posted on 2021-07-09, 19:33authored byJun-Wei Xu, Randall V. Martin, Greg J. Evans, Dana Umbrio, Alison Traub, Jun Meng, Aaron van Donkelaar, Hongyu You, Ryan Kulka, Richard T. Burnett, Krystal J. Godri Pollitt, Scott Weichenthal
Fine particulate air pollution (PM2.5) is a leading
contributor to the overall global burden of disease. Traditionally,
outdoor PM2.5 has been characterized using mass concentrations
which treat all particles as equally harmful. Oxidative potential
(OP) (per μg) and oxidative burden (OB) (per m3)
are complementary metrics that estimate the ability of PM2.5 to cause oxidative stress, which is an important mechanism in air
pollution health effects. Here, we provide the first national estimates
of spatial variations in multiple measures (glutathione, ascorbate,
and dithiothreitol depletion) of annual median outdoor PM2.5 OB across Canada. To do this, we combined a large database of ground-level
OB measurements collected monthly prospectively across Canada for
2 years (2016–2018) with PM2.5 components estimated
using a chemical transport model (GEOS-Chem) and satellite aerosol
observations. Our predicted ground-level OB values of all three methods
were consistent with ground-level observations (cross-validation R2 = 0.63–0.74). We found that forested
regions and urban areas had the highest OB, predicted primarily by
black carbon and organic carbon from wildfires and transportation
sources. Importantly, the dominant components associated with OB were
different than those contributing to PM2.5 mass concentrations
(secondary inorganic aerosol); thus, OB metrics may better indicate
harmful components and sources on health than the bulk PM2.5 mass, reinforcing that OB estimates can complement the existing
PM2.5 data in future national-level epidemiological studies.