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How Air Pollution Affects Runners

From wildfires to car traffic, all runners should be aware of the air quality before working up a sweat.

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

On the 50th anniversary of the Clean Air Act, in 2020, the “State of the Air” report was released and found that Bangor, Maine; Burlington, Vermont; Honolulu, Hawaii; and Wilmington, North Carolina had the lowest levels of air pollution in the United States. Which leaves those of us living elsewhere thinking: “I’ll breathe what they’re breathing.” 

Because meanwhile, half of the nation’s population is living with and breathing polluted air. 

Of the 25 most polluted cities, 24 were located in the western part of the United States where wildfires dominate the tail-end of summer. 

It’s easy to think about air quality when you look at the window to see an ashy, hazy sky. Seeing a film of ash on your doormat might have you wondering, “Should I be running in this?” 

But even on presumably clear days or in areas far away from fire—you should be considering what you’re inhaling, especially if you are running outdoors. 

A brand new study published in the European Heart Journal looked at over one million active adults aged 20 to 39—the first study of its kind to look at the effects of air pollution and physical activity on young adults. Looking specifically at the risk for cardiovascular disease, they found that being exposed to high levels of pollution while exercising vigorously negatively impacted cardiovascular health. 

In most instances, a lack of physical exercise can increase your risk of heart disease. That was still the case if the participant was only exposed to low to moderate levels of pollution, but as pollution levels increased the more risky exercising became. 


And that begs the question, when is running outdoors safe and when is it going to do more harm than good? We probed experts to help you take your health into your own hands. Here’s all about what’s up in the air—and what you can do about it.

What Are the Health Effects of Air Pollution?

What, exactly, is hitting your lungs when you go for a run? “Air pollution is like a recipe that varies by location, weather, season, and time of day,” says Michael Koehle, the head of University of British Columbia’s Environmental Physiology Lab and a leading expert on exercise and air pollution. “The recipe includes a mixture of various gases, like carbon monoxide or smog, and particles like dust and pollen.” 

Diesel exhaust, for example, can trigger asthma. Other pollutants, like ozone (a key component of smog), can be harmful to the cardiovascular system and can even cause cancer. “The lungs are taking the air we breathe and transferring it on to our blood cells, which immediately goes to the heart to be pumped to the rest of the body,” says Jason Way, a naturopathic doctor. “Over a prolonged period of time, smog can decrease your ability to run at your full capacity.”

Wildfire smoke can cause some of the same issues as other pollutants because it is made up of particulate matter, carbon dioxide, hydrocarbons, and other chemicals and minerals. Although, according to the California Department of Public Health and the California Air Resources Board’s Wildfire Smoke Guide, the long-term health effects of cumulative exposure from multiple seasons hasn’t been studied enough to make definitive health claims. 

“We do know that when the air quality is bad, people with respiratory disease such as asthma are more likely to use their medications and have symptoms that make them seek health care. It can result in increased visits to the emergency department and being hospitalized,” says Dr. Colleen Reid, assistant professor of geography at the University of Colorado, who researches the health effects of exposure to air pollution and wildfires. “There is also some evidence that people with heart disease may also be affected.”

Exercising outdoors in areas with increased air pollution is not advised, according to the World Health Organization, because the increased respiration also increases the amount of harmful particles coming into your lungs. 

Pollution can undo some of the benefits of exercise, like reducing cardiovascular health as the European Heart Journal study found. Beyond that, some studies (like one cited by Oiselle Volee team member Taisa Kushner, Ph.D., in this very informative Twitter thread) show that the benefits aerobic exercise can have on brain health and function are inhibited when people exercise outdoors in polluted areas.

And what about the masks we’ve been wearing to keep each other safe from spreading COVID-19? Dr. Reid explains that while the cloth and surgical masks are effective in slowing the spread of the virus because they catch many of the droplets we exhale, they’re not very effective in protecting us from the air we breathe, “and therefore do not help protect the wearer from the tiny particles in the air.”

4 Ways to Minimize Your Exposure to Air Pollution

While all the evidence (and the sky) looks bleak, it’s not to say you must stick to indoor treadmill runs forever-more, especially if you’ve re-evaluated that option during the pandemic. And for socioeconomic reasons it may not be possible to simply stay inside during a particularly bad episode. These expert tips can help you get out for your run in a safer way.

Check the air quality before you head out.

AirNow provides air quality data in partnership with the Environmental Protection Agency, National Oceanic and Atmospheric Administration, National Parks Service, NASA, the Centers for Disease Control and Prevention, and tribal, state, and local agencies. Visit their site to check the outdoor air quality index (AQI) in your area before you head out. If the AQI measures more than 150 (100 if you have asthma or other breathing issues), hit the gym or be extra alert for any symptoms like shortness of breath, coughing, or throat irritation while you run.


Another similar option is the Smoke Sense App or AirVisual. Dr. Reid explains that AQI may differ between apps and websites, depending on the monitoring systems and how they choose to calculate the exact AQI number. “But you can use the AQI category to give you a sense of whether the air quality is good for a run,” she says. If it’s listed as “Good” or “Moderate,” it’s probably safe for a run, while “Unhealthy,” “Very Unhealthy,” or “Hazardous” are probably better to hold off on.

Time your run just right.

Koehle says it’s key to be aware of when you run outside to be sure you’re breathing in the best air. “Pollution levels are higher during rush hour and in the heat of the day, so it’s better to go out early or in the late evening,” he says. Ground level ozone is the result of a chemical reaction between pollutants and sunlight, which means that it will be at its worst if you try hitting the pavement in the middle of the afternoon when the sun is strongest.

Run in greener spaces. 

Some studies show that you may breathe in 100 times more pollutants running within a mile of the highway than you would in a more rural area. Avoid congested areas if you can, and run in a park or a quieter neighborhood with tree coverage whenever possible. Minimize your time near busy roads since pollution drops significantly once you’re as little as 200 yards away from the congestion. Or dedicate high pollution days to a fresh air trail run.

Eat foods that fight off toxins. 

Loading up on foods rich in antioxidants can help your body eliminate toxins picked up from pollution, Way says. Try adding more leafy greens, broccoli, tomatoes, bell peppers, oranges, berries, nuts, and seeds, and drink plenty of water.