How does air pollution affect physical performance?— published: 05-04-2012
Inhalation of major air pollutants has been found to decrease lung function and exacerbate symptoms of exercise-induced bronchospasms, including coughing, wheezing, and shortness of breath. In order to meet oxygen demands during light- to moderate-intensity exercise, you take in more air with each breath. And when you breathe through your mouth, you bypass the nose’s natural filtration of large particles and soluble vapors. As your exercise intensity increases, you breathe faster and deeper, which also increases the amount of pollution inhaled and the depth it travels into your respiratory system.
If you live in or near a busy city, you are exposed to even more combustion-related pollutants—such as nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), and ozone—that can inflame your airways and worsen asthmatic responses. Exposure to freshly generated emissions is most common near areas of high vehicular traffic.
While indoor exercise is often a good alternative to limit exposure to outdoor pollutants, some indoor conditions may be just as toxic. Nitrogen dioxide (NO2)—the more toxic NOx—is usually higher in gas-heated homes and indoor areas with poor ventilation. Carbon monoxide poisoning is also more likely to occur indoors. When carbon monoxide is in your system, the blood carries substantially less oxygen, reducing performance and eventually leading to carbon monoxide poisoning. Be sure to choose well-ventilated areas for indoor exercise.
Particulate matter and ozone are two significant pollutants you may be exposed to outdoors. Inhalation of high levels of particulates has been shown to reduce exercise performance as much as 24.4% during short-term, high-intensity cycling. Women may be more vulnerable than men to certain particulates, associated with greater decrements in performance. Ultrafine particle concentrations are highest in freshly generated automobile exhaust, and these small particles can be carried deep into the lungs. However, the further away you are from fresh exhaust, the less concentrated the particulates.
Bad ozone occurs lower in the atmosphere; it is not directly emitted into the air but is created from chemical reactions between NOx, volatile organic compounds (VOCs), heat, and sunlight. Ozone levels also are higher in summer than in winter; and especially in larger, hotter cities, concentrations tend to peak around midday when solar radiation is highest. Exposure to ozone during exercise has been found to increase resting blood pressure, reduce lung function, and decrease exercise capacity.
The risks associated with not exercising at all are far greater than the risks of exercising outdoors; it just takes a little more planning on days and in conditions when pollution is bad. When planning outdoor exercise activities, follow these tips to limit your exposure to pollutants:
- Avoid exercising in areas of heavy traffic, such as along highways and during rush hour.
- During summer, exercise earlier in the morning, when ozone levels and temperatures are not as high.
- Check the domestic or international air-quality ratings to determine if it’s safe to exercise outside. Limit your time outside on Code Red and Code Orange days. Environmental conditions on these days are not healthy, especially for children, the elderly, and people with existing respiratory conditions.
- Exercise indoors when the air quality indicates high ozone and particulate levels.
- Before any demanding physical activity, limit your carbon monoxide exposure by avoiding smoky areas and long car rides in congested traffic.