Evaluation of Concentration of BTEX and PAHs and Its Effective Parameters in Gasoline Fuel Distribution Stations: A Case Study in Single Purpose Stations in Karaj

Background and Objective: One of the sources of emissions of BTEX and PAHs is fuel distribution stations in cities. This study aimed to evaluate and monitor the concentrations of BTEX and PAHs and the parameters affecting them in gasoline distribution stations in Karaj. Materials and Methods: Sampling was performed to determine the concentration of BTEX and PAHs and the parameters affecting it in the winter of 2020 from 5 fuel distribution stations in the morning, noon, evening, and night at intervals of zero, 50, and 100 meters. The standard method 1501 provided by the National Institute of Occupational Safety and Health was used to measure the concentration of BTEX compounds, and the TO-17 EPA standard method was used to measure PAHs. Dwyer measured temperature and humidity at the sampling points. Results: Most of the BTEX concentration values ​​were related to the fuel station in the city center. The concentrations of benzene, toluene, ethylbenzene, and xylene at zero distance from the source in the morning were 133, 311, 207, and 266 μg.m-3, respectively (maximum concentration compared to other times). The minimum concentration was determined at night. The benzene concentration in all the studied sites was higher than the environmental permissible limits. There was a significant relationship between BTEX concentration and site location, the time interval during the day, distance from the site, and psychometric parameters such as temperature and humidity. Conclusion: Benzene concentration was higher than the environmental allowable limit in all stations. Climatic parameters and the variables of population density, location, distance from the place of release, and time interval were effective parameters in the exposure rate. Therefore, by controlling the above variables, a practical step can be taken to plan control measures and reduce the emission of these pollutants. Also, the present study's findings can help predict daily changes in the concentration of these compounds in different parts of the city and determine the points and times with a high probability of exposure.