LAUSR

Because of their unintentional formation and low vapor pressure, polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (XPAHs) in the atmosphere are distributed primarily to aerosolized particles with an aerodynamic diameter less than 2.5 μm (PM2.5). However, no information is available regarding the occurrence of PM2.5-bound PAHs and XPAHs in Bangladesh, one of the most highly PM2.5-polluted regions worldwide. In this study, we investigated the occurrence of PM2.5-bound PAHs and XPAHs in the atmospheres of Dhaka in Bangladesh and Shizuoka in Japan (as a reference) and estimated their incremental lifetime cancer risks (ILCRs). In addition, we statistically estimated the potential sources of PM2.5-bound PAHs and XPAHs by using principal component analysis and positive matrix factorization. The median concentration of total PM2.5-bound PAHs and XPAHs in Bangladesh was 24.2 times that in Japan. The estimated potential sources of PAHs clearly differed between Japan and Bangladesh, whereas those of XPAHs were largely (>80%) unknown in both countries. The median ILCR in Bangladesh was 2.81 × 10-3, which greatly exceeded the upper limit of acceptable risk (10-4). These results indicate that comprehensive monitoring and control of atmospheric PM2.5-bound PAHs and XPAHs are needed urgently, especially in highly polluted countries.