Investigation into atmospheric PM_2.5-borne PAHs in Eastern cities of China: Concentration, source diagnosis and health risk assessment

This study investigated PM_2.5-PAHs associations collected in Beijing, Jinan, and Shanghai in Eastern China. The results indicated that PM_2.5 concentrations in Beijing, Jinan, and Shanghai were 125.7 μg m^-3 (18.6-355.5 μg m^-3), 115.9 μg m^-3 (44.2-345.4 μg m^-3), and 85.1 μg m^-3 (24.3-232.8 μg m^-3), respectively. The PAH concentrations in terms of PM_2.5 in Beijing, Jinan, and Shanghai ranged from 23.2 to 819.8 ng m^-3, 25.7 to 727.1 ng m^-3, and 8.5 to 133.9 ng m^-3, respectively. PAH concentrations were found to be positively correlated with PM_2.5 concentration in Beijing and Shanghai. The compositions of PAHs in PM_2.5 in Beijing and Jinan were almost the same: 11% low ring, 80-82% middle ring, and 7-9% high ring. However, Shanghai had a different composition. Source apportionment indicated that the incomplete combustion of coal and diesel and gasoline emissions were the main sources of PAHs in PM_2.5 in all three cities, whereas Shanghai had a greater contribution from liquid fossil fuels. The values for the health risk assessment estimated by the benzo[a]pyrene equivalent concentration in Beijing and Jinan were 2.39 × 10^-6 and 2.57 × 10^-6, respectively, thus both exceeding the 1 × 10^-6 limit (USEPA) considered likely to pose an inhalation cancer risk to people. Shanghai, however, had a risk estimate of 5.05 × 10^-7, which is still in a safe range. This study is the first to simultaneously monitor the PAHs in PM_2.5 in three cities in Eastern China and may point to a long-range transportation of PM_2.5-PAHs from Beijing to Jinan and partially to Shanghai.