Background Approximately 2.9 million deaths are attributed to ambient fine particle air pollution around the world each year (PM2.5). In general, cohort studies of mortality and outdoor PM2.5 concentrations have limited information on individuals exposed to low levels of PM2.5 as well as covariates such as smoking behaviours, alcohol consumption, and diet which may confound relationships with mortality. This study provides an updated and extended analysis of the Canadian Community Health Survey-Mortality cohort: a population-based cohort with detailed PM2.5 exposure data and information on a number of important individual-level behavioural risk factors. We also used this rich dataset to provide insight into the shape of the concentration-response curve for mortality at low levels of PM2.5. Methods Respondents to the Canadian Community Health Survey from 2000 to 2012 were linked by postal code history from 1981 to 2016 to high resolution PM2.5 exposure estimates, and mortality incidence to 2016. Cox proportional hazard models were used to estimate the relationship between non-accidental mortality and ambient PM2.5 concentrations (measured as a three-year average with a one-year lag) adjusted for socio-economic, behavioural, and time-varying contextual covariates. Results In total, 50,700 deaths from non-accidental causes occurred in the cohort over the follow-up period. Annual average ambient PM2.5 concentrations were low (i.e. 5.9 μg/m3, s.d. 2.0) and each 10 μg/m3 increase in exposure was associated with an increase in non-accidental mortality (HR = 1.11; 95% CI 1.04–1.18). Adjustment for behavioural covariates did not materially change this relationship. We estimated a supra-linear concentration-response curve extending to concentrations below 2 μg/m3 using a shape constrained health impact function. Mortality risks associated with exposure to PM2.5 were increased for males, those under age 65, and non-immigrants. Hazard ratios for PM2.5 and mortality were attenuated when gaseous pollutants were included in models. Conclusions Outdoor PM2.5 concentrations were associated with non-accidental mortality and adjusting for individual-level behavioural covariates did not materially change this relationship. The concentration-response curve was supra-linear with increased mortality risks extending to low outdoor PM2.5 concentrations.

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Background:Ambient fine particulate air pollution with aerodynamic diameter ≤2.5 μm (PM2.5) is an important contributor to the global burden of disease. Information on the shape of the concentration–response relationship at low concentrations is critical for estimating this burden, setting air quality standards, and in benefits assessments.Objectives:We examined the concentration–response relationship between PM2.5 and nonaccidental mortality in three Canadian Census Health and Environment Cohorts (CanCHECs) based on the 1991, 1996, and 2001 census cycles linked to mobility and mortality data.Methods:Census respondents were linked with death records through 2016, resulting in 8.5 million adults, 150 million years of follow-up, and 1.5 million deaths. Using annual mailing address, we assigned time-varying contextual variables and 3-y moving-average ambient PM2.5 at a 1×1 km spatial resolution from 1988 to 2015. We ran Cox proportional hazards models for PM2.5 adjusted for eight subject-level indicators of socioeconomic status, seven contextual covariates, ozone, nitrogen dioxide, and combined oxidative potential. We used three statistical methods to examine the shape of the concentration–response relationship between PM2.5 and nonaccidental mortality.Results:The mean 3-y annual average estimate of PM2.5 exposure ranged from 6.7 to 8.0 μg/m3 over the three cohorts. We estimated a hazard ratio (HR) of 1.053 [95% confidence interval (CI): 1.041, 1.065] per 10-μg/m3 change in PM2.5 after pooling the three cohort-specific hazard ratios, with some variation between cohorts (1.041 for the 1991 and 1996 cohorts and 1.084 for the 2001 cohort). We observed a supralinear association in all three cohorts. The lower bound of the 95% CIs exceeded unity for all concentrations in the 1991 cohort, for concentrations above 2 μg/m3 in the 1996 cohort, and above 5 μg/m3 in the 2001 cohort.Discussion:In a very large population-based cohort with up to 25 y of follow-up, PM2.5 was associated with nonaccidental mortality at concentrations as low as 5 μg/m3. https://doi.org/10.1289/EHP5204

The World Health Organization (WHO) recently released new guidelines for outdoor fine particulate air pollution (PM 2.5 ) recommending an annual average concentration of 5 μg/m 3 . Yet, our understanding of the concentration-response relationship between outdoor PM 2.5 and mortality in this range of near-background concentrations remains incomplete. To address this uncertainty, we conducted a population-based cohort study of 7.1 million adults in one of the world’s lowest exposure environments. Our findings reveal a supralinear concentration-response relationship between outdoor PM 2.5 and mortality at very low (<5 μg/m 3 ) concentrations. Our updated global concentration-response function incorporating this new information suggests an additional 1.5 million deaths globally attributable to outdoor PM 2.5 annually compared to previous estimates. The global health benefits of meeting the new WHO guideline for outdoor PM 2.5 are greater than previously assumed and indicate a need for continued reductions in outdoor air pollution around the world.

Canadian Cancer Statistics is an annual publication that provides estimates of the burden of cancer in Canada for the current year. About 2 in 5 Canadians will develop cancer in their lifetime, and about 1 in 4 Canadians will die of cancer. In 2015, it is estimated that 196,900 Canadians will develop cancer, and 78,000 will die of cancer. More than half of new cancer cases (51%) will be lung, breast, colorectal and prostate cancer. Lung cancer is the leading cause of cancer death, causing more cancer deaths among Canadians than the other three major cancer types combined. Despite this large impact, there has been a substantial drop in the lung cancer death rate (especially for men) over the past 25 years, which has driven a decline in the overall cancer death rate. Slightly more men than women get cancer in Canada, and the vast majority (89%) of Canadians who develop cancer are over the age of 50. However, cancer can occur at any age. Its impact at a younger age can be particularly devastating. According to Statistics Canada, in 2011, cancer was the leading cause of disease-related death in children under the age of 15 years. Overall, the five-year relative survival ratio for people diagnosed with cancer is 63%, but it ranges widely by the type of cancer. Some cancers have very high five-year relative survival ratios, including thyroid cancer (98%). Other cancers have consistently low five-year relative survival ratios, such as pancreatic cancer (8%).