investigating the non-carcinogenic risk and hazard quotient of heavy metals in high-traffic districts of tehran metropolis, iran

Background: this study aimed to investigate the concentrations of heavy metals bound toairborne particulate matter (pm) in high-traffic districts of tehran, iran, and to determine thecarcinogenic risk and hazard quotient (hq) of these metals using a descriptive-applied method.methods: six indoor/outdoor stations were established in three high-traffic districts of tehran.each station was sampled with six replicates in winter 2018 (36 samples in total). after extractingthe metals from fiberglass filters by acid digestion based on the astm (the american societyfor testing and materials method), the concentrations of heavy metals were determined by aninductively coupled plasma (icp-oes) device. the human health risk was evaluated according tothe us epa (environmental protection agency) standard method. the obtained data were analyzedby the spearman correlation and multivariate analysis of variance (manova) in spss.results: districts 2, 3, and then 15 were the most high-traffic areas of tehran in descending order. averageheavy metal concentrations were detected in order of al>fe>pb>mn>cu>zn>cr>as>ni>cd.also, the heavy metals concentrations were significantly different between indoor and outdoorenvironments. the correlations between heavy metal concentrations, carcinogenic risk, and hq weresignificant in all three districts (p<0.05). mean carcinogenic risk variables, hq levels, and heavymetal concentrations in all three regions were in order of districts 15>2>3 and outdoors>indoors.conclusion: based on the results, serious measures are recommended to control trafficcongestion in tehran to prevent cancer risk and other health hazards caused by heavy metalbonded tsp (total suspended particulate matter).