Ambient air pollution and human performance: Contemporaneous and acclimatization effects of ozone exposure on athletic performance.

This paper utilizes a unique dataset of competitive outcomes from intercollegiate track and field competition to identify the relationship between recent ambient pollution exposure histories and human performance among a young and fit population in a diverse range of physically demanding "tasks". I find that higher contemporaneous ozone levels are associated with poorer performances in events that heavily tax the respiratory system. This is the case despite the low exposure levels observed in the studied sample, which are similar to those regularly experienced across the developed world. Such negative performance effects imply that observed ozone exposures are leading to physiological harm, which can be expected to negatively impact economic outcomes through both health and productivity channels. Leveraging the unique structure of the data- which includes location information for competitions and home institutions- I also identify an acclimatization effect whereby recent exposure to higher ozone levels serves to reduce the negative effects of contemporaneous exposure. This finding underscores the importance of regulating peak ozone levels rather than only mean concentrations, as spikes in ambient ozone levels can be particularly damaging to exposed populations.