10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Spatial and Seasonal Patterns in the Oxidative Burden of Ambient Particulate Matter in Urban Centres
ALISON TRAUB, Cheol H. Jeong, Cuilian Fang, Maryam Shekarrizfard, Ryan Kulka, Hongyu You, Marianne Hatzopoulou, Scott Weichenthal, Greg J. Evans, SOCAAR, University of Toronto
Abstract Number: 962 Working Group: Aerosols and Health - Connecting the Dots
Abstract Exposure to fine airborne particulate matter (PM) is associated with a broad suite of adverse health effects, including cardio-respiratory, neurological, and even metabolic disease (e.g., Alderete et al., 2017; Lim et al., 2012; Oudin et al., 2016). Although there is much uncertainty as to the mechanism of disease evolution following exposure to PM, a likely mechanism is cell and tissue damage as a result of oxidative stress and inflammation (Donaldson and Tran 2002; Li et al. 2003).
In light of this likely mechanism, oxidative potential (OP) – the ability of PM to cause oxidative stress, measured per unit mass of PM – and oxidative burden (OB) – the ability of PM to cause oxidative stress, measured per unit volume of air – have emerged as promising, biologically relevant metrics for assessing risk associated with atmospheric PM (Ayres et al. 2008). Unlike PM mass, these metrics are associated with both cellular inflammatory response, cause-specific mortality, and other adverse health effects (e.g., Harrison and Yin, 2000; Weichenthal et al., 2016).
Assessment of PM OB at high spatial resolution in urban centres could facilitate population-level epidemiological studies. These studies could help inform public policy by providing location-specific information about which PM components contribute most to toxicity in these densely populated areas. To achieve this goal, there is a need for data on ambient PM OB that has high spatial resolution, isolates temporal and spatial variability, and accounts for the effects of oxidation by all redox-active PM components.
This study examined the OB of ambient PM collected simultaneously from 80 sites across the city of Toronto, Canada’s largest city with a population in exceedance of 5 million. To our knowledge, this study will have the highest spatial density of any PM OB study by at least an order of magnitude. Further, simultaneous sample collection for two-week periods in Summer 2016 and then Winter 2016-17, allows us to examine spatial and temporal variability separately.
A further goal of this study is to compare OB results using three different measurement techniques. Specifically, PM OB is being assessed using three common in vitro methods: the ascorbate (AA) assay, the glutathione (GSH) assay, and the dithiothreitol (DTT) assay. Previous studies have identified that these three assays are sensitive to different components of ambient PM (e.g., Calas et al. 2017; Fang et al. 2016; Weichenthal et al. 2016). Therefore, the combined use of these three common assays will provide a more comprehensive picture of PM OB and will help to elucidate the relationship between OB measurements made using these assays. Although analysis for Toronto samples is still underway, patterns suggest that the OB measured with the GSH assay exhibits both the greatest spatial variability and the strongest seasonal dependence, followed by the OB measured by the DTT and AA assays.