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Should I Worry About Air Pollution While Training?

How to adjust training for smog and wildfire smoke.

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Science has proven two statements as fact: Exercise is good for you; air pollution, not so much. So what happens when the two statements intersect–say, when a long run is scheduled to take place during a smog advisory?

Air pollution is made up of a mix of gases (like ozone, carbon monoxide and oxides of nitrogen) and particles of various sizes. It can come from industrial sources such as coal-fired power plants, internal combustion engines such as cars, and from natural sources like forest fires. It’s nasty stuff–the World Health Organization estimates 7 million people die prematurely each year because of exposure to air pollution.

“Air pollution is bad for you,” says Michael Koehle, MD, PhD, of the University of British Columbia. “People who live in areas of increased air pollution are going to have more health problems as a result of it. On high pollution days, there are more hospital admissions for respiratory and cardiovascular problems.”

So if simply breathing in polluted air is a bad thing, surely huffing and puffing it during a long run is a bad idea–right? Not quite, says Koehle.

“Working out in poor air quality is worse than in clean air. We should avoid it as much as possible. However, the downsides of not exercising at all are worse. We know that in areas of higher pollution the active people have fewer health problems than the sedentary people, so in general we need to stay active.”

This is backed up by a 2015 University of Copenhagen Study, which found that the benefits of exercise prevail over the potential hazards from air pollution. Exercise is a critical component for health, even when the surrounding environment is not-so-healthy.

That doesn’t necessarily mean you should head out in the midst of the smoggiest day or run in smoky conditions. Just as we check the weather before we head out the door, so too should we check air quality (In the United States, Koehele suggests the Environmental Protection Agency’s AirNow app to find local air quality forecasts.) Green and yellow forecasts (“good” and “moderate” air quality, respectively) mean you’re good to go. An orange forecast means proceed with caution, especially if you have asthma or allergies. On days with the most extreme pollution (red or purple designations), workouts should be taken indoors or rescheduled.

Other suggestions for mitigating the effects of air pollution:

1. Run early in the day, when air quality tends to be better. Sunlight amplifies air pollution.

2. If you cannot or will not take your workout indoors during times of high pollution, consider reducing the intensity and/or duration.

3. A respirator mask with particulate filters can be effective at filtering out air pollution, so long as it has the word “NIOSH” and either “N95” or “P100” printed on it. However, it’s important to note these masks can make breathing challenging during a run or bike ride.

4. After a training session outside, clean nostrils with a neti pot to remove residue.

5. Athletes with exercise-induced asthma may find their prescription inhaler does not work as well (or at all) for attacks caused or exacerbated by air pollution. Such athletes should consult with their doctor to adjust their treatment plan as needed.

6. Any athlete having excessive issues (i.e., shortness of breath on exertion), should end the exercise session immediately and see a doctor.