with unhealthy air is not shared equally," the report authors wrote. "Although people of color are 41% of the overall population of the U.S., they are 54% of the nearly 120 million people living in counties with at least one failing grade. And in the counties with the worst air quality that get failing grades for all three pollution measures, 72% of the 18 million residents affected are people of color, compared to the 28% who are white."

Unequal exposure to air pollution is a persistent environmental justice problem in the U.S. A 2022 study, for example, found that urban neighborhoods that had been "redlined" in the 1930s were more likely to experience higher air pollution levels nearly a century later.

"Racism from the 1930s, and racist actions by people who are no longer alive, are still influencing inequality in air pollution exposure today," study co-author and University of Washington professor Julian Marshall said at the time.

"[A] changing climate is making it harder to protect human health."

In addition to persistent inequality, there is a new factor worsening air pollution for some U.S. residents: the climate crisis. While other markers of air pollution were down, the report found that the number of people living in counties that earned a failing grade for short-term spikes in particulate matter pollution rose to 63.7 million–the highest total in 10 years and half a million more than in last year's report. These spikes disproportionately impacted people in the Western U.S., where the climate crisis has led to a longer fire season of larger, more extreme blazes.

"Wildfires in the western U.S. are a major contributing factor to the increasing number of days and places with unhealthy levels of particle pollution," the report authors wrote. "They are also increasing the severity of pollution, resulting in a sharp rise in the number of days designated as either purple or maroon."

(Purple stands for "very unhealthy" according to the Air Quality Index, while maroon stands for "hazardous.")

All but two of the worst 25 cities for short-term particulate matter pollution were in the West, and three of the top five were in California–Bakersfield, Fresno-Madera-Hanford, Visalia, and San Jose-San Francisco-Oakland.

Given that California has robust clean air regulations, the cities' placement is evidence of how the climate crisis can reverse air quality gains. Another 2022 study found that wildfire smoke's contribution to daily particulate matter pollution in the West had, in 10 years, turned back the clock on regulation-based improvements amassed over decades.

"[A] changing climate is making it harder to protect human health," the ALA report authors wrote. "The three years covered by 'State of the Air' 2023 ranked among the seven hottest years on record globally. High ozone days and spikes in particle pollution related to 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."

While the climate crisis means regulators need to work harder, it's not a reason to give up on political solutions for air pollution. ALA recommended several steps the Biden administration could take, including finalizing tough standards for tailpipe emissions from Model Year 2027, reducing pollution from the oil and gas industry and fossil-fueled power plants, and tightening air pollution standards to eight micrograms per cubic meter annually and 25 micrograms per cubic meter daily for particulate matter and 60 parts per billion for ozone.

"The Biden administration is behind on its clean air to-do list and must urgently pick up the pace by moving on key clean air regulatory priorities," the report authors wrote.