TAIPEI (Taiwan News) — A Taiwan researcher said Wednesday that long-term exposure to high concentrations of PM2.5 can reduce the health benefits of regular exercise by up to half, based on a review of 10 years of data from more than 1.5 million adults in five countries, per CNA.

Ku Po-wen (古博文), a professor at National Chung Hsing University’s Institute of Sports and Health Management, spent three years studying the effects of long-term exposure to environments with PM2.5 levels exceeding 25 micrograms per cubic meter. His team conducted what he said was the first systematic review, combining data from seven large-scale, long-term multinational studies.

Ku found that adults who perform the recommended 150 minutes of moderate-intensity exercise per week can reduce all-cause mortality by about 30% when annual average PM2.5 concentrations are below 25 μg/m³. However, when annual average concentrations exceed 25 μg/m³, the same level of exercise reduces mortality risk by only 12% to 15%, cutting the benefit roughly in half.

He noted that Taiwan’s overall air quality has improved significantly in recent years, with annual average PM2.5 concentrations now below 25 μg/m³ in all counties and cities. Still, he cautioned that annual averages may not reflect real conditions, as PM2.5 levels can spike due to seasonal changes, weather patterns, topography, traffic, or localized pollution.

Ku advised the public to check the real-time air quality index and choose exercise times or locations with cleaner air. His research was published in the medical journal BMC Medicine.