The urban multi-pollutant mixture measured in the Study of Winter Air Pollution in Toronto (SWAPIT)

Air quality concerns persist in urban areas due to the density of pollutant releases and population. This leads to complexities in understanding air pollution impacts given the high spatiotemporal variability of ambient pollutant levels. Those complexities are exacerbated by the lack of integration among the research and management activities associated with the air quality issues of smog, acid deposition, trace contaminants, and air toxics. The Study of Winter Air Pollution in Toronto (SWAPIT) involves over 100 scientific and technical collaborators from government and academia working to characterize the composition and spatiotemporal variability of the whole urban air pollution mixture and to better understand urban air pollution sources and impacts. A six-week field campaign was carried out from January to March 2024 using a variety of measurement techniques at multiple locations in the Toronto area. Campaign timing allowed for a focus on the relatively understudied winter period when low temperature and light alter secondary pollutant formation, and seasonal pollutant sources such as roadway de-icing and residential wood combustion are active. Results will be presented to demonstrate the differences in spatial patterns between pollutants, the ongoing impacts of urban transportation sources, and the growing role of non-exhaust pollutants. Insights into human and wildlife health will also be presented along with improvements to satellite and chemical transport modelling tools that have been driven by measurements taken during the SWAPIT field campaign.