Ambient levels of BTEX at roadside in northern Iraq and its relationship with traffic volume.

Abstract

Among the mono-aromatic volatile organic compounds, benzene, toluene, ethylbenzene and xylene (BTEX) have occupied a large area in air pollution studies due to their carcinogenic and non-carcinogenic effect. In this study, a station was used to monitor BTEX concentrations at roadside in urban area at Mosul city along a year, with traffic volume and meteorological factors measurement. The annual mean of benzene was 12 µg/m3, which is more than twofolds of the standard European Union level of 5 µg/m3. In addition, 87.4% of the measured values in summer was higher than the standard level at roadside. Benzene was dominant in spring and summer among BTEX species, while the dominance changed to ethylbenzene in autumn and winter. Besides, benzene, toluene, ethylbenzene and o-xylene showed significant seasonal variation. BTEX and benzene concentrations increased as the number of vehicles on gasoline and diesel increased. In contrast, toluene and ethylbenzene were more affected with number of vehicles on diesel. On the other hand, the weak significant correlations among BTEX species and high T/B ratio indicate the difference in fuel types used and the existence of additional sources of BTEX emission with the vehicular exhausts. These results can be utilized in determining the control strategy in air quality management in Mosul city.