Meteorological dependence, source identification, and carcinogenic risk assessment of PM 2.5 -bound Polycyclic Aromatic Hydrocarbons (PAHs) in high-traffic roadside, urban background, and remote suburban area

The Polycyclic Aromatic Hydrocarbons (PAHs) bound to ambient fine Particular Matter (PM 2.5 ) are currently drawing a lot of attention due to their adverse health effects increasing lung cancer risk in humans. In this study, The PM 2.5 samples were collected by high volume air samplers simultaneously from three different sites (high-traffic roadside, urban background, and remote suburban) in Tehran, Iran during warm and cold seasons (from July 2018 to March 2019), and 16 PAHs were analyzed using Gas Chromatography-Mass Spectrometry (GC–MS). Unlike previous studies, a remote suburban area was chosen so as to observe the spatial differentiation in PM 2.5 -bound PAH characteristics. In high-traffic roadside site, the average concentration of total PM 2.5 -bound PAHs (ƩPAHs) was 3.7 times the concentration value in remote suburban area. Average (ƩPAHs) ranged from 5.54 ng/m 3 for remote suburban area to 20.67 ng/m 3 for high-traffic roadside site. In all sites, seasonal trends of PAH concentrations elucidated high concentrations in the cold season and low concentrations in the warm season. Correlation analysis between ƩPAHs and atmospheric factors (meteorology parameters and criteria air pollutants) indicated the heterogeneous processes play an important role in the level of PAHs. The results of diagnostic ratio (DR) analysis disclosed that the dominant source of PM 2.5 -bound PAHs was the combustion of liquid fossil fuels. Despite the fact that incremental lifetime cancer risk (ILCR) via inhaling PM 2.5 -bound PAHs varied significantly in high-traffic roadside site and remote suburban site, its value was beyond the acceptable risk level in both sites. Our results suggested that effective regulations are needed to monitor PAHs concentrations and reduce PAHs emissions from liquid fossil fuel combustion so as to mitigate the potential carcinogenic risk of PAHs in ambient air.