How does air pollution affect travel behavior? A big data field study

Exposure to ambient air pollution causes 4.2 million deaths worldwide every year; thus, people may avoid traveling on polluted days. However, the extant studies have mixed findings of the travel behavior on polluted days, caused by the shortcomings of survey data and specific activity data. In order to fulfill this research gap, this study evaluates the relationship between air pollution and travel behavior based on approximately 4.6 billion mobile positioning records in Xi'an, China. Moreover, this study also investigates how different demographic groups travel differently on polluted days. The results indicate that air pollution has a significantly negative correlation with travel behavior. Specifically, (1) people reduce travel distance slightly but reduce travel area greatly; and (2) younger people (50 and under) reduce more travel area while older people (over 50) reduce more travel distance on polluted days.