Seasonal variation and health risk assessment of atmospheric PM2.5-bound polycyclic aromatic hydrocarbons in a classic agglomeration industrial city,central China

Sixty atmospheric sample concentrations of PM_2.5 and polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were analyzed in distinct seasonal variations from a classic agglomeration industrial city. The concentrations of PM_2.5 ranged from 6.96 to 260.06 μg/m³ with an average of 177.05 μg/m³. Only 38% of the sampling days were superior to the 24-h limit value (75 μg/m³) of ambient air quality standards (AAQs), and the samples from autumn and winter exceeded the limit value. The total PAHs ranged from 1.51 to 44.51 ng/m³ with an average of 10.65 ng/m³. The highest and lowest concentrations of total PAHs appeared in winter and summer with averages of 22.56 and 4.03 ng/m³, respectively. Correlation analysis revealed that high-molecular-weight PAHs (HMW-PAHs) (4-, 5-, 6-ring PAHs) were significantly and negatively correlated with temperature and water-soluble total organic carbon (WTOC), and significantly correlated with water-soluble total nitrogen (WTN). The 4-, 5- and 6-ring PAHs were dominant, especially those of 4-ring PAHs, which were above 30% of the total PAHs in each season. Source apportionment indicated that PM_2.5-bound PAHs in Huangshi were mainly derived from pyrogenic source, vehicle exhaust, coal combustion, and biomass burning. Incremental lifetime cancer risks (ILCRs) showed no potential carcinogenic risk from the PM_2.5-bound BaP-eq. ILCRs in winter were the highest, and the risks for adults were approximately an order of magnitude higher than those for children.