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Commuter exposure to BTEX in public transportation modes in Bangkok, Thailand

2012-09-12 1169

Commuter exposure to BTEX in public transportation modes in Bangkok, Thailand

Measurements and monitoring of volatile organic compounds (VOCs) have been conducted in the metropolitan Bangkok. However, in-vehicle levels of VOCs are still lacking. This study investigated VOCs concentrations in four public transportation modes in Bangkok, Thailand during two rush hour periods (7:00?9:00 a.m. and 4:00?7:00 p.m.). The four modes included an air-conditioned bus (A/C bus), non-air-conditioned bus (non-A/C bus), electric sky train, and a passenger boat traveling along the canal. Comparison among three important bus routes was also studied. In-vehicle air samples were collected using charcoal sorbent tubes and then analyzed by a gas chromatography-mass spectrometer. Results showed that the transportation modes significantly influenced the abundance of in-vehicle benzene, toluene, ethylbenzene, and m,p-xylene (BTEX). Median concentrations of BTEX were 11.7, 103, 11.7, and 42.8 ?g/m3 in A/C bus; 37.1, 174, 14.7, and 55.4 ?g/m3 in non-A/C bus; 2.0, 36.9, 0.5, and 0.5 ?g/m3 in sky train; and 3.1, 58.5, 0.5, and 6.2 ?g/m3 in boat, respectively. Wilcoxon rank sum test indicated that toluene and m,p-xylene in the sky trains were statistically lower than that in the other three modes at a p-value of 0.05. There were statistical differences in TEX concentrations among the bus routes in the non-A/C buses. In addition, the benzene to toluene ratios implied that tail-pipe emissions were important contributor to the abundance of in-vehicle VOCs.

Authors : Maneerat Ongwandee,Orathai Chavalparit
Book /Journal Title : Journal of Environmental Sciences ;2010 / 22 / 397-404

 

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