Pollution characteristic and health risk of PAHs in ambient PM_2.5 in Zhenjiang, China

Objective To investigate the pollution levels of polycyclic aromatic hydrocarbons (PAHs) in ambient fine particulate matter in Zhenjiang, Jiangsu province, China, and to evaluate the health risk of respiratory exposure to PAHs.

Methods Ambient fine particulate matter samples were collected at the monitoring point of Dantu district in Zhenjiang during 10th to 16th of every month from 2017 to 2021 to analyze the contents of 16 types of PAHs, followed by health risk evaluation according to the Technical Guide for Environmental Health Risk Assessment of Chemical Exposure (WS/T 777-2021).

Results The average annual concentration of the 16 types of PAHs was 5.52 ng/m³, ranging from 4.61 to 8.11 ng/m³. The concentrations of PAHs were generally highest in winter, followed by spring, autumn, and summer. PAHs were mainly composed of 5-6 rings, mainly from vehicle exhaust emissions and coal combustion. Based on the median toxic equivalent concentration, the hazard quotient (HQ) values of PAHs in ambient fine particulate matter from 2017 to 2021 were all less than 1, and the carcinogenic risk (CR) estimates were all less than 1×10^-6. Based on the 95th percentile of toxic equivalent concentration, the HQ values of PAHs in ambient fine particulate matter ranged from 1.22 and 3.27 in Zhenjiang from 2017 to 2021. The HQ values were between 1.21 and 2.91 in spring, autumn, and winter, and 0.46 in summer. The CR estimate was 1.68×10^-6 in 2017 and 6.27×10^-7 to 9.64×10^-7 from 2018 to 2021. The CR estimates were between 2.34×10^-7 and 6.68×10^-7 in spring, summer, and autumn, and 1.49×10^-6 in winter.

Conclusion PAHs in ambient fine particulate matter in Zhenjiang have potential carcinogenic and higher non-carcinogenic risks at high concentrations.