Abstract View
In-Car Measurements of Traffic-Related Air Pollutants during Car Commuting
CHEOL H. JEONG, Taylor Edwards, Carson Clark, Alison Traub, Dana Umbrio, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 179
Working Group: Indoor Aerosols
Abstract
Traffic-related air pollution (TRAP) has been linked to adverse health outcomes and known to have strong temporal and spatial variabilities. In most urban areas, in-car environments for daily car commuters represent one of the more important contributors to daily TRAP exposure. The exposure to TRAP may induce oxidative stress by stimulating cells to produce excessive reactive oxygen species (ROS). Air pollution exposure in this microenvironments needs to be better characterized to assess any resulting production of ROS and to mitigate in-car exposure to TRAP.
Continuous and integrated measurements of TRAP were carried out inside an electric vehicle during morning and evening rush hours on weekdays in summer, fall, winter, and spring in 2019-2020. The In-Car AiR pollution Exposure study (I-CARE) was conducted over 140 commutes between suburbs and downtown Toronto with both highway and local road routes composed of heavy-traffic roads and quiet residential streets. The in-car measurements of gas and particle-phase air pollutants on roadways included nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), particulate matter (PM2.5), ultrafine particles (UFP), black carbon (BC), and traffic-related trace metals. In this study, continuous concentrations of these gases and PM2.5 were measured by a portable sensor array (AirSENCE), while real-time UFP and BC were measured by a DiSCmini (Matter Aerosol) and MicroAeth (AE51, AethLabs), respectively. In-car trace metals were determined by analyzing integrated filter samples. In addition to the in-car sampling, outside concentrations of UFP and BC were determined simultaneously while driving. All routes and vehicle speeds were recorded by a GPS receiver and a dashcam.
The in-vehicle exposure to TRAP was assessed under various ventilation modes (open vs. closed), road types, cabin filters, and seasons. In order to estimate the production of ROS of in-car PM2.5, filters extracts were analyzed for oxidative potential (OP), the ability of PM2.5 to deplete antioxidants such as ascorbic acid and glutathione. In-car exposure to TRAP in the open mode was approximately double the ambient level in the downtown area. Substantial exposure reduction was achieved in the closed mode. It was found that OP in the open mode was approximately 8 times higher than that in the closed mode. However, excessive CO2 accumulation was observed in the closed mode. Various seasonal mitigation strategies by locations and time intervals were explored to reduce in-car TRAP exposure without the issue of excessive CO2 accumulation.