Air Quality Is Improving Nationwide, but One Type of Harmful Pollution Remains a Threat

wildfire haze in california
Mario Tama / Getty Images.

Key Takeaways

  • Fewer Americans are living in counties with failing air pollution grades, thanks to falling rates of ozone pollution.
  • But there has been an increase in fine particle pollution, particularly in Western states.
  • Particle pollution can cause severe short- and long-term health effects, including lung cancer and heart disease.

Air quality is improving nationwide, but more than a third of Americans still live in places with unhealthy levels of air pollution, according to a new report from the American Lung Association (ALA).

Since the Clean Air Act established limits on six major outdoor air pollutants in 1970, air pollution emissions have fallen by 78%, according to Environmental Protection Agency (EPA).

The ALA used the EPA’s Air Quality System to track the two biggest sources of air pollution—ground-level ozone and fine particle pollution. Ozone is a caustic gas that can cause inflammation and damage to tissues and DNA throughout the body.

While ozone pollution has improved, particle pollution is a worsening health threat for certain populations, particularly among residents in western states and communities of color.

Tiny particles from wildfire smoke, vehicle emissions, and agricultural dust can wreak havoc on the body. Short-term spikes in particle pollution trigger asthma attacks, heart attacks, and strokes, while long-term exposure is linked to lung cancer, heart disease, and COPD.

“The improvements that we do see being made in air quality aren’t equally distributed. There are major differences in exposure to unhealthy levels of air pollution between eastern and western states and between people of color and White people,” Katherine Pruitt, lead author of the report and national senior director for policy at the American Lung Association, told Verywell.

David Hill, MD

Our industrial zones and our neighborhoods are planned so that the downwind neighborhoods tend to be poor neighborhoods and communities of color. All those populations end up being at higher risk to suffer these pollutants.

— David Hill, MD

Air Quality Isn’t Evenly Distributed

For decades, eastern cities had the dirtiest air. But air quality in these cities has improved as they’ve cleaned up “old pollution” in recent years, Pruitt said, such as power plants, factories, and highways.

In 2004, fewer than half of the counties with failing grades for daily spikes in particle pollution were west of the Rockies. Now, of the 111 counties with unhealthy spikes, all but eight are out West. While 20 of the 22 states with failing grades for year-round particle pollution were east of the Rockies in 2004, all 17 failing counties are in the West this year.

“Everyone is equally benefited from the progress that we’re making through policy change and systems change. But there are other factors at work in the West that are making cleanup harder or are setting them back,” Pruitt said.

Pruitt chalks this up to the abundance of wildfires and droughts that plague the West. While California has “always been at the forefront” of controlling pollution, Pruitt said the state’s massive population, propensity for wildfires, and large networks of shipping ports and railroads work against it.

Population growth across the Sun Belt and an increase in oil and gas extraction, especially fracking, have also contributed to the pollution shift.

Pruitt said the ALA’s grades for Western air pollution are stricter than the standard air regulations. The EPA’s regulatory standards don’t account for “exceptional events” when counting the number of bad air days in a locality. For instance, a wildfire wouldn’t be counted because such environmental events are largely out of a government’s control.

“The Lung Association in the State of the Air report doesn’t have to worry about whether or not states can attain the standard,” Pruitt said. “Our job is to tell the public the quality of the air they’re breathing, so we don’t throw out any of that data. If it’s a bad air day, it’s a bad air day, and we want the public to know about it.”

More than half of the nearly 120 million people who live in areas with poor air quality, more than half are people of color. They are 3.7 times more likely to live in a county with a failing grade for all three measures, according to the report.

“Our highway traffic corridors are built primarily through lower-income communities. Our industrial zones and our neighborhoods are planned so that the downwind neighborhoods tend to be poor neighborhoods and communities of color,” said David Hill, MD, a pulmonary and critical care physician in Waterbury, Connecticut and chair of the public policy committee for the American Lung Association. “All those populations end up being at higher risk to suffer these pollutants.”

Fine Particle Matter Remains the Biggest Health Threat

Particle pollution can come from many sources, including power plant emissions, automobile exhaust, and dust from construction sites and fields. Wildfires are one of the greatest drivers of particle pollution in recent years.

The size of these fine particles (PM2.5), more than their composition, is what makes them so harmful. PM2.5 is about one-twentieth the width of a strand of human hair. These tiny particles can get lodged in the lungs and move into the bloodstream. From there, they can cause inflammation throughout the body.

Short-term exposure to PM2.5 can cause the most acute symptoms, like coughing, chest pressure, and asthma attacks. It can also trigger heart attacks and strokes. After years of exposure, people may develop cancers, lung disease, and heart disease.  

“Short-term spikes in particulates—just hours to days of that—have effects and cause premature death, respiratory illness, and cardiovascular disease all to worsen,” Hill said. “We're seeing more and more lung cancer in people who never smoke cigarettes. How much air pollution is playing a role in that is something that needs to be elucidated further.”

Wildfire smoke can be particularly damaging. A 2021 study on hospitalizations in California found that wildfire smoke was 10 times more harmful to human health than other pollution sources. Providers are still seeing the effects of those fires, as particles persist years later, said Reza Ronaghi, MD, an interventional pulmonologist at the University of California, Los Angeles Medical Center who is not affiliated with the report.

Young children, pregnant people, and older adults are particularly vulnerable to the effects of air pollution, Ronaghi said. Exposure to wildfire pollution can exacerbate health problems for people with pre-existing heart disease, lung disease, and diabetes.

David Hill, MD

The fewer toxins you breathe in, the better. It’s kind of like ‘How many cigarettes are safe to smoke?’ The probable answer is none.

— David Hill, MD

Further Cleaning the Air Starts with Industry and Climate Change

Much of the progress in cleaning up ozone pollution has come from closing coal-fired power plants, reducing tailpipe emissions, and cleaning up industrial smokestacks, Pruitt said.

Pruitt said there are opportunities to further clean the air and minimize pollution. The Inflation Reduction Act has made funds available to invest in environmental justice-focused projects.

“The Biden administration early on set themselves an ambitious clean air and climate change agenda. They’ve got a long to-do list of things that they're working on, and they are doing it more slowly than we would like to see,” Pruitt said.

Pruitt said she hopes to see stronger new emission standards for cars and trucks, and more efforts to electrify vehicle fleets. Stopping methane leaks from gas pipelines and setting pollution limits on oil and gas companies can further improve air quality.

Meanwhile, research indicates there are health harms to pollution exposure at levels lower than the current air quality standards set by the EPA. The report authors called on the EPA to strengthen the standards so the public can have a clearer understanding of how much air pollution can trigger health effects.

“The fewer toxins you breathe in, the better,” Hill said. “It’s kind of like ‘How many cigarettes are safe to smoke?’ The probable answer is none.”

While reducing emissions, Hill said it’s also important to address climate change. As areas of the country get hotter and drier, people are more likely to inhale fine particles from dust, smoke, and smog. While these effects are most visible in the West, pollution can travel across state lines and affect air across the country.

“Climate change is driving the forest fires, and driving the transition to deserts which creates more dust and particulate matter,” Hill said. “Climate change is a public health issue.”

How to Stay Safe on Poor Air Quality Days

“The first and most important thing to do is to protect yourself and your family from unhealthy exposure,” Pruitt said.

People can get a day-by-day forecast of air quality on the weather app on their phones or by checking, a site with data from multiple U.S. agencies.

“Knowing your air quality in your region is really important because these particles are not visible,” Ronaghi said. “Most days will look clear.”

Being aware of air quality can be particularly important for people who have a respiratory or heart condition, Ronaghi said.

On poor air quality days, people should be mindful of the time they spend outdoors. Exercising indoors or in the morning, when air quality tends to be better, can reduce one’s exposure to toxins. Exercising away from major roadways can also minimize pollutant inhalation.

Keeping the windows closed on poor air quality days and cooling off with air conditioning fitted with an air filter that can reduce exposure to toxins indoors, Ronaghi said.

People living in fire-prone or other high-pollution environments can create what Pruitt calls a “clean room” using air filtration devices and minimizing sources of indoor air pollution.

“If you’re on one of the unfortunate millions these days who are living in a fire-prone area, and are going through an extreme smoke event, then you really need to take precautions,” Pruitt said.

For instance, people with lung disease should pack a “go-bag” of medications, oxygen, and any other medical items they might need, she said. N95 respirators—the masks that became so popular during the COVID-19 pandemic—can also filter out fine particles.

“We’ve made a lot of progress, but there’s still a lot of work to do. And there are now opportunities to continue to do that work. If we all work together, we can continue to see the benefits for in people’s health from cleaning up the air,” Pruitt said.

What This Means For You

Even low levels of air pollution can have negative health consequences. You can track air quality changes on and find more information about how to protect yourself during spikes in pollution at the ALA’s site

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Lung Association. State of the Air 2023: Health Impact of Air Pollution.

  2. American Lung Association. State of the Air 2023: Key Findings.

  3. Environmental Protection Agency. Particle Matter (PM) Basics.

  4. American Lung Association. State of the Air 2023: Short-Term Particle Pollution Trends.

  5. Aguilera R, Corringham T, Gershunov A, Benmarhnia T. Wildfire smoke impacts respiratory health more than fine particles from other sources: observational evidence from Southern CaliforniaNat Commun. 2021;12(1):1493. doi:10.1038/s41467-021-21708-0

  6. American Lung Association. State of the Air 2023: Recommendations for Action.

Additional Reading

By Claire Bugos
Claire Bugos is a health and science reporter and writer and a 2020 National Association of Science Writers travel fellow.