Composition, Source Apportionment, and Health Risk of PM 2.5 -Bound Metals during Winter Haze in Yuci College Town, Shanxi, China.

The composition, source, and health risks of PM 2.5 -bound metals were investigated during winter haze in Yuci College Town, Shanxi, China. The 24-h PM 2.5 levels of 34 samples ranged from 17 to 174 μg·m -3 , with a mean of 81 ± 35 μg·m -3 . PM 2.5 -bound metals ranked in the following order: Zn > Cu > Pb > As > Ni > Cr (VI) > Cd > Co. The concentrations of 18% As and 100% Cr (VI) exceeded the corresponding standards of the Ambient Air Quality Standards set by China and the WHO. Subsequently, positive matrix factorization analyses revealed that the three major sources of metals were combustion (37.91%), traffic emissions (32.19%), and industry sources (29.9%). Finally, the non-carcinogenic risks for eight metals indicated that only 2.9% of the samples exceeded a threshold value of one, and As accounted for 45.31%. The total carcinogenic risk values for six metals (As, Cd, Co, Cr (VI), Ni, and Pb) were in the range from 10 -6 to 10 -4 , with Cr (VI) and As accounting for 80.92% and 15.52%, respectively. In conclusion, winter haze in Yuci College Town was characterized by higher metal levels and health risks; among the metals, As and Cr (VI) were probably the main contributors.