[Size Distribution Characteristics and Inhalation Exposure of Particle-Bound PAHs in an Industrial City]

Atmospheric particulate matter was collected during the heating period and the non-heating period of a typical steel industrial process in Northeast China to study the following:① the size-depended distribution and enrichment characteristics of polycyclic aromatic hydrocarbons (PAHs); ② the deposition concentrations of PAHs of different particle sizes in various organs of the human respiratory system; and 3 the risk from human respiratory exposure. The 14 priority PAHs in the samples were determined by high-performance liquid chromatography (HPLC), and respiratory exposure assessment was conducted by combining the atmospheric particle size fractionation sampling technique with an internal deposition model. The results showed that the PAH concentrations during the heating periods (743.9 ng·m^-3) were higher than those during the non-heating periods (169.0 ng·m^-3). Most PAH contributions (86.3%-89.9%) were related to fine particles with a diameter ≤ 2.06 μm; medium and low molecular weight PAHs showed two concentration peaks in 1.07-2.06 μm and 7.04-9.99 μm range, respectively. In contrast, high molecular weight PAHs showed a unimodal peak in 1.07-2.06 μm range. Four-ring PAHs accounted for 40% of the total PAHs concentrations. With respect to human exposure, 53.3% and 55.3% of the granular PAHs were deposited in the lungs during the heating and non-heating periods, respectively. The incremental lifetime cancer risk (R) of particulate PAHs in the population was calculated using the concentration in the human respiratory system and the total concentration associated with the particulate matter. The R values for adults ranged between 1.3×10^-5 and 2.9×10^-5 during the heating period, and between 3.1×10^-6 and 6.0×10^-6 during the non-heating period. The R values for children during the heating period ranged between 1.0×10^-5 and 2.3×10^-5, and between 2.4×10^-6 and 4.8×10^-6 during the non-heating period. The results indicated that particle size greatly affected the concentrations of particles deposited in the respiratory system and the level of carcinogenic risk. The combination of the grading sampling technique and the respiratory system settlement model can effectively avoid the over-evaluation of human respiratory exposure.