Main Article Content
This study investigated concentrations of volatile organic compounds (VOCs) 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 San Saeb canal. Five studied routes were Paholyothin Road, Sukhumvit Road, Petchburi-Ramkhamheang Road, sky train route, and boat route. In-vehicle air samples were collected within the commuter’s breathing zone using charcoal sorbent tubes, desorbed by carbon disulfide, and then analyzed by a gas chromatography-mass spectrometer. Results show that the transportation modes significantly influenced the abundance of in-vehicle benzene, toluene, ethybenzene, and m,p-xylene (BTEX). Mean concentrations of BTEX were 53.8, 210, 14.6 and 46.0 µg m-3 in A/C bus; 66.1, 200, 18.2 and 74.1 µg m-3 in non-A/C bus; 13.2, 39.5, 0.50 and 0.97 µg m-3 in sky train; and 60.0, 73.7, 2.6 and 7.3 µg m-3 in boat, respectively. Wilcoxon rank sum test indicated that toluene and m,p-xylene in the sky trains were statistically lower than in the other three modes at a p-value of 0.05. The Benzene to toluene (B/T) ratios implied that tail-pipe emissions from gasoline-used vehicles were important contributor to the abundance of in A/C bus VOCs. Furthermore, the lifetime cancer and non-cancer risks for commuters exposed to BTEX were estimated. Results show that all transportation modes had a lifetime cancer risk between 2×10-6 and 2×10-5, while non-cancer risks were below the US EPA reference levels.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Published articles are under the copyright of the journal. Partially or totally publication of an article elsewhere is possible only after the consent from the editors.