Temporal and spatial characteristics of particulate matters in metro stations of Shanghai, China

Abstract

The aim hereof is designed to understand the temporal and spatial characteristics and influencing factors of particulate matter (PM) in Shanghai Metro stations. A field measurement campaign was performed in two Shanghai Metro stations for 26 days of one year to detect the concentrations of PM10 and PM2.5 (particles with an aerodynamic diameter of 10 or 2.5 μm or less) at different sites. Significant seasonal variations in PM were observed and higher PM concentrations were obtained during the autumn and winter. The spatial distribution of PM was characterized by a tendency to increase with distance from the ground, and the highest PM levels were observed in tunnel. The PM levels were also higher in rush hours than in off-rush hours. The contribution of PM2.5 to PM10 was higher in autumn and winter than that in spring and summer. Fifteen elements in PM2.5 were measured by inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of all elements in tunnel were higher than the atmospheric environment except for As and Se. The relatively high concentrations of metal elements in metro particles were Fe, Al, Ba and Mn. The enrichment factors (EF) showed that Cd, Cu, Zn, Se, Fe, Pb, Ba, Cr, Mn, Co originated from anthropogenic sources. This study showed that PM pollution existed in Shanghai metro stations and the PM levels were affected by outdoor air and train operation. Further monitoring and intervention action is needed to improve metro microenvironment.