On the nature of heavy metals in PM₁₀ for an urban desert city in the Middle East: Shiraz, Iran

This study investigated the concentrations of suspended particulate matter £ 10 µm in diameter (PM₁₀) and their heavy metal content, including cadmium, lead, chromium, zinc, nickel, aluminum, and iron, in ambient air in the Middle East: Shiraz, Iran. The Crystal Ball 7.3 software package was used to assess carcinogenic and non-carcinogenic health effects due to heavy metal exposure. The mean concentrations of heavy metals increased in the following order: Fe > Al > Zn > Pb > Cr > Ni > Cd. Meanwhile, the average concentrations of PM₁₀ decreased during the same time frame. When comparing PM₁₀ on various days of the week in Iran, including holidays (Thursday and Friday), two days after holidays (Saturday and Sunday), and other days (Monday, Tuesday and Wednesday), the concentrations were higher two days after the holidays as compared to other days of the week (p < 0.05). The excess lifetime cancer risk (ELCR) for Cr, especially for children was 1.20 × 10⁻², which surpassed suggested EPA levels. The non-carcinogenic values of heavy metals for children were significantly higher than those for adults for three pathways. The results indicate that children usually had more exposure to heavy metals associated with PM₁₀ as compared to adults.