Carcinogenic Risks of Airborne PAHs in Iran: A Comprehensive Risk Assessment Study

This study assesses the carcinogenic risks associated with polycyclic aromatic hydrocarbons (PAHs) in the air and their impact on human health across urban and rural areas in Iran. Polycyclic aromatic hydrocarbons (PAHs) were analyzed in both gaseous and particulate phases using gas chromatography-mass spectrometry (GC-MS). The findings indicated that PAH concentrations frequently exceeded the safety thresholds established by the World Health Organization (WHO), with high molecular weight PAHs, particularly benzo[a]pyrene (BaP), identified as the primary contributors to cancer risks.Seasonal fluctuations demonstrated markedly elevated PAH concentrations during the colder months, predominantly attributable to augmented emissions from domestic heating, vehicular exhaust, and industrial operations. Source apportionment and diagnostic ratio analyses identified diesel vehicles, biomass burning, and fossil fuel combustion as the primary sources of PAH pollution.The results of the health risk assessments, expressed as toxic equivalency concentrations (BaPeq) and incremental lifetime cancer risk (ILCR), indicated elevated risks, particularly among vulnerable groups such as children and economically disadvantaged households. The concentration of PAHs indoors was found to be influenced by poor ventilation systems and the presence of equipment such as printers and copiers. In contrast, outdoor concentrations were highest in regions with heavy traffic and industrial activity.These findings underscore the imperative for targeted mitigation strategies to reduce PAH exposure, including the transition to cleaner energy sources, the improvement of ventilation systems, and the enforcement of more rigorous emission controls. This study provides a comprehensive assessment of PAH pollution and its associated health implications, offering essential data to inform the development of regulatory policies and public health interventions aimed at minimizing carcinogenic risks.