How To Minimise The Amount Of Polluted Air You Inhale While Exercising
It’s well known that air pollution is linked to chronic health conditions including heart disease, respiratory issues, cancer as well as a higher risk of an early death. According to the World Health Organization, 99% of the global population breathes in polluted air, leading to 6.7 million premature deaths per year.
Air pollution affects pretty much all the organs of your body, says Audrey de Nazelle, an associate professor at Imperial College London who researches the effects of pollution on exercise.
“We used to think it was just respiratory disease, but it’s also [linked to] cardiovascular disease, diabetes, cognitive function and reproductive impacts,” she says.
One major concern is PM 2.5, tiny particles which measure just 2.5 micrometres across. These fine specks are around 30 times smaller than the width of a human hair. They are released directly into the air from traffic, and can penetrate deep into our lungs, crossing into our bloodstream and travelling throughout the body.
Over time, this particle accumulation can affect the brain. In a 2025 review looking at 51 studies, a team analysed data from over 29 million people and found a link between three types of air pollution and an increased risk of dementia. One of these were PM 2.5. “When the particles are this small, they can cross the blood brain barrier, cause damage to the vessels and the barrier, but also end up in your brain,” says Haneen Khreis, an epidemiologist at the University of Cambridge and a co-author of the study.
But there are other pollutants, too. While exercising along busy roads or in cities, we will be breathing in nitrogen dioxide, which was also found by the review to increase the risk of dementia. Nitrogen dioxide is also thought to cause lung inflammation. In the longer term, it can impair how our lungs develop and function. Then there’s sulphur dioxide, ammonia, carbon monoxide and even ground-level ozone.
When we run, cycle or exercise vigorously, we breathe faster and more deeply. That means we tend to inhale more polluted air when running compared to walking. When covering the same distance, people exercising at a higher intensity receive a larger dose of toxic particles entering into their lungs.
How to minimise exposure
For those of us who live in a busy city, we can’t simply uproot ourselves to the countryside for a jog. But the next best option is to find the greenest or least congested area around us. For instance, I have the option to cycle along a road with less traffic on my morning commute, but it does take a few minutes longer.
Research shows that moving one or two streets away from heavy traffic slashes your pollution exposure by 20% to 30%, says de Nazelle. And if you can take side streets, even better. One study found that opting for side streets instead of busy routes cut exposure by 50%.
If possible, it’s also a good idea to avoid rush hour. Cars sitting still in traffic create “pollution hotspots” says Khreis. Similarly, watch out for peaks of ozone during hot sunny afternoons, she advises. She explains that this potent chemical tends to form when it’s really hot and there’s abundant sunlight. Combining these factors with the air pollution at rush hour exacerbates the problem.
