| Summary: | 碩士 === 國立臺灣大學 === 職業醫學與工業衛生研究所 === 93 === Objective: This study is designed to characterize NC0.01-0.1(number concentrations of ultrafine particles with size between 10nm ~ 100 nm) at public transportation stations, including mass rapid transit (MRT), train, and bus stations, in Taipei.
Method: The number concentrations and size distribution of PM with size range 9.8-874.5 nm(Total number concentrations) were measured by a scanning mobility particle sizer(SMPS) at four bus stations, three train stations, and four mass rapid(MRT) stations in Taipei from January 17th to March 18th, 2005. The sampled period at each station is 17.5 hours. We focused our study on two particle sizes, i.e. NC0.01-0.1 and NC0.01-0.05(number concentrations of ultrafine particles with size between 10nm ~ 50 nm). NC0.01-0.1 exposures of public transportation users were estimated by combining NC0.01-0.1 concentrations at stations and commuters’ waiting time, and ventilation rate together.
Result: Hourly average number concentrations of NC0.01-0.1 at bus, train and MRT stations were 12.8 × 104 cm-3, 6.38 × 104cm-3 and 3.63 × 104cm-3, respectively. For train and MRT stations, the number concentrations of NC0.01-0.1 at indoors were higher than those outdoors. Moreover, the number concentrations at MRT and bus stations in rush hours were higher than those in non-rush hours.We found the same results for NC0.01-0.05. The percentage of number concentrations of accounted for NC0.01-0.05 about 78.5% at bus stations, 46.6% at train stations, and 47.1% at MRT stations. Adult commuters’ annual NC0.01-0.1 exposures were 1.77 × 1013counts at bus stations, 5.76 × 1012counts at train stations, and 2.84 × 1012counts at MRT stations.
Conclusion: The NC0.01-0.1 concentrations in public transportation stations varied by the distance between the stations and on-road vehicle emission sources in Taipei. The NC0.01-0.1 concentrations in bus stations were significantly higher than those in train and MRT stations. Accordingly, bus users annual NC0.01-0.1 exposures were 1.19 × 1013counts higher than train users, and 1.48 × 1013counts higher than MRT users.
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