Air Pollution Tied to Diminished Benefits of Regular Exercise

THURSDAY, Dec. 11, 2025 (HealthDay News) — Long-term exposure to polluted air can weaken the health benefits of regular exercise, according to a review published online Nov. 28 in BMC Medicine.

Po-Wen Ku, Ph.D., from University College London, and colleagues conducted a systematic literature review to assess whether higher levels of fine particulate matter (PM_2.5) reduce the protective effects of leisure-time physical activity (LTPA) on all-cause, cardiovascular, and cancer mortality. 

Based on seven cohort studies (1.5 million participants; 115,196 deaths), the researchers found that the reduction in all-cause mortality risk diminished with higher PM_2.5 exposure. Meeting the recommended LTPA level (7.5 to 15 MET-hours/week) was associated with a 30 percent reduced all-cause mortality risk at PM_2.5 <25 μg/m³ but only 12 to 15 percent at >25 μg/m³. Pooled data from three cohorts (869,038 individuals; 45,080 deaths) confirmed this pattern. Among individuals meeting the recommended LTPA level, there was a lower risk for all-cause mortality versus those in the highest-risk group (reference, < 1 MET-hour/week; PM_2.5, 35–50 μg/m³). Risk reductions varied by PM_2.5 exposure (hazard ratios, 0.75, 0.67, 0.34, 0.34, and 0.30 for 35 to 50, 25 to 35, 15 to 25, 10 to 15, and <10 μg/m³, respectively). Across most PM_2.5 exposure categories, higher levels of LTPA were generally associated with lower all-cause and cause-specific mortality, but the protective effects were attenuated at PM_2.5 levels >25 μg/m³ for all outcomes and became nonsignificant for cancer mortality at 35 to 50 μg/m³.

“Our findings emphasize that exercise remains beneficial even in polluted environments,” Ku said in a statement. “However, improving air quality can greatly enhance these health gains.”

Abstract/Full Text