Study finds pollution reduces some protective benefits of exercise
The study does not argue that outdoor exercise should be avoided. Even when air quality is less-than-ideal, exercise continues to provide protective benefits.
A new large-scale study using the data of over a million adults from across the globe finds that prolonged exposure to polluted air diminishes the protective power of exercise.
“While exercise still helps people live longer, its benefits shrink dramatically in regions with heavy fine particle pollution—especially above key PM2.5 thresholds common in many parts of the world,” reads an excerpt of a statement from the research team at University College London (UCL).
The paper does not argue that exercise should stop. Instead, it pushes for better air quality, which compounds the positive effects of exercise.
For their paper, researchers looked at data from more than 1.5 million adults from high-income countries who were monitored for a decade across several countries, including parts of Europe, Asia, and North America.
They focused on the impact of fine particulate matter, or PM2.5, which is small enough to travel into the lungs and enter the bloodstream.
“Exercise benefits declined sharply when yearly average PM2.5 levels reached 25 micrograms per cubic meter (μg/m3) or higher. Nearly half (46 per cent) of the global population lives in regions where pollution is at or above this level,” reads the UCL statement.
But the authors are quick to point out that while pollution reduces the benefits of exercise, it does not completely erase them.
Even when the negative effects of pollution exposure are accounted for, participants who completed at least 2.5 hours of moderate to vigorous activity weekly had a 30 per cent lower risk of death compared to people who did not.
But the protective effect dropped to 12-15 per cent for active individuals living in areas where PM2.5 pollution exceeded 25 μg/m3 or, in other words, areas with consistently high pollution levels. Individuals in areas with PM2.5 exceeding 35 μg/m3, which represents about 36 per cent of the global population, saw their benefits even further reduced.
It’s not clear how people in lower-income regions fare as they were underrepresented in the study, although air quality in these regions can sometimes surpass 50 μg/m3, UCL says.
The authors also did not account for indoor air quality or details about the participants’ diets.
Once again, the paper does not state that outdoor exercise should be avoided. Even when air quality is less-than-ideal, exercise continues to provide protective benefits.
A separate and unrelated study found there are numerous benefits to spending time outdoors in nature, including better health outcomes and higher concentration levels.