Is it Safe to Exercise Indoors or Outdoors When Air Quality Is Bad? Here's What Experts Say

Neither situation is ideal, but one may be a bit safer than the other.

For days, three US cities have been listed as having the worst air quality in the world. Portland, Seattle, and Denver are among the 10 worst cities for air quality, according to world air quality monitoring agency, IQAir. It's all due to historic wildfires that continue to burn in parts of California, Oregon, and Washington.

Air quality in several other areas out west is listed as "hazardous" or "very unhealthy," and has been for days, per data from government-managed air quality organization AirNow.

If you live in one of these areas, but you're not under immediate threat of wildfire reaching your home, it's only natural to wonder what this means for your day-to-day life, including your workout routine. And, even if you don't live in one of those areas, you may still live somewhere that experiences poor air quality from time to time.

It all begs the question: Is it safe to exercise outdoors when air quality is bad? What about exercising indoors when the air quality is poor outside? And what can happen if you actually do it? Here's what pulmonologists and critical care experts have to say about exercising outdoors—and indoors—when air quality is bad.

Why is poor air quality so bad for you?

First, some air pollution basics: Air pollution is a pretty broad term to describe a mix of hazardous substances from both human-made and natural sources, per the National Institute of Environmental Health Sciences (NIEHS). There are a lot of things that can contribute to poor air quality, NIEHS says, including vehicle emissions, fuel oils and natural gas used to heat homes, byproducts of manufacturing and power generation, fumes from chemical production, smoke from wildfires, gases from volcanic eruptions, and gases like methane, that are emitted from decomposing organic matter in soils.

There are a lot of different elements in air pollution that are bad for you, but they generally include ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter, chemicals like sulfates, nitrates, carbon, or mineral dusts that are 30 times thinner than a human hair, NIEHS says.

There's a lot to worry about there, but it's all important—fine particulate matter can be inhaled deep into your lung tissue, where it can lead to serious health issues over time. "Fine particulate matter has the potential to reach all the way to alveoli, or tiny air sac, of your lungs, which is where oxygen and carbon dioxide are exchanged," Raymond Casciari, MD, a pulmonologist at St. Joseph Hospital in Orange, Calif., tells Health. "That's where it goes from air to blood. We definitely don't want fine particulate matter there."

On a short-term basis, breathing in poor-quality air can cause symptoms like coughing, trouble breathing normally, stinging eyes, a runny nose, wheezing, chest pain, and shortness of breath, Dr. Casciari says. But over time, being exposed to air pollution can lead to serious health issues. The NIEHS specifically lists the following as potential issues:

  • An increased risk of lung disease, including asthma, emphysema, and chronic obstructive pulmonary disease (COPD)
  • Chronic bronchitis
  • Impaired blood vessel function
  • Increased risk of stroke
  • Hypertensive disorders
  • An increased risk of cancer, including lung and breast cancer

So, is it safe to exercise outdoors when air quality is bad?

That's a hard no. Being exposed to poor air quality under any circumstances isn't great, but exercising in it exposes your respiratory system to even more of that bad air, pulmonary critical care expert Reynold Panettieri, MD, director of the Institute for Translational Medicine and Science at Rutgers University, tells Health.

"When you exercise, you breathe in and out faster, and that gives more of a likelihood of exposing greater parts of your lung to air pollution," he says. You're also breathing more deeply when you exercise, and that can push pollutants deeper into your lungs, Dr. Panettieri says. "In bad air quality, the worst thing you can do is exercise."

There's also, unfortunately, no way to get around the dangers of exercising in poor air quality. Wearing a cloth face mask, for example, won't do much to protect you. While it can help filter out larger particles in the air, it won't block fine particulate matter from getting into your lungs, Dr. Casciari says.

And even if you do attempt to work out outdoors—which, again, you shouldn't do—your performance will suffer. You won't be able to work out as well in poor air quality, Dr. Panettieri says. Overall, it's just not a good idea under any circumstances. "When the air quality is bad, you can wait a day or two to exercise outside," Dr. Casciari says. "It's not worth it."

OK, what about exercising indoors when air quality is bad?

If you can't get outside and exercise in poor air quality, you still have the option to work out inside, right? It depends. "Certainly, depending on how homes are ventilated [and] how 'tight' they are, some particulate matter can get into the home," Louis R. DePalo, MD, professor of pulmonary medicine and critical care medicine at the Icahn School of Medicine, tells Health. That can lead to some symptoms of air pollution exposure, particularly if you have asthma or another lung condition, he says, "but certainly on a decreased scale. "

"Exercising inside is significantly less risky, but still can cause respiratory symptoms if the smoke levels are high," Jonathan Parsons, MD, a pulmonologist at The Ohio State University Wexner Medical Center, tells Health. If you want to exercise indoors when the air quality is bad, Dr. Casciari recommends making sure all of your doors and windows are closed, keeping the air filter in your air conditioner (if you have it) clean, setting your air conditioner to recirculate, and doing your best to avoid contributing to indoor air pollution by taking a pass on doing things like frying foods and burning candles.

It's also not a bad idea to limit how long you work out inside, especially if you're doing something with a lot of aerobic demands, Dr. Parsons says. If you can, it's also a good idea to run an air purifier in the room where you're working out This can help get rid of any particles that may have worked their way into your home, Dr. Casciari says.

And if you do decide to exercise indoors during poor air quality, above all, it's crucial to listen to your body. Dr. DePalo recommends being on the lookout for symptoms like shortness of breath, wheezing, coughing, and chest pain—these are all signs you really should stop and wait until conditions are better.

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