Exposure to benzene may adversely affect human health through non-carcinogenic and carcinogenic effects, especially leukemia. Benzene in gasoline is evaporated in the air around gas stations, and workers in gas stations are exposed to such vapors. Risk assessment is among the crucial strategies to identify and control exposure to chemicals. This study determined exposure, the non-cancer risk, and the cancer hazard of exposure of gas station workers to benzene. Benzene concentration at gas stations in Tehran was evaluated using AERMOD 1 . Cancer and non-cancer risks of benzene were then assessed by the IRIS 2 method. The highest and lowest benzene concentrations in the workers' respiratory air in the gas station were 79.47 and 9.63 µg/m 3 , respectively. In the worst case, the benzene inhalation risk (IR) was 5.26 per 100000 people. The hazard quotient (HQ) of benzene was more than one (HQ>1). According to the results, the benzene-related health risk is unacceptable for most workers. Increasing and decreasing benzene's IR and HQ depend on the operating capacity and loading times of tanks in each gas station.