Effect of platform screen doors on the indoor air environment of an underground subway station

Contaminant concentrations in a subway station in Seoul, Korea before (March 2008) and after (March 2009) the installation of platform screen doors (PSDs) were measured to investigate the effect of the PSD system on the subway indoor environment. PM 10 , CO 2 and NO 2 concentrations were measured at the platform, concourse and tunnel areas, using an indoor air quality tele-monitoring system (IAQ-TMS) operated by the Korean Ministry of Environment. Spatial correlations of contaminant concentrations at different locations were analysed, to investigate the effect of PSD installation on the movement of contaminants through air passages between zones. The results indicate that PM 10 concentrations at the platform were reduced significantly after PSD installation and were within the guideline limit. The R 2 value for the platform–tunnel correlation was reduced, indicating that in the absence of PSD, a significant amount of particulate matter was introduced to the platform from the tunnel. Conversely, the CO 2 level in the platform was increased slightly after PSD installation, exhibiting a strong correlation with the number of passengers in the station. NO 2 was predominantly introduced to the platform from the outdoor environment, on the basis of the source characteristics and their movement through air passages. This paper provides the data to develop a pollution management guide to control air quality contaminants in subway stations.