Spatio-Temporal Distribution of PM[sub.2.5] and PM[sub.10] Concentrations and Assessment of Public Health Risk in the Three Most Polluted Provinces of Iran

This study examines the spatio-temporal variations of ambient air pollution from fine particulates below 2.5 µm (PM[sub.2.5]) and particulate matter below 10 µm (PM[sub.10]) in three of the most polluted provinces in Iran, namely Tehran, Isfahan, and Khuzestan, over a 6-year period (2016–2021). The results reveal distinct patterns of PM[sub.10] and PM[sub.2.5] concentrations since in Tehran, the highest PM[sub.10] and PM[sub.2.5] levels occur in winter, while PM[sub.2.5] is lowest from March to May. Khuzestan experiences the highest pollution levels in summer due to dust storms, while Isfahan exhibits pollution levels and annual patterns similar to Tehran. Strong correlations are observed between PM[sub.10] and PM[sub.2.5] concentrations at stations in Tehran and Khuzestan Provinces, suggesting common sources and variation in both coarse and fine PM, with average PM[sub.2.5]/PM[sub.10] ratios of 0.39–0.42, suggesting the dominance of dust. Furthermore, the analysis identifies the role of atmospheric stability, wind speed, and dust storms in controlling the PM levels in the three provinces. Lifetime cancer risks have been identified as unacceptably high, exceeding the threshold limit of 10[sup.−4], while Hazard Quotient (HQ) values above 1 indicate a high non-carcinogenic potential risk, particularly at stations in Khuzestan Province. The Excess Lifetime Cancer Risk (ELCR) values for PM[sub.2.5] exposure in the most populated Tehran Province range from 139.4 × 10[sup.−6] to 263.2 × 10[sup.−6], underscoring significant cancer risks across various monitoring sites. This study emphasizes the urgent need for targeted pollution control measures in each province to effectively mitigate the adverse health effects associated with high PM concentrations.