Gas as an organic chemical compound is highly volatile in atmosphere. These volatile compounds are found in the human body in different ways. For this reason, a research on determining the concentration of organic hydrocarbon compounds benzene, xylene carried out. Furthermore, their impacts on air quality in the fuel supply in two season of cold season (winter) and warm (summer), two locations and three different time (morning, evening, night), is the refueling stations of vehicles and a distance of four feet from the refueling stations in Tehran, is investigated. The absorbent of NIOSH -1501 and SKC 226-01 were used for the study. The results showed that the amount of benzene in refueling stations of vehicles and a distance of four feet from the refueling stations in the evening was higher than the two other time measured, in the winter, 1.11 and 0.22 ppm respectively. However, in summer, benzene was high at night besides the evening as well. Thus, benzene at studied station could threaten the health of the staffs. In terms of xylene, the pattern follows the same trend as benzene. However, the amount of xylene in the workplace and the surrounding environment was less than the determined limit (100 ppm). Consequently, the xylene was less than the amount of dangerous and positioned for the health of the staffs and other people in the areas.