The effect of air pollution on body weight and obesity: Evidence from China

We provide the first study estimating the causal effect of air pollution on body weight and obesity. Using the China Health and Nutrition Survey, which contains detailed longitudinal health and socioeconomic information for 13,741 adult individuals over 1989-2015, we find significant positive effects of air pollution, instrumented by thermal inversions, on body weight. Specifically, a 1 mu g/m(3) (1.54%) increase in average PM2.5 concentrations in the past 12 months increases body mass index by 0.27%, and also increases overweight and obesity rates by 0.82 and 0.27 percentage points, respectively. We also find evidence that these impacts can be explained in part by a variety of behavioral channels, including less physical activity, less walking to work or school, less sleep, and more fat intake.