Background: Street dust is an environmental medium with complex composition in urban environment. Heavy metals remain in urban dust for a long time and re-suspended in the atmosphere. This study aimed to evaluate the metal richness and degree of contamination in Tehran street dust. 
Methods: Dust samples were collected from nine locations in Tehran in 2018. Heavy metals (Cd, Cr, Pb, Zn, Fe, and Al) were analyzed in street dust using ICP-MS. Metal richness and degree of contamination were determined using Enrichment Factor (EF), Geoaccumulation Index (Igeo), degree of Contamination (Cd) and modified degree of contamination (mCd). Pearson correlation (PC) and Hierarchical cluster analysis (HCA) were also used for analysis.
Results: The mean concentration trend of elements was as Al (53486.54)> Fe (46535.07)> Zn (638.14)> Pb (200.33)> Cr (111.94), Cd (0.49) mg/kg. The highest metal enrichment was due to Pb and Zn. The geoaccumulation index also showed that Cd and Pb had the highest values. Degree of contamination indices also showed high levels of contamination in street dust. Significant correlation was observed between Zn-Cr-Pb and Pb-Cd. Significant negative correlation was also observed between relative humidity-Pb-Zn. Elemental clustering also showed that Pb, Zn, Cr, and Cd had anthropogenic sources and Fe and Al had natural sources of diffusion.    
Conclusion: The results of this study showed that the street dust of Tehran is highly polluted. Therefore, this environmental medium can have significant negative effects. Therefore, continuous monitoring of street dust is essential.