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

Abstract

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.

Short‐Term Exposure to Fine Particulate Matter Air Pollution Is Preferentially Associated With the Risk of ST‐Segment Elevation Acute Coronary Events

“…Odds ratios using both the standard linear and threshold models were estimated for all ACS, STEMI, NSTEMI, UA, and NSTE‐ACS events for all patients and for patients with and without CAD. For comparison purposes, and consistent with reporting from various studies and reviews of the literature,1, 2, 3, 4, 5, 6, 7, 8, 11, 14, 15, 16 odds ratios associated with 10‐μg/m 3 incremental increases in PM 2.5 concentration are presented.…”

“…Various prospective cohort studies of long‐term exposure (years or decades) have found that elevated PM 2.5 exposures are associated with increased risk of cardiovascular disease mortality3, 4, 5, 6, 7, 8, 9 and may contribute to the initiation and progression of related chronic diseases including atherosclerosis, hypertension, and diabetes 10, 11. The Global Burden of Disease 2010 analysis reported comparative burden of disease risk assessments from 67 risk factors.…”

Cross-track Infrared Sounder (CrIS) satellite observations of tropospheric ammonia

“…Seinfeld and Pandis, 1988). These particles form smog and, in addition to being statistically associated with health impacts, such as bronchitis, asthma, cardiovascular disease and lung disease, cause premature deaths (Schwartz et al, 2002;Reiss et al, 2007;Pope et al, 2002Pope et al, , 2009Crouse et al, 2012). For example, there is a 6 and 8 % increase in the risk of cardiopulmonary and lung cancer mortality associated with exposure to 10 µg m −3 increases in PM 2.5 concentrations (Pope et al, 2002).…”

Air pollution and life expectancy in China and beyond

“…These two prospective cohort studies have undergone extensive reanalysis, replication, and extended analysis (5-7). Additional cohort studies have also been reported, and when evaluated in a meta-analytic review framework there is significant evidence that fine PM exposure contributes to risk of mortality (8)(9)(10).…”