Risk of Nonaccidental and Cardiovascular Mortality in Relation to Long-term Exposure to Low Concentrations of Fine Particulate Matter: A Canadian National-Level Cohort Study

• Published in: Environmental health perspectives Vol. 120; no. 5; pp. 708 - 714
• Main Authors: Crouse, Dan L., Peters, Paul A., van Donkelaar, Aaron, Goldberg, Mark S., Villeneuve, Paul J., Brion, Orly, Khan, Saeeda, Atari, Dominic Odwa, Jerrett, Michael, Pope, C. Arden, Brauer, Michael, Brook, Jeffrey R., Martin, Randall V., Stieb, David, Burnett, Richard T.
• Format: Journal Article
• Language: English
• Published: Research Triangle Park, NC National Institute of Environmental Health Sciences 01.05.2012; US Department of Health and Human Services
• Subjects: Adult; Adults; Aged; Air; Air Pollutants - toxicity; Air pollution; Biological and medical sciences; Canada; Canada - epidemiology; Cardiovascular diseases; Cardiovascular Diseases - mortality; Cohort Studies; Death; Disease models; Ecological modeling; Environment. Living conditions; Environmental aspects; Environmental pollutants toxicology; Estimates; Exposure; Female; Health aspects; Heart diseases; Humans; International Statistical Classification of Diseases; Male; Mathematical models; Medical sciences; Middle Aged; Mortality; Mortality risk; Myocardial ischemia; Particle Size; Particles; Particulate matter; Public health. Hygiene; Public health. Hygiene-occupational medicine; Risk; Risk Factors; Socioeconomic Factors; Spatial models; Survival; Toxicology; Canada; North America; America; fine particulate matter; Low dose; Mortality; cardiovascular mortality; Risk; Exposure; Epidemiology; Long term; Canada; Health and environment; Fine particle; Cohort study; Risk factor; Air pollution; Circulatory system; Public health
• ISSN: 0091-6765; 1552-9924; 1552-9924
• DOI: 10.1289/ehp.1104049

Background: Few cohort studies have evaluated the risk of mortality associated with long-term exposure to fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM₂.₅)]. This is the first national-level cohort study to investigate these risks in Canada. Objective: We investigated the association between long-term exposure to ambient PM₂.₅ and cardiovascular mortality in nonimmigrant Canadian adults. Methods: We assigned estimates of exposure to ambient PM₂.₅ derived from satellite observations to a cohort of 2.1 million Canadian adults who in 1991 were among the 20% of the population mandated to provide detailed census data. We identified deaths occurring between 1991 and 2001 through record linkage. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for available individual-level and contextual covariates using both standard Cox proportional survival models and nested, spatial random-effects survival models. Results: Using standard Cox models, we calculated HRs of 1.15 (95% CI: 1.13, 1.16) from nonaccidental causes and 1.31 (95% CI: 1.27, 1.35) from ischemic heart disease for each 10-μg/m³ increase in concentrations of PM₂.₅. Using spatial random-effects models controlling for the same variables, we calculated HRs of 1.10 (95% CI: 1.05, 1.15) and 1.30 (95% CI: 1.18, 1.43), respectively.We found similar associations between nonaccidental mortality and PM₂.₅ based on satellite-derived estimates and ground-based measurements in a subanalysis of subjects in 11 cities. Conclusions: In this large national cohort of nonimmigrant Canadians, mortality was associated with long-term exposure to PM₂.₅. Associations were observed with exposures to PM₂.₅ at concentrations that were predominantly lower (mean, 8.7 μg/m³; interquartile range, 6.2 μg/m³) than those reported previously.