Right around the time when the days start getting longer and temps begin to rise, it's normal to want to ditch your spin class and liberate the road bike that's been sitting idle in your garage. What's not to love about filling your lungs with fresh spring air?
Actually, there is something. If your favorite bike path winds along a busy thoroughfare, or the tennis court you frequent is located near a traffic-clogged intersection, you may be loading your lungs with harmful pollutants in the form of ozone (the main component of smog) and microscopic bits of soot, dust, aerosol, metal, free radicals, and other airborne contaminants. Not only does this toxic assault on your lungs compromise the effectiveness of your workouts, but it can also take a toll on your health.
Running on Fumes
First, some good news. The air we breathe has become a lot cleaner in the past 30 years. Since 1980, emissions of the six worst pollutants have dropped by nearly 50 percent, thanks to stricter laws regulating air quality. But here's the thing: People who exercise outdoors may still breathe in up to 10 times more airborne nastiness than those who spend less time being active outside. Whether your workout of choice is running, cycling, or taking boot-camp classes on the beach, doing any kind of vigorous outdoor exercise that causes you to breathe hard means you are gulping more air than if you were standing still, says Sam Callan, USA Cycling's sport science and coaching education manager. Even moderate exercise, such as a brisk walk, can increase the amount of air you inhale. And along with all that extra muscle-fueling oxygen comes supersize portions of unhealthy pollution.
What's worse, as you huff and puff through your mouth, some of that contamination whooshes deep into your lungs, bypassing your nasal passages, the body's natural air filter. The result? An irritated and inflamed trachea and lungs. You may wind up with symptoms such as a pesky cough, chest tightness, or a scratchy throat.
Over time, regular exposure to pollution may trigger exercise-induced asthma (an attack of wheezing and airway constriction during a workout) and ups your risk for lung cancer by 20 percent, the same as a nonsmoker living with a smoker, says George D. Thurston, Sc.D., a professor of environmental medicine at New York University School of Medicine. Joggers who regularly run in high-ozone conditions may experience a thickening of the lining of their lungs (typically a smoker's affliction), which may prematurely age the lungs, although the exact health consequences are unknown, says Daniel Greenbaum, president of the Health Effects Institute, a Boston nonprofit organization that studies pollution's impact on health.
Yet these effects often go unnoticed. In fact, the fitter you are, the less likely you are to see signs. "Healthy people can be affected by air pollution without experiencing symptoms," says Norman Edelman, M.D., chief medical officer of the American Lung Association. So even if you feel fine, your lungs and workout still take a hit.
In a 2008 study, cyclists pedaled in polluted conditions. Three days later, the distance they could ride decreased by 5 percent. And women, who have smaller airways, are more affected by the irritation and swelling that restricts oxygen intake than men are. A 2010 study of marathon runners published in Medicine & Science in Sports & Exercise found that higher rates of pollution slowed women's race times, while men were unaffected.
Your Body on Bad Air
Pollution affects more than just your airways, says former air pollution scientist Kenneth Rundell, Ph.D. When you inhale airborne contaminants, your body launches a defense against "foreign invaders," which then causes inflammation. Over time, chronic inflammation can wreak havoc on every organ system. So it's not surprising that long-term exposure to bad air has been linked to a host of health problems—ironically the very conditions that regular exercise helps prevent—including high blood pressure, heart attack, stroke, type 2 diabetes, decreased immune function, and certain cancers. One Canadian research team mapped levels of traffic-related air pollution in Montreal against breast-cancer diagnoses. They found that women living in locations with the worst air pollution were almost twice as likely to develop breast cancer as those in the cleanest areas, says Mark S. Goldberg, Ph.D., one of the researchers and a professor in the department of medicine at McGill University.
If all this makes you want to strap on a gas mask every time you head outside, take comfort in this: Your lungs have several built-in cellular cleaning mechanisms that help neutralize irritants and rid the body of them, so you'll most likely recover pretty quickly from an occasional dose of dirty air.
The bigger concern is what happens after years of repeated exposure. In fact, the Environmental Protection Agency likens breathing high levels of ozone to getting sunburned. Do it once or twice and you'll be OK; do it all the time and you could wind up with permanent damage.
That's not to say you should retreat to the gym forever. "No one in their right mind would say never exercise outdoors," says Greenbaum. "There are so many physical and mental benefits." Even small amounts of sunlight boost blood levels of vitamin D (a critical nutrient related to bone strength, immune function, and yes, lung health). Natural terrain challenges your muscles and balance better than any gym machine. And being outdoors is a proven mood booster. One study found that even recalling outdoor exercise can improve your outlook. You just need to be safe about exercising outside. "Everyone should try to minimize their exposure as much as reasonably possible," says Edelman. Breathe easier with these strategies:
Get moving in the morning.
Ozone is generally lowest at this time, from roughly 6 a.m until 10 a.m., and it rises throughout the day as sunlight breaks down the hydrocarbons of auto exhaust, turning it into smog.
Replot your route.
Find ways around the busiest thoroughfares. A street with traffic that zooms past will be less polluted than a congested road that has cars idling at stoplights, their emissions hanging in the air. If you can't avoid high-traffic roadways, plan your workout so your hardest effort comes at the least congested part of your route. If you live in a city, hit the park.
Avoid the worst offenders.
Stay away from high-pollution scenarios altogether, such as parking lots and marinas with idling diesel vehicles (trucks, buses, boats) and areas where a forest fire is burning nearby. Yard equipment such as lawn mowers and snow or leaf blowers also spew fumes you don't want to inhale, so try not to be downwind of them, says Thurston.
Embrace the breeze.
"The worst pollution days are usually the hot, stale days of summer," says Greenbaum. Windy conditions often make for better air days because the breeze disperses pollution, reducing its concentration.
Eat your antioxidants.
Getting the recommended daily dose (75 milligrams) of vitamin C, particularly through foods (e.g., broccoli, spinach, oranges, and tomatoes), may help your lungs resist pollution-related damage, says Thurston. Vitamin C reduces free radicals, lowers the production of inflammatory histamines, and helps boost glutathione, a detoxifying agent that aids cells in dealing with carcinogens and heavy metals such as lead and mercury.
At your annual physical, ask your doctor to assess your lung function using spirometry, a test in which you'll blow into a measuring device. What to watch for: "A trend over time indicating any adverse changes from your previous visit," says Thurston. Remember, exercise is still the best way to keep your lungs flexible and in top shape.