Concentrations, properties, and health risk of PM2.5 in the Tianjin City subway system

Wang, Bao-Qing; Liu, Jian-Feng; Ren, Zi-Hui; Chen, Rong-Hui

Concentrations, properties, and health risk of PM2.5 in the Tianjin City subway system

2016

Wang, Bao-Qing | Liu, Jian-Feng | Ren, Zi-Hui | Chen, Rong-Hui

A campaign was conducted to assess and compare the personal exposure in L3 of Tianjin subway, focusing on PM₂.₅ levels, chemical compositions, morphology analysis, as well as the health risk of heavy metal in PM₂.₅. The results indicated that the average concentration of the PM₂.₅ was 151.43 μg/m³ inside the train of the subway during rush hours. PM₂.₅ concentrations inside car under the ground are higher than those on the ground, and PM₂.₅ concentrations on the platform are higher than those inside car. Regarding metal concentrations, the highest element in PM₂.₅ samples was Fe; the level of which is 17.55 μg/m³. OC is a major component of PM₂.₅ in Tianjin subway. Secondary organic carbon is the formation of gaseous organic pollutants in subway. SEM–EDX and TEM–EDX exhibit the presence of individual particle with a large metal content in the subway samples. For small Fe metal particles, iron oxide can be formed easily. With regard to their sources, Fe-containing particles are generated mainly from mechanical wear and friction processes at the rail–wheel–brake interfaces. The non-carcinogenic risk to metals Cr, Ni, Cu, Zn and Pb, and carcinogenic hazard of Cr and Ni were all below the acceptable level in L3 of Tianjin subway.

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