You might not give much thought to the exhaust fumes from passing cars, emissions from local industries or agricultural pollutants during your morning walk, but exposure to pollution can take its toll on your health.
A World Health Organization report notes that ambient air pollution contributed to more than 5% of deaths worldwide, including deaths from lung cancer, stroke and chronic obstructive pulmonary disease (COPD). Research published in The Lancet found the negative effects of toxic air pollution in cities could override the benefits to your heart and lungs that come from exercise.
Researchers followed 135 participants aged 60 and older to assess the effects of walking on busy streets with high levels of pollution on the heart and lungs. The participants were divided into two groups: One group had stable ischemic heart disease or COPD and the other had no health issues. In all groups, short-term exposure to traffic pollution was associated with decreased lung function.
According to researcher Kian Fan Chung, a professor of medicine at the National Heart and Lung Institute at Imperial College London, the effects were significant enough to cancel out the cardiovascular benefits of walking.
“How these are canceled remains to be explained [but] we presume that it may result from the effects of these pollutants like fine particles or gases such as [nitrogen oxide] in inducing oxidative stress acting on the airways or blood vessels,” Chung explains. “We have not tested more vigorous exercise than walking but suspect that our observation might also apply there, too.”
In the study, healthy recreationally trained cyclists were exposed to high concentrations of diesel exhaust before a ride. Although exposure to diesel exhaust before a time trial didn’t impact performance, it was linked to lowered lung function and increased exercise heart rate.
“Exposure to [pollution] can increase chest tightness, wheezing and shortness of breath and … may increase the perception of effort, which may cause individuals to slow down to terminate exercise prematurely,” explains researcher Luisa Giles, PhD, instructor in the sports science department at Douglas College.
It’s not great news but it doesn’t mean you should give up on outdoor workouts. In fact, Giles notes, “Staying fit and healthy will minimize the health impacts of air pollution, so continue to exercise regularly and eat a healthy diet.”
Here are three ways to keep pollution from sidelining your workouts:
Check the Air Quality Index
The AQI measures five major air pollutants: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide and nitrogen dioxide and assigns levels from 0–500; lower numbers mean better air quality. Giles suggests shortening, postponing or relocating workouts when the numbers hit 101 or higher to minimize exposure to pollution. “If you are healthy and have to exercise, stop if you notice any symptoms [like chest tightness or shortness of breath,” she says.
Schedule morning workouts
Ozone levels often peak in the afternoon to early evening, according to the U.S. Environmental Protection Agency. Walking first thing in the morning. Lacing up your sneakers or hopping on your bike before rush hour when carbon monoxide levels will be lower, especially in urban areas, is best.
Head to a local park
The further you are from the city, the cleaner the air. It takes a bit of extra effort to commute to a park or nature trail but Chung notes, “It would be worth it in the long term for getting the health benefits of walking exercise.”
If getting out of the city isn’t an option, choose side streets over major thoroughfares.