title: Commuter exposure to BTEX in public transportation modes in Bangkok, Thailand.
abstract: 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 microg/m3 in A/C bus; 37.1, 174, 14.7, and 55.4 microg/m3 in non-A/C bus; 2.0, 36.9, 0.5, and 0.5 Cig/m3 in sky train; and 3.1, 58.5, 0.5, and 6.2 microg/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.affiliation: Faculty of Engineering, Mahasarakham University, Kantarawichai District, Mahasarakham 44150, Thailand. maneerat.o@msu.ac.th
authors.forename: Maneerat
authors.initials: M
authors.lastname: Ongwandee
authors.forename: Orathai
authors.initials: O
authors.lastname: Chavalparit
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry*; D002947:Cities; D004781:Environmental Exposure; D006801:Humans; D018986:Motor Vehicles; D013785:Thailand; D013997:Time Factors; D014050:Toluene / Q000737:chemistry*; D001335:Vehicle Emissions / Q000032:analysis; D055549:Volatile Organic Compounds / Q000737:chemistry; D014992:Xylenes / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D001555:Benzene Derivatives; D001335:Vehicle Emissions; D055549:Volatile Organic Compounds; D014992:Xylenes; D014050:Toluene; D001554:Benzene; C004912:ethylbenzene