A campaign was conducted to assess and compare the personal exposure in L3 of Tianjin subway, focusing on PM levels, chemical compositions, morphology analysis, as well as the health risk of heavy metal in PM. The results indicated that the average concentration of the PM was 151.43 μg/m inside the train of the subway during rush hours. PM concentrations inside car under the ground are higher than those on the ground, and PM concentrations on the platform are higher than those inside car. Regarding metal concentrations, the highest element in PM samples was Fe; the level of which is 17.55 μg/m. OC is a major component of PM 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.
The indoor and outdoor PM mass concentration, water-soluble ion by filter sampler was analyzed on December 3-21, 2015 during wintertime in Tianjin, China. The results indicate that high humidity conditions result in the accumulation of atmospheric pollutants and reduce atmosphere visibility. The I/O ratio for PM concentration in dormitory and lab are less than 1 in haze days. Indoor PM concentration increases rapidly with outdoor PM concentration increasing in haze days. The filtration factors of the dormitory and lab indicate nearly half of the outdoor PM enters indoor environment. The human activities in dormitory could cause more the formation of PM than those in lab. The concentration of SO is the highest ion in water-soluble ion for outdoor PM. The SO, NO, NH, and Cl are generated mainly by outdoor sources; however, the Na, Ca, and Mg are generated mainly by indoor sources. The NHNO, (NH)SO, and NHCl accounts for 20.2~41.8%, 32.0~51.4%, and 6.4~10.6% of the total water-soluble ion in different indoor-outdoor environment. The total secondary aerosols including NHNO, (NH)SO, and NHCl in PM are 28.3, 42.1, 28.2, 31.0, and 33.9% in outdoor environment for haze days, outdoor environment for non-haze days, dormitory for haze days, dormitory for non-haze days, and lab for haze days, respectively.
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