Personal exposures to traffic-related air pollution in three Canadian bus transit systems: the Urban Transportation Exposure Study

Keith Van Ryswyk,Scott Weichenthal,Liu Sun,Angelos T Anastasopolos,Kelly Sabaliauskas,Lance Wallace,Ryan Kulka,Mathieu Rouleau,Greg J Evans

doi:10.1038/s41370-020-0242-2

Abstract

BackgroundExposure to traffic-related air pollution (TRAP) is associated with increased incidence of several cardiopulmonary diseases. The elevated TRAP exposures of commuting environments can result in significant contributions to daily exposures.ObjectivesTo assess the personal TRAP exposures (UFPs, BC, PM2.5, and PM10) of the bus transit systems of Toronto, Ottawa, and Vancouver, Canada. Personal exposure models estimated the contribution of bus commuting to daily TRAP exposures. Associations between bus type and riding exposures and bus stop/station type and waiting exposures were estimated.ResultsBus commuting (4.6% of the day) contributed ~59%(SD = 15%), 60%(SD = 20%), and 57%(SD = 18%) of daily PM2.5-Ba and 70%(SD = 19%), 64%(SD = 15%), and 70%(SD = 15%) of daily PM2.5-Fe, in Toronto, Ottawa, and Vancouver, respectively. Enclosed bus stations were found to be hotspots of PM2.5 and BC. Buses with diesel particulate filters (DPFs) and hybrid diesel/electric propulsion were found to have significantly lower in-bus PM2.5, UFP, and BC relative to 1983–2003 diesel buses in each city with the exception of UFP in Vancouver.SignificancePersonal exposures for traffic-related air pollutants were assessed for three Canadian bus transit systems. In each system, bus commuting was estimated to contribute significantly toward daily exposures of fine-fraction Ba and Fe as well as BC. Exposures while riding were associated with bus type for several pollutants in each city. These associations suggest the use of hybrid diesel/electric buses equipped with diesel particulate filters have improved air quality for riders.

Highlights

IntroductionTraffic-related air pollution (TRAP) is ubiquitous in urban environments and constitutes a significant burden on public health
Supplementary information The online version of this article contains supplementary material, which is available to authorized users.Health, McGill University, Montreal, QC H3A 1A2, CanadaTraffic-related air pollution (TRAP) is ubiquitous in urban environments and constitutes a significant burden on public health
Contribution of bus commuting to daily exposure of PM2.5 mass, its elemental constituents, black carbon (BC), and ultrafine particles (UFPs)

Summary

Introduction

Traffic-related air pollution (TRAP) is ubiquitous in urban environments and constitutes a significant burden on public health. In North America, the transportation sector is estimated to account for 32% of total fine particulate matter (PM2.5) mortality [12]. This evidence has led to the adoption of increasingly stringent regulations resulting in reductions of engine and vehicle emissions and regulated air pollutants [13]. Exposure to traffic-related air pollution (TRAP) is associated with increased incidence of several cardiopulmonary diseases. The elevated TRAP exposures of commuting environments can result in significant contributions to daily exposures

Objectives

Methods

Results

Discussion

Conclusion