Characterization and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban atmospheric Particulate of Tehran, Iran

In this study, atmospheric concentrations of particulate-bound polycyclic aromatic hydrocarbons (PAHs) in Tehran megacity were determined to investigate the concentration, distribution, and sources of PAHs in PM₁₀. The health risk from exposure to airborne BaPeq through inhalation pathway was also assessed. Toxic equivalency factors (TEFs) approach was used for quantitative risk estimate, and incremental lifetime cancer risk (ILCR) was calculated. PM₁₀ samples were collected at ten sampling locations during the summer 2013 and winter 2014 by using two independent methods of field sampling. The PM₁₀ concentration in winter (89.55 ± 15.56 μg m⁻³) was 1.19 times higher than that in summer (75.42 ± 14.93 μg m⁻³). Sixteen PAHs were measured with the total average concentrations of PAHs ranged from 56.98 ± 15.91 to 110.35 ± 57.31 ng m⁻³ in summer and from 125.87 ± 79.02 to 171.25 ± 73.94 ng m⁻³ in winter which were much higher than concentrations measured in most similar studies conducted around the world. Molecular diagnostic ratios were used to identify PAH emission sources. The results indicated that gasoline-driven vehicles are the major sources of PAHs in the study area. Risk analysis showed that the mean and 90 % probability estimated inhalation ILCRs were 7.85 × 10⁻⁶ and 16.78 × 10⁻⁶, respectively. Results of a sensitivity analysis indicated that BaP concentration and cancer slope factor (CSF) contributed most to effect on ILCR mean.