Abstract
Concern for health hazards from volatile organic compounds from the Map Ta Phut Petrochemical Estate has resulted in a study of the concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) species in the ambient air surrounding and within the industrial complex. Ambient air samples have been collected at numerous locations during the dry (22-28 February), the semi-wet (29 April-5 May) and the wet season (19-25 June) in 2002. Collection was via personal pumps onto charcoal adsorbent tubes. The samples were extracted and analysed by gas chromatography equipped with a flame ionization detector (GC/FID). The data have been analysed statistically and comparisons made between levels from upwind, downwind and within the complex. For daytime concentrations, the median and maximum at two upwind monitoring sites were respectively 3.9 and 17.7 μg/m3 for benzene, and 2.1 and 8.6 μg/m3 for toluene. These data can be compared with two downwind monitoring sites where the results were 5.2 and 26.5 μg/m3 for benzene, and 6.0 and 370.5 μg/m3 for toluene. The variability observed across the data set highlights the importance of (1) source type and location, (2) fugitive emissions and episodal events, and (3) the meteorological conditions. The mean benzene concentrations at any site did not exceed the WHO annual air quality standards, 5 ppbv (16.2 μg/m3). The levels of BTEX measured have been found to be comparable to those from studies elsewhere. Emissions from the Petrochemical complex including the oil refineries, and to a lesser extent those from motor vehicles, are the dominant contributors to the BTEX ambient concentrations.
Keywords
BTEX;