Predicting Spatial Variations in Multiple Measures of PM 2.5 Oxidative Potential and Magnetite Nanoparticles in Toronto and Montreal, Canada.

There is growing interest to move beyond fine particle mass concentrations (PM 2.5 ) when evaluating the population health impacts of outdoor air pollution. However, few exposure models are currently available to support such analyses. In this study, we conducted large-scale monitoring campaigns across Montreal and Toronto, Canada during summer 2018 and winter 2019 and developed models to predict spatial variations in (1) the ability of PM 2.5 to generate reactive oxygen species in the lung fluid (ROS), (2) PM 2.5 oxidative potential based on the depletion of ascorbate (OP AA ) and glutathione (OP GSH ) in a cell-free assay, and (3) anhysteretic magnetic remanence ( X ARM ) as an indicator of magnetite nanoparticles. We also examined how exposure to PM oxidative capacity metrics (ROS/OP) varied by socioeconomic status within each city. In Montreal, areas with higher material deprivation, indicating lower area-level average household income and employment, were exposed to PM 2.5 characterized by higher ROS and OP. This relationship was not observed in Toronto. The developed models will be used in epidemiologic studies to assess the health effects of exposure to PM 2.5 and iron-rich magnetic nanoparticles in Toronto and Montreal.