Elucidating Spatial Variations of Non-Tailpipe Emissions through Comprehensive Saturation and Mobile Measurements across Two Seasons
CHEOL H. JEONG, Yee Ka Wong, Nicole Trieu, Sophie Roussy, Maria-Teresa Pay-Perez, Xing Wang, Taylor Edwards, Junshi Xu, Milad Saeedi, Arman Ganji, Bruce Urch, Marianne Hatzopoulou, Arthur W. H. Chan, Scott Weichenthal, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 63
Working Group: Urban Aerosols
Abstract
Saturation and mobile measurements were employed to explore the spatial variation of tailpipe and non-tailpipe emissions, including resuspended road dust and brake wear particulate matter (PM), across Toronto, Canada. Saturation sampling involved over 80 portable filter samplers deployed at 30~40 sites to collect weekly PM2.5 and PM10 filter-samples across two seasons (October – November 2023, January - March 2024) to determine PM mass, trace elements, and oxidative potential. Ogawa badge sampling was also employed to measure nitrogen oxides (NOx) as an indicator of tailpipe emissions. Mobile sampling over 3500 km and 180 driving hours covered busy urban centres to background parks across the city, focusing on resuspended PM on roadways, as well as ultrafine particles (UFP) and black carbon (BC). To evaluate daily baseline changes and the performance of portable devices in the mobile vehicle, routine stationary sampling at designated sites was included.
An excellent correlation between some trace elements and total PM was observed across the saturation sites. Strong spatial variations in trace elements were noted, particularly with elements such as barium and copper, which are indicative of brake wear. These elements contributed more to PM at sites situated along major roadways. Highly localized increases in resuspended PM were influenced by nearby construction activities, whereas mostly higher UFP and BC, reflective of tailpipe emissions, were found along major roadways. The distinct impacts of brake wear and road dust demonstrated the influence of road types and nearby activities on non-tailpipe emissions. The study underscores the growing contribution of trace metals to PM mass in roadside environments and highlights the importance of understanding the spatial differences in non-tailpipe emissions. Further investigations through the seasonal field campaigns will provide deeper insights into these patterns and help develop strategies for monitoring and mitigating urban non-tailpipe emissions.