Scientific American, 28 February 2025

How Bad Air Quality Slows Down Marathon Runners

Even modest amounts of air pollution may affect athletic performance, a new study finds.

Ask any marathon runner a week before their big race what they are doing, and they’ll almost certainly be refreshing the weather app on their phone. That’s because humid conditions, freezing rain or even a day that is too sunny and hot can cause them to be slower during a race than they were in training. Runners spend months training for marathons, and it can be crushing if their hard-earned performance is affected by something that is completely out of their control, such as the weather. Now these athletes might have another factor to obsess over in the days leading up to their race: air quality.