AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Size-Resolved Ultrafine Particle Concentrations near Busy Roadways: A Decade of Diameter Data
NATHAN HILKER, Cheol H. Jeong, Jon M. Wang, Kelly Sabaliauskas, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 642 Working Group: Urban Aerosols
Abstract In large metropolitan areas such as Toronto, Canada, sizable portions of residents live within close proximities to major roadways. Exposure to high levels of traffic-related air pollution is a risk factor for a wide array of adverse health outcomes. One subset of these air contaminants, ultrafine particles (UFPs; particles with diameters less than 100nm), has garnered significant attention in recent years. While UFP concentrations in cities are often strongly related to traffic, the association is complex. Total UFP concentrations near roadways varies diurnally due to differences in traffic and meteorological conditions, as well as by season as temperature plays a critical role in nucleation and gas-to-particle partitioning dynamics. Separation of these shorter-term sources of variability allows resolution of long-term patterns reflective of the slowly evolving vehicle fleet in Toronto, as well as more stringent emission standards for the release of sulphur dioxide (SO2) from major industrial facilities.
In this study, UFP measurements were taken using two collocated instruments: a Scanning Mobility Particle Sizer (SMPS; TSI 3080), and a Fast Mobility Particle Sizer (FMPS; TSI 3091), at the Southern Ontario Centre for Atmospheric Aerosol Research (SOCAAR) in Toronto, Canada between 2006 and 2016. The objectives of this study were to 1) examine the long-term trends in UFP concentrations over the last decade, 2) infer the underlying causes of these changes in UFP concentrations, and 3) examine seasonal and diurnal variability. Using time series analysis and signal processing, the relationship between UFP, traffic volume, and meteorological parameters were examined. These long-term trends were compared with other commonly measured air pollutants (nitrogen oxides, NOx; carbon monoxide, CO; black carbon, BC; SO2; and particulate matter less than 2.5 microns in diameter, PM2.5), thereby showing the co-benefits of improved traffic emissions and control technologies over time.