Spatio-Temporal Distribution of Particulate Matter (PM10 and PM2.5) Concentrations in Urban Subway Station - A Case of Nanning in China

Particulate matter is one of the primary air pollutants in urban subway stations. Characteristics of particulate matter concentration is specific due to the heterogeneity of subway system in each city. The spatio-temporal distribution of particulate matter (PM10 and PM2.5) concentrations in a typical urban subway station of Nanning city was analyzed. PM10 and PM2.5 concentrations of winter were both significantly higher than those of spring, summer and autumn (P<0.001). PM10 and PM2.5 concentrations of station were significantly higher than those of the ground control (P<0.001). PM10 and PM2.5 concentrations of ticket office were significantly higher than those of platform, security checkpoint and passageway (P<0.001). PM10 and PM2.5 levels of station during the rush hour were significantly higher than those during the non-rush hour (P<0.001). There is a positive correlation between PM (PM10 and PM2.5) levels and passenger flow of station. The results indicated that the spatio-temporal distribution of PM (PM10 and PM2.5) level may be ascribed to seasonal factor, passenger flow, and layout structure of station respectively. The findings of this study therefore make them possible to be the part of preliminary foundation of subway-related standards improvement for airborne particulate matter in the future.