This study was conducted to investigate the risk assessment of Cu, Zn, Ni and Pb in fine road dust colloid samples. 60 samples of road dust were collected from 60 urban locations in Hamedan city with 6 different traffic characteristics on May 2013. The samples were analyzed for four heavy metals using ICP MS. The average concentration values of the Cu, Zn, Ni and Pb were found 60.8, 190, 95.9 and 168 mg kg-1 respectively, which were generally lower than the limited values except Copper. The concentrations of Cu, Zn and Pb in road dusts indicated that there was a considerable Cu, Zn and Pb pollution, which mainly originated from traffic and industrial activities. The pollution level was estimated based on the pollution index (PI). The values of PI were in the following order: Cu>Pb>Zn>Ni. The assessment results of PI also support Pb, Zn and Cu in road dusts presented serious pollution. The pollution level is expected to increase due to rapid urbanization of the area.
