Air pollution affects nearly all organs in the human body and is linked to chronic health conditions such as heart disease, respiratory issues, and cancer. According to the World Health Organization, 99% of the global population breathes in polluted air, resulting in 6.7 million premature deaths annually. Audrey de Nazelle, an associate professor at Imperial College London, notes that air pollution impacts not only respiratory health but also cardiovascular disease, diabetes, cognitive function, and reproductive health.
One major concern is PM 2.5, tiny particles measuring 2.5 micrometres across, released directly into the air from traffic. These particles can penetrate deep into lungs, cross into the bloodstream, and travel throughout the body. Research has found a link between PM 2.5 and an increased risk of Parkinson's disease. Haneen Khreis, an epidemiologist at the University of Cambridge, explains that these small particles can cross the blood-brain barrier, causing damage to vessels and the barrier.
Other pollutants, such as nitrogen dioxide, sulphur dioxide, ammonia, carbon monoxide, and ground-level ozone, also pose health risks. Nitrogen dioxide, for instance, can cause lung inflammation and impair lung development and function. Exercising along busy roads or in cities increases exposure to these pollutants. A 2025 review of 51 studies found a link between air pollution and an increased risk of Parkinson's disease.
Despite the risks, experts emphasize that the benefits of exercise often outweigh the harms of air pollution. A 2016 study found that the health gains of walking and cycling outweigh the harms of dirty air, except in exceptionally polluted areas. Exercise has been shown to reduce the risk of an early death, even in polluted environments. A recent review paper found that exercising in air-polluted environments was associated with a 26% reduction in mortality risk.
Individuals with preexisting health conditions, such as asthma or cardiovascular disease, should be more cautious when exercising in polluted areas. However, research has found that exercise still improves lung function and lowers blood pressure in polluted areas. It can also counteract some of the cognitive impacts of pollution. De Nazelle notes that exercising in cleaner air is preferable, but exercising in polluted areas is still beneficial.
To minimize exposure to air pollution, experts recommend finding the greenest or least congested areas for exercise. Moving one or two streets away from heavy traffic can slash pollution exposure by 20% to 30%. Opting for side streets instead of busy routes can cut exposure by 50%. Avoiding rush hour and peaks of ozone during hot sunny afternoons can also help reduce exposure.
Monitoring local air quality pollution indexes can also help individuals make informed decisions about exercising outdoors. On days with higher air pollution, exercising indoors or in parks may be a better option. By taking these precautions, individuals can minimize their exposure to air pollution and enjoy the benefits of exercise while reducing potential health risks.
Key points
- Exercising in polluted urban environments poses health risks, but benefits often outweigh harms.
- Finding greenest or least congested areas for exercise can minimize exposure to air pollution.
- Monitoring local air quality pollution indexes can help individuals make informed decisions about exercising outdoors.
