Associations between long-term PM2.5 and ozone exposure and mortality in the Canadian Census Health and Environment Cohort (CANCHEC), by spatial synoptic classification zone
- DOI
- Language of the publication
- English
- Date
- 2017-12-20
- Type
- Article
- Author(s)
- Cakmak, Sabit
- Hebbern, Chris
- Pinault, Lauren
- Lavigne, Eric
- Vanos, Jennifer
- Crouse, Dan Lawson
- Tjepkema, Michael
- Publisher
- Elsevier
Abstract
Studies suggest that long-term chronic exposure to fine particulate matter air pollution can increase lung cancer mortality. We analyzed the association between long term PM2.5 and ozone exposure and mortality due to lung cancer, ischemic heart disease, and chronic obstructive pulmonary disease, accounting for geographic location, socioeconomic status, and residential mobility. Subjects in the 1991 Canadian Census Health and Environment Cohort (CanCHEC) were followed for 20 years, and assigned to regions across Canada based on spatial synoptic classification weather types. Hazard ratios (HR) for mortality, were related to PM2.5 and ozone using Cox proportional hazards survival models, adjusting for socioeconomic characteristics and individual confounders. An increase of 10 μg/m3 in long term PM2.5 exposure resulted in an HR for lung cancer mortality of 1.26 (95% CI 1.04, 1.53); the inclusion in the model of SSC zone as a stratum increased the risk estimate to HR 1.29 (95% CI 1.06, 1.57). After adjusting for ozone, HRs increased to 1.49 (95% CI 1.23, 1.88), and HR 1.54 (95% CI 1.27, 1.87), with and without zone as a model stratum. HRs for ischemic heart disease fell from 1.25 (95% CI 1.21, 1.29) for exposure to PM2.5, to 1.13 (95% CI 1.08, 1.19) when PM2.5 was adjusted for ozone. For COPD, the 95% confidence limits included 1.0 when climate zone was included in the model. HRs for all causes of death showed spatial differences when compared to zone 3, the most populated climate zone. Exposure to PM2.5 was related to an increased risk of mortality from lung cancer, and both ozone and PM2.5 exposure were related to risk of mortality from ischemic heart disease, and the risk varied spatially by climate zone.
Plain language summary
Under the Federal Clean Air Regulatory Agenda (CARA), Health Canada conducts scientific research to evaluate the health risks of environmental pollutants, such as particulate matter (PM2.5) and ozone. Elevated exposure to ambient outdoor air pollution has been shown to contribute to acute and chronic health effects in the Canadian population. Increasing evidence is available for an association between long term air pollution exposure and lung cancer, ischemic heart disease (IHD), and chronic obstructive pulmonary disease (COPD) mortality, although uncertainties remain around the strength of the causal link, due to difficulties accounting for the effect of smoking, changes in exposure over time, differences in the ambient pollution mix in different areas, and the long time period required for development of lung cancer or IHD , and COPD. In this study, Health Canada in collaboration with Statistics Canada and the University of New Brunswick looked at the relationship between long-term exposure to ambient PM2.5 and ozone and their association with lung cancer, IHD and COPD mortality in the Canadian Census Health and Environment Cohort (CanCHEC) and to see if these effects differ by climate zones. Participants with 20 years of follow-up in CanCHEC were assigned to one of seven climate zones across Canada based on spatial synoptic classification (SSC) weather types. Hazard ratios (HRs) for mortality related to PM2.5 and ozone were calculated and the results suggest that long term exposure to ambient PM2.5 was significantly related to an increased risk of mortality from lung cancer, and both ozone and PM2.5 exposure were related to risk of mortality from ischemic heart disease, and the risk varied spatially by climate zone. The results from this study will further enhance our understanding of human health risk associated with exposure to ambient air pollution and may also be used in the development of Canadian Ambient Air Quality Standards.
Subject
- Health,
- Health and safety