Environment/Climate Change
Long-term exposure to outdoor ultrafine particles and black carbon and mortality from neurodegenerative outcomes in Canada’s two largest cities. Emmanuelle Batisse* Emmanuelle Batisse Marshall LLoyd Christel Renoux Arman Ganji Junshi Xu Marianne Hatzopoulou Jill Baumgartner Scott Weichenthal
Background: In urban areas, transportation and industrial activities emit large quantities of air pollutants such as ultrafine particles (UFP, <0.1 um) and black carbon (BC). Due to their smaller size, UFP can reach vital organs including the central nervous system. Emerging evidence suggests that long-term exposures to UFP may increase the risk of mortality from neurodegenerative diseases, but studies are limited and none accounted for UFP size.
Aim: We evaluated associations between long-term exposures to outdoor UFP and BC and mortality from neurodegenerative outcomes among members of the Canadian Census Health and Environment Cohorts living in Montreal and Toronto.
Methods: We followed 2.1 million adults between 2001 and 2019. Information on vital status and cause of death were from the Canadian Vital Statistics Database and high-resolution exposure data for UFP number concentrations, UFP size, and BC mass concentrations were assigned to residential locations using three-year moving averages. We used Cox proportional hazards models to estimate associations between outdoor UFP/BC and mortality from dementia, Parkinson’s disease and amyotrophic lateral sclerosis (ALS), adjusting for sociodemographic confounders and co-pollutants. In future analyses, we will use inverse-probability weighting to estimate the controlled direct effect of UFP/BC under the hypothetical scenario where competing events are eliminated.
Preliminary results: We included over 19 million person-years and 20,000 deaths. UFP were associated with increased neurodegenerative mortality (HR, 95% CI per 10,000 particles/cm³ UFP: 1.112, 1.074–1.152; per 500 ng/m³ BC: 0.993, 0.977–1.008). Further, UFP were linked to dementia mortality (1.149, 1.107-1.192), while BC was associated with mortality from Parkinson’s disease (1.051, 1.002-1.103) and ALS (1.028, 0.947-1.116). Our findings suggest that UFP and BC could be modifiable risk factors to target in efforts to reduce neurodegenerative mortality.
