Physical activity is one of the most important pillars for maintaining good health. However, a new study published in the journal BMC Medicine warns that its protective benefits begin to diminish as air pollution levels increase in neighborhoods.
Benefits that fade in polluted environments
Those who exercise frequently have a lower risk of death overall, but prolonged exposure to high levels of air pollution can reduce that protection over time, especially against cancer and cardiovascular diseases.
The study results indicate that physical activity remains beneficial even in polluted areas, although improving air quality could maximize those benefits.
“Our study shows that toxic air can, to some extent, block the benefits of exercise, although it does not eliminate them,” explained Andrew Steptoe, professor of psychology and epidemiology at University College London (UCL).
The analysis of more than 1.5 million adults
Steptoe’s team analyzed data from more than 1.5 million adults followed for over ten years in countries such as the United Kingdom, Denmark, the United States, Taiwan, and China.
The focus was on fine particles PM2.5, a type of pollution that comes from burning coal and fossil fuels, vehicle emissions, waste burning, and other sources. These particles are so tiny that they can cross the blood-brain barrier and directly affect the heart and lungs.
Exercise and mortality risk
The findings show that:
- Those who practiced at least 2.5 hours of moderate or vigorous exercise per week had a 30% lower chance of dying than those who exercised less.
- In areas with pollution above 25 μg/m³, the risk reduction dropped to 12–15%.
- With levels above 35 μg/m³, the protective effects diminished even more. This threshold affects 36% of the world’s population.
Risks associated with air pollution
Other studies have linked air pollution to:
- Respiratory diseases.
- Cardiovascular problems.
- Neurological disorders such as Parkinson’s and dementia.
Recommendations for exercising in polluted areas
The researchers emphasize that they do not intend to discourage people from exercising outdoors.
“Checking air quality, choosing cleaner routes, or reducing intensity on polluted days can help maximize benefits,” noted Paola Zaninotto, professor of medical and social statistics at UCL.
Study limitations
The analysis was mainly conducted in wealthy countries, which could limit the applicability of the results in lower-income regions, where pollution is often higher. Additionally, data on indoor air quality and participants’ diets were not included, factors that also influence health.
Nevertheless, the conclusions held even after considering variables such as income, education, smoking, and health status.
Clean air and exercise for healthy aging
The researchers state that the results support efforts to improve air quality worldwide.
“We believe that clean air and physical activity are important for healthy aging, which is why we urge redoubling efforts to curb pollution levels that harm health,” concluded Steptoe.
