Where do people spend their leisure time on dusty days? Application of spatiotemporal behavioral responses to particulate matter pollution

In recent years, the deterioration of air quality due to high levels of particulate matter (PM: especially PM 10 and PM 2.5) has become a transboundary environmental problem in countries of the East Asia Pacific region. People tend to change their behavior in response to bad air quality, and those changes generate a wide range of socioeconomic implications. Despite their significance, however, the effects of PM on human behavior, especially behaviors involving outdoor activities, have not been sufficiently examined. This study employed panel analyses to empirically investigate differences in the preferences for recreational spaces with changes in the PM 2.5 level in Seoul, South Korea, from March 1 to June 30, 2017. We found a statistically significant relationship between the PM 2.5 level and the number of visitors to particular types of study sites in the daytime on weekdays and all days of the weekends. In both time groups, the number of visitors in open spaces decreased, while those in commercial spaces increased with heightened PM 2.5 level. But the numbers of visitors to indoor sports facilities showed no significant changes with the level of PM 2.5. We also found differing levels of pedestrian volume change according to sub-categories of open and commercial spaces. As an early empirical study of the impact of PM on human behavior, this work will help evaluate environmental policies and make possible safer community development planning.