Near-Road Air Pollution Pilot Study Final Report

Abstract

Vehicles emit a complex mixture of air pollutants that can reach wide areas around busy roads. Near-road monitoring of air pollution is needed in order to assess the extent and potential health impacts of the resulting exposure. One-third of Canadians live near major roads and are thus potentially exposed to traffic emissions. This report documents a pilot study conducted between 2015 and 2017 involving six monitoring stations in the cities of Vancouver, British Columbia and Toronto, Ontario.This research demonstrated that vehicle emissions can dramatically increase the concentrations of some air pollutants near major roads. Highly polluting diesel trucks are making a disproportionate contribution and they represent the major source of key pollutants such as nitrogen oxides and black carbon. Data for these pollutants indicate that excessive exposure to diesel exhaust can occur near roads with a significant proportion of truck traffic. Canada’s cold winters can increase concentrations. Ultrafine particle concentrations, for example, are higher in winter. Nitrogen oxide concentrations are higher on cold winter days, suggesting that the emission control systems for diesel vehicles may not perform well at low temperatures. Finally, non-tailpipe emissions of particles from brakes and tires have been rising in Toronto since 2012 and now exceed primary emissions through tailpipes.