Chasing Clean Air: Pollution-Induced Travels in China

This study uses "big" data to empirically investigate a highly effective, but underexamined way of reducing one's exposure toward air pollution-short-term travel. We determine subscribers' locations using mobile phones' signals and thereby establish linkages between air pollution and short-term population movements between cities in China. Using an instrumental variable based on daily variation in wind directions and pollution levels from distant upwind locations, we find that a one-unit increase in the origin city's air quality index (AQI) over the destination city's AQI increases short-term population flow from origin to destination by 0.15%. Further analyses provide richer characterizations of the decision-making process behind travel movements. Our findings add to the evidence base by examining in detail an understudied behavioral response toward air pollution.