National Chung Hsing University Graduate Institute of Sports and Health Management distinguished professor Ku Po-wen speaks at a news conference in Taipei yesterday. Photo: CNA

By Lee I-chia / Staff reporter

A new cross-national study led by researchers from National Chung Hsing University （NCHU） found that regular physical activity benefits can be reduced when people exercise while exposed to highly polluted air, the university said yesterday.

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The international research, led by Ku Po-wen （古博文）, a professor in NCHU’s Graduate Institute of Sports and Health Management, assessed whether air pollution could have an impact on the health benefits of regular exercise.

Researchers conducted a meta-analysis on seven cohort studies, involving more than 1.52 million adults in places including Taiwan, the UK, the US, Denmark and China, with all of the subjects tracked for more than a decade.

For assessing the levels of air pollution, the researchers focused on PM2.5 — tiny particles measuring 2.5 micrometers or less that are small enough to penetrate deep in people’s lungs and enter the bloodstream.

The research found that the benefits of regular exercise on people’s health — such as reducing risk of death from illnesses such as cancer and heart disease — are reduced for those living in high pollution areas.

Researchers found that people who did at least 2.5 hours of moderate or vigorous exercise a week had a 30 percent lower risk of dying during the study period than those who did not, Ku said.

However, if people in the physically active group lived in an area with high fine particle pollution — a yearly average PM2.5 concentration level of 25 micrograms per cubic meter （mg/m3） or higher — then this reduction in mortality risk halved to about 12 to 15 percent, he said.

Moreover, at higher levels of fine particle pollution — a yearly average PM2.5 concentration level of 35mg/m3 or higher — the benefits of regular exercise weakened further, particularly for risk of death from cancer, to a point where the benefits were no longer robust, he said.

Approximately 46 percent of the global population live in areas exceeding the 25mg/m3 or higher threshold, and about 36 percent live in areas exceeding the 35mg/m3 or higher threshold, he said.

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

In Taiwan, the overall air quality has improved in the past few years, and the nationwide yearly average PM2.5 level is below 25mg/m3 but air quality differs across the country, Ku said.

Air pollution levels can increase due to changes in weather, traffic flow, topography and other factors, he said.

In addition, many people in Taiwan like to participate in outdoor physical activities, such as marathons or other road running events, he said, suggesting people to develop a habit of checking the real-time air quality before exercising outdoors.

The study was published in the journal BMC Medicine last month.

新聞來源：TAIPEI TIMES

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