Occurrence, Probable Source, and Health Risk Assessment of Benzene, Toluene, Ethylbenzene, and Xylene Compounds in Ambient Urban Atmosphere in Ahvaz, Iran

The benzene, toluene, ethylbenzene, and xylene (BTEX) compounds are the most abundant volatile organic compounds in the urban atmosphere. This study aimed to investigate and monitor the ambient BTEX compounds in Ahvaz, Iran.

The atmospheric concentrations of the BTEX were measured using the Air Quality Monitoring Station in the center of Ahvaz. Hourly mean concentration data of the BTEX compounds from March 21, 2017, until November 21, 2017, were obtained from the environmental protection organization of Khuzestan province.

Mean concentrations of the BTEX compounds were 0.80±0.04, 2.55±0.10, 0.54±0.03, and 1.26±0.07 µg/m3, respectively, and these concentrations were lower in the summer, compared to other seasons. A significant relationship between benzene and other BTEX compounds indicates that BTEX release from certain sources, such as gasoline vehicles. Moreover, the mean toluene/benzene ratio was estimated at 3.29±0.84, and this ratio shows that the highest concentrations of pollutant emissions were emitted from the activity traffic. Carcinogen risk assessment of Ahvazi people exposure to benzene showed that the mean cancer risk value for benzene exposure was 0.89×10−6, which was lower than the unit cancer risk value (i.e., 1×10-6). Hazard quotient's calculation showed that the mean non-carcinogenic risk values for exposure to BTEX compounds were 3.84, 0.074, 0.077, and 1.76, respectively. The mean hazard index (HI) for exposure to BTEX compounds was 5.75, which was considerably higher than the unit value of 1.

Based on the findings, the necessity of controlling BTEX emissions, especially benzene and identifying the sources of these compounds can be a useful tool for the management of connected control strategies.