AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Characterization of Winter Air Pollutant Gradients near a Major Highway
CHEOL H. JEONG, Nathan Hilker, Jon M. Wang, Jerzy Debosz, Robert Healy, Uwayemi Sofowote, Tony Munoz, Dennis Herod, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 533 Working Group: Urban Aerosols
Abstract In Toronto, the largest city in Canada, approximately 13%, 24%, and 56% of the total population lives within 50 m, 100 m, and 250 m of major roadways, respectively. Living and spending significant time near major roadways has been identified as a risk factor for a number of adverse health outcomes. Previous studies have reported that elevated concentrations of traffic-related pollutants such as ultrafine particles (UFP), black carbon (BC), and nitrogen oxides (NOx) generally occur within 50 m from roadways, while background levels are reached within 150-500 m. However, the spatial variability of air pollutants near roadways (< 250 m) can be affected both by distance to roadways and meteorological variables. Thus, influences of microscale meteorology, especially in winter, on the decay gradients of traffic-related and regional scale pollutants near major roadways should be characterized in order to estimate the extent to which populations are exposed to elevated pollution levels. Knowledge of decay gradients in winter is also required to better understand seasonal relationships between pollution exposure and health effects.
In this study, primary traffic-related pollutants (UFP, BC, NOx) and PM2.5 components (metals, organic aerosol, sulphate, nitrate, ammonium) were simultaneously and continuously measured at 10 m and 150 m distances from a major Canadian highway over 3 weeks, along with meteorological parameters and traffic counts. A wide range of ambient temperatures, -11°C to +18°C was observed during this winter intensive campaign. The spatial variabilities of traffic-related pollutants were characterized by wind profiles (downwind vs. upwind, stagnant air) and ambient temperature. In addition to the short intensive campaign, longer-term measurements of UFP, NOx, and BC in winter months at the near-highway station will be discussed to elucidate the influence of ambient temperature on real-world emission factors.