Nitrogen dioxide levels impact marathon runner performance

A study published in the journal ‘Sports Medicine’ has found that nitrogen dioxide (NO2) levels significantly impact marathon performance. Researchers from the University of Leicester analyzed data from over 2.7 million finishers across six major international marathons—Berlin, Boston, Chicago, London, New York, and Tokyo—between 2010 and 2024.

The research indicates that for every additional microgram of NO2 per cubic meter of air, men’s finish times increased by an average of 1.43 minutes, while women’s times increased by 1.56 minutes. In contrast, particulate matter (PM 2.5) did not show a statistically significant influence on running times.

The impact was notably higher among recreational runners, who were affected approximately six times more severely than elite athletes. Specifically, recreational runners saw an average delay of 2.12 minutes per microgram of NO2, compared to just 0.34 minutes for elite performers. Age also played a role, with runners aged 18 to 29 experiencing stronger effects than those over 60.