Ambient Air Concentrations of Benzene, Toluene, Ethylbenzene and Xylene in Bangkok, Thailand during April–August in 2007

Benzene, toluene, ethylbenzene and m-, p-, and o-xylene, the most influential aromatic volatile organic compounds (VOCs), were measured in Bangkok, Thailand, one of the most rapidly developing urban areas in Southern East Asia. The purpose of this study is to characterize the ambient air quality with respect to above mentioned aromatic compounds. The data were monitored in ten sites which cover roadside area, residential area and background area. Canister technique was used to obtain air sample at 24 hour interval per a month during April-August in 2007. GC/MS with three stage preconcentrator was used to analyze these samples. The average concentrations of benzene, toluene, ethylbenzene m-, p-xylene and o-xylene are 5.8, 36.1, 4.1, 11.0 and 3.7 μg/m3, respectively. They were observed to be distributed in a log-normal form. Moreover, o-xylene and m,p-xylene exhibited a very good correlation (r=0.976). The slope of the regression equation between them was 3.07 which consisted with a previous reported value. The average ratio of toluene to benzene was 6.4 in April, May June and August. This value was comparable to the ones measured in other Asian cities. Two types of statistical analyses, cluster and factor analyses, were applied to the data in this study. Well characterization was made to understand the air quality of Bangkok area.