Investigation of volatile organic compounds inside five public transports and determination of health risk exposures in Hong Kong

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Investigation of volatile organic compounds inside five public transports and determination of health risk exposures in Hong Kong

 

Author: Ko, Wai-ying Winnie
Title: Investigation of volatile organic compounds inside five public transports and determination of health risk exposures in Hong Kong
Degree: M.Sc.
Year: 2001
Subject: Volatile organic compounds -- Health aspects -- China -- Hong Kong
Indoor air pollution -- China -- Hong Kong
Transportation -- China -- Hong Kong
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Civil and Structural Engineering
Pages: 1 v. (various pagings) : col. ill., 1 col. map ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1611633
URI: http://theses.lib.polyu.edu.hk/handle/200/2577
Abstract: Indoor air pollution has now become a matter of increasing public concern. On average, most people spend about 70% indoor of our time staying indoor. Apart from the concern on the air quality inside offices and public indoor areas, air quality inside vehicles is becoming a hot topic due to the necessity of travelling. Many researches have been done in North America, Europe and Asian countries. The aim of this project is to investigate the volatile organic compounds (VOCs) inside five different public transports and determine the health risk exposure on passengers and drivers. Five public transports including bus, public light bus and three railways (Mass Transit Railway (MTR), Kowloon Canton Railway (KCR) and Light Rail Transit (LRT)), were selected for the indoor air quality investigation. Bus, public light bus and MTR are running in urban area, KCR is running between urban and rural areas and LRT is running in rural area. Air samplings were taken during non-peak and peak periods in weekdays. Benzene, toluene, ethylbenzene and xylenes (BTEX) are major VOCs inside public transports. The study identified that major source of VOCs is vehicular emissions on road and BTEX are major components of vehicular emissions and evaporative emissions. The study also indicated that toluene was the most abundant VOC inside public transports as toluene was a common used solvent of fuel. Highest BTEX ratio was identified in MTR which ratios are 1:17:2:5 and 1:20:2:3 during non-peak and peak periods. In addition, the benzene measured inside bus, PLB and MTR during non-peak period was higher than that measured during peak period due to high traffic flow in urban area either in non-peak period or peak period. Compared with the ambient benzene concentration, the concentrations inside bus, PLB and MTR are higher during non-peak and peak periods while the concentrations inside LRT and KCR are lower during non-peak period and higher during peak period. Compared with the benzene inside bus, PLB and MTR, the concentration inside PLB is highest during peak period due to the older operation year and worst maintenance. Bus/MTR ratio of benzene was 1.3 and 2 during non-peak and peak periods due to the same route of car and train. In addition, the BTEX concentration inside bus was higher than that in KCR and LRT 3.5 times due to higher on-road traffic flows and the shortest separation from the heavy trafficked road. Benzene is classified as carcinogenic in accordance with the risk guidelines of the US Environmental Protection Agency (US EPA). The healrth risk was calculated by two approaches in this study: unit risk factor and potency factor. With unit risk factor approach, high health risk was estimated in PLB which the upper bound health risks were 8.6x10-5 and 8.1x10-5 during non-peak and peak periods respectively. With using potency factor approach, highest lifetime risk were estimated in bus for passenger and in PLB for driver. For toluene, ethylbenzene and xylenes, they are classified as non-carcinogenic air pollutants, however, they will also cause chronic effect when prolonged exposure. In the study, the concentration of toluene, ethylbenzene and xylenes are measured to be 19%, 0.7% and 1.6% of their criterion respectively.

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