Abstract:
This study evaluated spatial and temporal changes in Benzene, Toluene, Ethylbenzene, and
Xylene (BTEX) levels of ambient air in high-traffic highways of Tehran (Iran)individually during four
seasons, 2021-2022. High High-traffic areas were selected in the study area. According to the
National Institute for Occupational Safety and Health method 1501, air samples were collected from
10 stations by personal air sampling pump and charcoal sorbent, extracted by carbon disulfide, and
analyzed by gas chromatography-flame ionization detector. MATLAB software was used for spatial
modeling of BTEX level changes and GIS software for zoning distribution of parameter level changes.
The highest BTEX level was in the northwest regions, and the maximum pollution corresponded to
autumn, especially the concentrations of benzene and toluene compounds, which were higher than
the ambient air quality standards of Iran and the US Environmental Protection Agency. The highest
amount of benzene was seen in the autumn season with an average value of 34.51 ppb and in winter with an average value of 22.83 ppb, and the lowest amount of benzene was in the summer season with 22.84 ppb. The highest amount of toluene was 427.76 ppb in autumn and the lowest amount was 80.13 ppb in spring. The highest amount of xylene concentration with an average of 187.80 ppb was related to the summer season and the lowest amount was 0 ppb in autumn. The highest amount of ethylbenzene in summer was 95.67ppb. To conclude, there is a need to diminish and control the level of BTEX pollutants caused by transportation sources in Tehran.