Air Pollution Undermines Health Benefits Of Exercise, Evidence Says | Health

MONDAY, Dec. 8, 2025 (HealthDay News) — Air pollution can undermine some of the health benefits active folks expect to derive from regular exercise, a new study says.

The protective effect exercise should have on people’s risk of death was cut by half among those living in areas with heavy air pollution, researchers reported recently in the journal BMC Medicine.

“Our study shows that toxic air can to some extent block the benefits of exercise, although not eliminate them,” researcher Andrew Steptoe, a professor of psychology and epidemiology with University College London, said in a news release.

“The findings are further evidence of the damage that fine particle pollution can do to our health,” Steptoe continued. “We believe clean air and physical activity are both important for healthy aging and so we encourage greater efforts to curb health-harming pollution levels.”

For the study, researchers pooled data from seven prior studies involving more than 1.5 million people, of whom 115,000 had died. The people lived in countries like the United States, United Kingdom, Taiwan, China and Denmark.

Results showed that people who got at least two and a half hours of moderate to vigorous exercise each week had a 30% lower risk of death, compared to those who worked out less.

However, this reduction in death risk was cut in half — to between 12% and 15% — if people lived in an area with high levels of particle pollution, researchers found.

And, as researchers looked at a higher tier of particle pollution, the benefits of exercise were weakened even more, results show.

Nearly half the world’s population (46%) live in places exceeding the safe threshold for particle pollution, researchers noted.

Particle pollution involves airborne particles 2.5 micrometers in diameter, according to the U.S. Environmental Protection Agency. By comparison, a human hair is 50 to 70 micrometers wide.

“Our findings emphasize that exercise remains beneficial even in polluted environments. However, improving air quality can greatly enhance these health gains,” lead researcher Po-Wen Ku, a professor with National Chung Hsing University in Taiwan, said in a news release.

Researchers emphasized that active folks shouldn’t let this news deter their efforts.

“We don’t want to discourage people from exercising outdoors,” researcher Paola Zaninotto, a professor of medical and social statistics with University College London, said in a news release. “Checking air quality, choosing cleaner routes, or easing off intensity on polluted days can help you get the most health benefits from your exercise.”

SOURCES: University College London, news release, Nov. 27, 2025; BMC Medicine, Nov. 28, 2025

Active people should avoid exercising outdoors on days with poor air quality.