Air pollution negatively affects marathon performance

When marathon runners train, their minds typically focus on mileage, nutrition, and gear. Yet recent research from the Brown University School of Public Health suggests that runners may also need to think about the air they breathe on race day. 

According to a new study published in Sports Medicine, higher levels of fine particulate matter in the air are linked to slower average marathon finish times.

“Runners at that level are thinking about their gear, their nutrition, their training, the course, even the weather,” said study author Elvira Fleury, who conducted the research while enrolled as a graduate student at Brown University and is now a doctoral student at Harvard University.

“Our results show that those interested in optimizing athletic performance should consider the effect of air pollution, as well.”

Large-scale analysis across major marathons

The study drew on finish times from 1,506,137 male and 1,058,674 female participants who ran in nine major marathons throughout the United States – including Boston, Houston, and Los Angeles – between 2003 and 2019. 

By combining publicly available race data with a sophisticated statistical model developed by Allan Just, an associate professor of epidemiology and environment and society at Brown, the researchers could determine the amount of fine particulate matter at various points along each course.

“This really sophisticated spatial-temporal model of particulate matter allowed us to plot pollution at every mile of every course,” Fleury said. “Without a model like this, it wouldn’t have been possible to look at so many different marathons in different states across different years.”

Air pollution and marathon performance

Fine particulate matter, known as PM2.5, consists of airborne particles smaller than 2.5 microns in diameter and originates from sources like forest fires, vehicle emissions, and industrial activities. 

Analyzing the data, the researchers found that every 1 µg/m³ increase in PM2.5 was associated with slower finish times: on average, 32 seconds slower among men and 25 seconds slower among women. The effect was particularly evident among faster-than-median runners, suggesting that even elite athletes might be affected.

Although these time differences may seem small, Fleury pointed out that they matter greatly in elite competitions, where the margin between victory and defeat or achieving a personal record can be just a few seconds.

“Think of all the effort, time and money that a professional runner like Eliud Kipchoge put into trying to break the world record and run a marathon in less than two hours,” Fleury said. “Every second matters.”

Marathon runners exposed to air pollution

While previous research has linked air pollution to health issues like heart disease, lung disease, and even mortality, this study examined its impact on the athletic performances of fit, well-trained individuals. 

The researchers suggested that exposure to air pollution could lead to increased blood pressure, constricted blood vessels, reduced lung function, respiratory discomfort, or short-term cognitive difficulties – factors that together might slow a runner’s pace.

“People who can complete a marathon are generally quite healthy, and we can assume they have honed their cardiorespiratory fitness,” said study author Joseph Braun, a professor of epidemiology at Brown’s School of Public Health. 

“This study revealed a negative impact from air pollution, even at levels below current health-based standards, on these very healthy people. This means that air pollution can be a health risk not just for those who are elderly or susceptible – it can negatively affect even the most healthy and well-trained among us.”

Broader implications of the research

The results serve as a reminder that if air pollution can hamper marathon runners – often among the healthiest individuals – then the general population may also face health risks from polluted air. 

The researchers concluded that efforts to lower pollution through regulation of power generation, industry, and transportation not only protect public health but may also help athletes perform at their peak.

For runners striving to set new personal records, paying attention to air quality forecasts could be one more step toward success. 

For policymakers and environmental advocates, these findings underscore the importance of continuing efforts to reduce air pollution, ensuring a healthier environment for everyone – from elite athletes to casual joggers and beyond.

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