Investigation of air pollution of Shanghai subway stations in ventilation seasons in terms of PM and PM.

In November 2015, the PM and PM particulate matter (PM) levels in platforms, station halls, and rail areas of the Shangcheng and Jiashan Road Station were monitored to investigate air pollution in the Shanghai subway system. The results revealed that in subway stations, PM and PM concentrations were significantly higher than those in outdoor environments. In addition, particle concentrations in the platforms exceeded maximum levels that domestic safety standards allowed. Particularly on clear days, PM and PM concentrations in platforms were significantly higher than maximum standards levels. Owing to the piston effect, consistent time-varying trends were exhibited by PM concentrations in platforms, station halls, and rail areas. Platform particle concentrations were higher than the amount in station halls, and they were higher on clear days than on rainy days. The time-varying trends of PM and PM concentrations in platforms and station halls were similar to each other. Activities within the station led to most of the inhalable particles within the station area. The mass concentration ratios of PM and PM in platforms were within 0.65-0.93, and fine particles were the dominant components.