Concentration, sources and human health risk of heavy metals and polycyclic aromatic hydrocarbons bound PM_2.5 ambient air, Tehran, Iran

The exposure to heavy metals and polycyclic aromatic hydrocarbons (PAHs) bound to particulate matter 2.5 (PM_2.5) ambient air can result in some adverse health effect. In the current study, PM_2.5 ambient air of Tehran metropolitan, Iran, was characterized by the aid of scanning electron microscope and energy-dispersive X-ray techniques. Also, the human health risk of heavy metals and PAHs bound PM_2.5 for adults and children was assessed using the Monte Carlo simulation method. According to our findings, a size range of 0.97–2.46 μm with an average diameter of 1.56 μm for PM_2.5 was noted. The average concentration of PM_2.5 in ambient air (8.29E+04 ± 2.94E+04 ng m⁻³) significantly (p < 0.05) was suppressed the national (2.50E+04 ng m⁻³), World Health Organization (2.50E+04 ng m⁻³) and Environmental Protection Agency (3.50E+04 ng m⁻³) standard limits. The rank order of heavy metals bound PM_2.5 was determined as Al > Cu > Cd > Cr > Pb > Ni > Fe > Mn. The maximum concentration among 16 PAHs compounds investigated was correlated with Phenanthrene. Considering the principal component analysis, the main source of heavy metals (Ni, Pb and Cr) is vehicle combustion. Moreover, the rank order of exposure pathways based on their health risk was ingestion > inhalation > dermal contact. Moreover, the significant health risks for Tehran residents due to heavy metals bound PM_2.5 [target hazard quotient > 1; carcinogenic risk > 1.00E−06)] were noted based on the health risk assessment. Excessive carcinogenic risk (ECR) of PAHs bound PM_2.5 was 4.16E−07 that demonstrated that there is no considerable risk (ECR < 1.00E−06).