Air pollution and daily public transportation ridership: The case of Seoul city

This study examines the relationship between air pollution and daily mobility, focusing on daily bus and subway usage in Seoul using panel data with the fixed effects model. This study empirically examines the effect of air pollutant exposure on the daily moving population volume, including daily bus and subway usage in Seoul over 1271 days. The results show that people's sensitivity to particulate matter is complex. The most remarkable aspect of the results is that people are not sensitive to continuous pollutant levels, but to the comprehensive air-quality index (CAI). In addition, people's sensitivity is different depending on the moving distance and the means of transportation. Considering that CAI is defined by adopting the first air quality guidelines proposed by the World Health Organization (WHO) in 2005, these results explain how sensitive people are to the human health risks of particulate matter exposure recommended by the WHO. Our findings can be used as evidence to establish the new particulate matter standards and policies that can be strengthened by reflecting the recently updated WHO's air quality guidelines in 2021.