LATEBREAKER
Environment/Climate Change
Modifying factors and temporal trends of adverse health effects of short-term exposure to PM2.5 in Canada (2001-2018) Hwashin H. Shin* Hwashin Shin Hwashin H. Shin James Owen Anna O. Lukina Muzeyyen Kabasakal Stéphane Buteau
Background: Considerable evidence has been accumulated on acute health outcomes associated with short-term exposure to ambient fine particulate matter (PM2.5). However, spatial and temporal variations (eg, climate changes) and modifying factors of those associations need further analyses.
Methods: PM2.5-related adverse health effects were estimated, covering 80% of Canadians for 18 years (2001-2018). We considered cause, region, season, age, and sex as potential modifying factors of PM2.5-related adverse health effects. Using daily averages of PM2.5 and temperature, and daily counts of hospitalizations and mortality (non-accidental all-cause, circulatory, and respiratory), we estimated city-specific associations, and then national and regional associations. Considering climate changes by time and region, we examined trends in national and regional associations obtained by dynamic models and tested if the trends were linear.
Results: Nationally, PM2.5 exposure was associated with both hospitalizations and mortality with differences by modifying factors. In particular, circulatory mortality and respiratory hospitalization were more attributable to PM2.5 exposure. Eastern Canada was the main source of the significant association with all-cause hospitalization, whereas Western Canada bolstered the association with all-cause mortality. PM2.5 appeared to increase respiratory hospitalization during the warm season, and circulatory hospitalization during the cold season. Circulatory mortality risk was significant for seniors and females.
Conclusions: This study found the adverse health effects of PM2.5 exposures depend on PM2.5 concentrations and other factors (region, cause, season, age, sex). National estimates for the baseline ( ≥1 year, both sexes) cannot be interpreted without consideration of the differences by modifying factors. Seniors and females appeared more vulnerable to short-term exposure to ambient PM2.5, and linear trends in risk varied by the factors.