How does pollution affect exercise?
In a study from the University of North Carolina-Chapel Hill, 17 college students did a stationary bike workout inside a room that contained noxious gases similar to what you’d see in a polluted city.
After breathing in these fumes for just 10 minutes, the athletes’ blood pressure had increased, and their arteries became constricted.
Exercise is supposed to deliver oxygen and nutrients to your muscles and help your vessels expand, but when they can’t do this, it causes problems with recovery after exercise.
Did the pollution hurt their athletic performance?
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Not on an acute level—in other words, no one got off their bike panting from respiratory distress. But there was another test where 16 elite cyclists stayed overnight in this nasty chamber, which has the gases and is filled with fine particles of all sorts.
There were 20 million particles per meter cubed—that’s like sitting under a highway overpass on the worst air quality day. They did this for three nights in a row.
How did that affect their performance?
On the fourth day, they had to do an endurance ride where they worked at 80 percent of their VO2 max until exhaustion—on average, about 1 hour and 40 minutes. The athletes went out onto the track, and four didn’t finish (two dropped out due to cardiovascular problems, one got nauseous, another had difficulty breathing).
Most people thought about quitting around 2 or 3 hours into it! That shows you how much pollution affects athletic performance.
Did the athletes experience any long-term health problems?
We don’t know yet. The next step is to repeat this experiment for 20 nights in a row, which will allow us to see how quickly you recover after exposure to pollution and if that affects changes over time.
We’ll also look at the effects of pollution on inflammation, heart rate variability, lung function—all sorts of things typically affected by exercise.
You’re working with the South African Olympic committee now—are they interested in your findings?
Yes, I think they’re very interested because it’s such a big problem there. It’s not just elite athletes either; we see these across all levels of performance down there, even in recreational athletes.
There are respiratory issues linked to the pollution that can be clinically significant and affect recovery time between workouts.
What advice does this study give you?
It’s important for people exercising outside of the lab to realize they’re putting themselves at risk, especially if they have pre-existing conditions. It might not show up right away, but over time it could cause problems with their cardiovascular system or vascular function, depending on what type of pollutant is in your environment—which varies greatly depending on where you live.
Even since these experiments were done, China has had terrible air quality days due to forest fires that spread across Russia into eastern Asia this summer. We’ve already seen some evidence that these types of conditions do influence athletic performance.
How polluted does it have to be for your performance to suffer?
It’s hard to say because people are exposed to different levels in the real world. I think it’d take a lot less in China—we can see even minimal exposure compromising performance. But if you live in a city where the pollution is typically lower, you might not notice much of a difference until you get up into substantially higher levels.
You could still be at risk, too, though—there’s no threshold below which it would be safe for an athlete.
In my hometown of Seattle, we’re known as being one of the most polluted cities in America—do our athletes need to worry about this?
Yes, they might need to worry about it depending on their training. In Seattle, you have a lot of these particles from wildfire smoke and elevated ozone levels due to car pollution. But it doesn’t matter where you live—it’s about the number of pollutants in the environment and how long you’re exposed to them.
People think they can protect themselves by wearing masks or staying indoors, but this is a myth—in our experiments, we found that workers on a break had higher concentrations inside their acts than outside of them!
We also saw people working inside with windows closed all day still had high exposures because the pollutants had built up inside. You can’t protect yourself by staying indoors, either—most buildings don’t have air filters that are good enough to keep out ultrafine particulate matter, which is what causes the most significant problems.
You also can’t tell how polluted it is by looking outside—the best thing you can do is check the air quality index online or via a mobile app.
Any final words of advice?
People need to pay attention to their environment and consider pollution when training. It’s not about running inside on a treadmill instead—it’s about reducing long-term exposure and staying healthy in general.
Exercise can be beneficial, but some things come with it that people need to be aware of and don’t fully understand yet. Knowing more will help us figure out how we might best protect athletes from getting the most out of their workouts while avoiding unnecessary health risks from things like pollution.