Climate change is making air quality worse in many parts of the world. Rising temperatures increase ground-level ozone and more frequent wildfires release harmful smoke and particulates into the air. These shifts, together with ongoing pollution from vehicle exhaust and industrial emissions, are leading to longer and more intense episodes of unhealthy air.
According to a new study led by researchers from University College London, long-term exposure to this polluted air may significantly reduce the positive health benefits typically gained from regular exercise.
The researchers examined data from more than 1.5 million adults who were monitored for more than ten years across several countries, including the UK, China, and the United States. They focused on levels of fine particulate matter, known as PM2.5, which are extremely small particles that can lodge deep in the lungs and even slip into the bloodstream.
The study, which was recently published in the journal BMC Medicine, found that adults who exercised at least two and a half hours per week had a 30% lower risk of death. But this dropped to 12–15% for highly active people in areas where yearly average PM2.5 levels reached 25 micrograms per cubic meter or higher.
Alarmingly, nearly half of the global population lives in regions where pollution is at or above this level.
The researchers stress that exercise still helps - just not as much when the air is dirty. They recommend checking local air-quality reports, choosing cleaner routes, or reducing intensity on high-pollution days.
Improving air quality could dramatically enhance the health benefits of exercise.
