Comparison of air pollution exposure for five commuting modes in Sydney - car, train, bus, bicycle and walking

Issue addressed: International studies have consistently found that exposure to air pollutants is higher inside cars than outside. However, few studies have compared personal exposure to air pollutants by travel mode focusing on usual travel patterns. Objectives: To compare the exposure to benzene, toluene, ethylbenzene and xylene (BTEX) and nitrogen dioxide (NO 2 ) for commuters in central Sydney for five different commuting modes. Methods: Forty-four volunteers were recruited into one of five travel mode groups: car, train, bus, bicycle and walking. Each participant travelled for at least 30 minutes by their usual mode of travel to the area around Royal Prince Alfred Hospital, in central Sydney. Each participant wore BTEX and NO 2 passive sampling apparatus during their travel to and from work for two weeks, following specific instructions to measure personal exposure. Results: The highest pollutant levels for all four BTEX pollutants were found for car commuters. Train commuters recorded the lowest pollutant levels for all four BTEX pollutants and NO 2 , and these levels were significantly lower than that for car commuters. Commuting by bus recorded the highest levels for NO 2 . Walking and cycling commuters had significantly lower levels of exposure to benzene compared with car commuters and significantly lower levels of NO 2 than bus commuters. Conclusions: The results of this study are consistent with the findings of studies in other cities and found elevated levels of exposure to motor vehicle-related pollutants in roadway microenvironments. Strategies that encourage commuting by train, walking and cycling should be supported as this reduces population exposure to motor vehicle-related pollutants.