Measurement of size-segregated airborne particulate bound polycyclic aromatic compounds and assessment of their human health impacts - A case study in a megacity of southwest China.

Particle size distribution of particulate polycyclic aromatic compounds (PACs) is one of the important factors controlling human exposure to PACs in air. In this study, size-segregated airborne particle samples were collected in a megacity in southwest China to analyze PACs concentrations and evaluate related health risks. Annual average concentrations of ΣPAHs (polycyclic aromatic hydrocarbons, 17.4 ng/m) and ΣOPAHs (oxygenated PAHs, 15.3 ng/m) were one order of magnitude higher than those of ΣMPAHs (methyl PAHs, 0.97 ng/m) and ΣNPAHs (nitrated PAHs, 1.54 ng/m). More than 55% of PACs masses were associated with fine particles (aerodynamic diameter D < 2.1 μm). Inhalation exposure assessment showed that less than 60% of particulate bound PACs could deposit in the respiratory tract, which implies that the traditional model using ambient concentration of PACs would overestimate the inhalation risk. On the other hand, incremental lifetime cancer risks from dermal absorption (ILCR) were comparable to those from inhalation (ILCR) exposure despite the much lower daily dermal absorption dose than the daily inhalation dose, which implies that the health impact might be underestimated if only considering inhalation exposure. Cancer risks from inhalation exposure were mainly attributed to fine particles while those from dermal exposure were mostly associated with coarse particles. Although neither ILCR nor ILCR exceeded the threshold value of 10 set by USEPA, the total ILCR exceeded this criterion, manifesting potential health risks from exposure to airborne particulate PACs in this region.