analysis of btex in ambient air using gas chromatography-flame ionization detector to assess health risks

The united states environmental protection agency (usepa) classified benzene, toluene, ethylbenzene, and xylene (btex) as a hazardous air pollutant (haps). this study aimed to investigate the spatiotemporal variations of btex and its health risks in the ambient air of kerman, iran. sampling was actively done using the niosh-1501 standard method in 2022. btex compounds were analyzed in the laboratory using a gas chromatography flame ionization detector (gc-fid). the effect of btex on tropospheric ozone production has been investigated through the calculation of the ozone formation potential (ofp). the average btex concentrations during winter and summer were analyzed using gc-fid, resulting in the following order: xylene > toluene > benzene > ethylbenzene. the average total concentration of benzene, toluene, ethylbenzene, and xylene compounds was 29.87, 103.34, 16.89, and 109.44 µg m-3, respectively. in general, the concentration of btex in winter was higher than in summer. due to the average ofp, total btex compounds were obtained to be 908.80 µg m-3  and 376.48 µg m-3 in winter and summer, respectively. the non-cancer risk was at a safe level of less than one (hq<1) in both seasons. the carcinogenicity of benzene in summer and winter was found to be 7.55×10-5 and 1.76×10-4, which is more than the recommended limit of epa.  motor vehicles were kerman’s main potential sources of btex  in the study period.  based on the results, it can be concluded that motor vehicles were the main potential sources of btex in kerman during the study period. therefore, based on the btex analysis, gasoline control, green space development, and public transportation can be suggested to diminish the number of btexs in kerman city.