Abstarct: Street dust is one of the most important indicators reflecting the pollution situation in urban environments. These particles carry carbon monoxide, such as polycyclic aromatic hydrocarbons (PAHs), which have adverse environmental effects and impacts health of the city's inhabitants. The purpose of this study was to evaluate the concentration and source of these compounds and their effects on human health. For this purpose, ۱۳ dust samples were collected. PAHs levels in dust samples were determined by GC-MS. To determine the possible origin of PAHs, aromatic chemical ratios were calculated. All ۱۶ environmentally important compounds were identified in the samples. PAHs levels ranged ۸۸.۴ ppb to ۷۷۱.۰۲ ppb. The ∑PAH / ∑COMB value was between ۰.۵ ppb and ۰.۸ ppb. The ratio of Ant / (Ant + Phe) was found between ppb ۰.۰۸ to ۰.۹۸ ppb, BaA / (BaA + CRY) between ppb ۰.۳۳ to ppb ۰.۵۶ and IND / (IND + BGP) between ۰.۱۳ ppb ۰.۸ ppb. In this study, it was revealed that the pyrogenic source is the principal source of PAHs in street dusts. Benzoylpyrene was identified as the most common PAH cancer in all of the sampling stations at different concentrations. The results of this study showed that the metropolitan area of Karaj is strongly influenced by the type and composition of PAHs because of its urban location, increasing population and traffic intensity.