Study of contamination, sources and health risk of potentially toxic elements in dusts of Tehran’s elementary schools

Concerns about dust contamination with potentially toxic elements are especially important in environments such as schools (particularly elementary schools) because children are more vulnerable to contaminants than adults. Therefore, due to the diversity of air pollution sources in Tehran, the present study was conducted to determine the severity of pollution, origin and health risk assessment of some potentially toxic elements in the dust of elementary schools in three districts of Tehran. For this purpose, 27 dust samples were collected from the indoor and outdoor areas of schools, and the concentration of elements was measured by induced coupled plasma mass spectrometer (ICP-MS). Calculation of different geochemical indices showed that the four elements Cu, Zn, Sb and Pb have the highest enrichment and pollution compared to other elements. The results of calculating the health risk index revealed that As, Cu, Ni, Pb and Zn have similar hazard quotient (HQ) values in children and adults. Also, the health risk of exposure to Cr and Mn through dermal contact is higher in adults than in children, and the total hazard index (HI) of all elements in children is higher than in adults. Among the studied elements, two elements, lead and chromium, threaten the health of children more than others. Based on principal component analysis and positive matrix factorization (PMF) model, three geogenic, traffic and mix sources were identified for different elements. Pb, Zn, Cu and Cd were considered as indicators of traffic origin. The results of this study reveal the need for special attention to students' health.