Running with a Mask? The Effect of Air Pollution on Marathon Runners’ Performance

Using a sample of over 0.3 million marathon runners in 37 cities and 55 races in China in 2014 and 2015, we estimate the air pollution elasticity of finish time to be 0.041. Our causal identification comes from the exogeneity of air pollution on the race day because runners are required to register a race a few months in advance and we control for city fixed effects, seasonal effects, and weather condition on the race day. Including individual fixed effects also provides consistent evidence. Our study contributes to the emerging literature on the effect of air pollution on short-run productivity, particularly on the performance of athletes engaging outdoor sports and other workers whose jobs require intensive physical activities.