In-Vehicle Exposures to Particulate Air Pollution in Canadian Metropolitan Areas: The Urban Transportation Exposure Study

摘要

Commuters may be exposed to increased levels of traffic-related air pollution owing to close proximity to traffic-emissions. We collected in-vehicle and roof-top air pollution measurements over 238 commutes in Montreal, Toronto, and Vancouver, Canada between 2010 and 2013. Voice recordings were used to collect real-time information on traffic density and the presence of diesel vehicles and multivariable linear regression models were used to estimate the impact of these factors on in-vehide pollutant concentrations (and indoor/outdoor ratios) along with parameters for road type, land use, and meteorology. In-vehicle PM_(2.5) and NO_2 concentrations consistently exceeded regional outdoor levels and each unit increase in the rate of encountering diesel vehicles (count/min) was assodated with substantial increases (＞100%) in in-vehide concentrations of ultrafine partides (UFPs), black carbon, and PM_(2.5) as well as strong increases (＞15%) in indoor/outdoor ratios. A model based on meteorology and the length of highway roads within a 500 m buffer explained 5396 of the variation in in-vehide UFPs; however, models for PM_(2.5) (R~2 = 0.24) and black carbon (R~2 = 0.30) did not perform as well. Our findings suggest that vehicle commuters experience increased exposure to air pollutants and that traffic characteristics, land use, road types, and meteorology are important determinants of these exposures.