Air Pollution Slows Marathon Runners, Study of 2.7 Million Finishers Shows

A new study links race-day air pollution to slower marathon times, with amateur runners losing minutes that add up at the finish. Researchers at the University of Leicester analyzed 2,756,553 results from the six World Marathon Majors—Berlin, Boston, Chicago, London, New York City and Tokyo—across 75 races from 2010 to 2024, published in Sports Medicine - Open. After accounting for heat, humidity and wind, each additional microgram of nitrogen dioxide per cubic metre was associated with finishing times about 1.4 to 1.6 minutes slower. Moving from cleaner to more polluted conditions reduced performance by about 7.3 minutes for men and 7.9 for women on average, using Copernicus Atmosphere monitoring data.