Characteristics, Sources and Improvement Measures Regarding Fine Particulate Matter in Subway Station Work Areas

Abstract

Metro staff usually stay in the work area of subway stations for more than eight hours. Therefore, fine particulate matter (PM2.5) can have a great impact on the health of staff. In order to study the characteristics and sources of PM2.5 in the subway station work area, three different types of typical subway station were selected for sampling and analysis. The results show that the concentration of PM2.5 in the work area is generally higher than outdoors and exceeds the guidance value given by the World Health Organization. Twenty-two elements in the PM2.5 samples collected were analyzed, among which Fe is the element with the highest concentration, which is three to 12 times that of outdoors, and PM2.5 in the work area is highly enriched with metal elements. The mass balance equation with elemental Fe as the tracer element is established, and the transport path of PM2.5 in the work area is revealed: if the work area is obviously under positive pressure compared to the station hall, the elemental Fe comes from the air supply of the ventilation and air conditioning (VAC) system, as does the metal-enriched PM2.5; if the work area is under negative pressure, the elemental Fe comes from the air supply of the VAC system and air infiltration from the station hall, and the contribution of air infiltration to Fe mass can reach 50%. Finally, following an investigation into the source of fine particles in the work area, measures to improve air quality are proposed.

Keywords: Fine particulate matter, Subway station work area, Composition, Tracer element, Transport path, Improvement measures