Abstract

Benzene, toluene, ethyl benzene and xylene are among the volatile organic compounds with similar physical and chemical properties. BTEX present in gas enters the urban atmosphere through vapourization from the gas in gas stations. Hence, the gas station workers are exposed to these hazardous vapours. The purpose of this study was to optimize the conditions of BTEX extraction from air samples using the solid phase microextraction (SPME) and measure the rate of pollution in Yazd gas stations in central region of Iran. This was a descriptive, cross-sectional study in which 13 gas stations were selected randomly. Air sampling was done in 35 gas stations at the end of the morning shift. The air samples were collected with Tedlar gas sampling bags and analyzed using SPME fibre via gas chromatography with FDI. The findings of the study showed that most of the area under curve belonged to the fibre polydimethyl cyclohexan-carboxen (PDMS/CAR) compared to other two types of fibre. Also, the extraction time and sample recycling time from the fibre were determined to be 1 and 3 min, respectively. The mean concentration of benzene, toluene, ethyl benzene and xylene were 1932 ± 807 μg/m3, 667 ± 405 μg/m3, 148 ± 89 μg/m3 and 340 ± 216 μg/m3, respectively. The mean concentration of air benzene was higher than the permissible standard rate recommended by the National Technical Committee of Occupational Health (0.5 PPM), while the concentrations of toluene, ethyl benzene and xylene were less than the permissible limits.