Variability in ambient ozone and fine particle concentrations and population susceptibility among Canadian health regions.

OBJECTIVES: To estimate the proportion of the Canadian population that is more susceptible to adverse effects of ozone (O3) and fine particle (PM2.5) air pollution exposure and how this varies by health region alongside ambient concentrations of O3 and PM2.5. METHODS: Using data from the census, the Canadian Community Health Survey, vital statistics and published literature, we generated cross-sectional estimates for 2014 of the proportions of the Canadian population considered more susceptible due to age, chronic disease, pregnancy, outdoor work, socio-economic status, and diet. We also estimated 2010-2012 average concentrations of O3 and PM2.5. Analyses were conducted nationally and for 110 health regions. RESULTS: Restrictive criteria (age < 10 or ≥ 75; asthma, chronic obstructive pulmonary disease, heart disease, or diabetes; pregnancy) suggested that approximately one third of the Canadian population is more susceptible, while inclusive criteria (restrictive plus age 10-19 and 65-74, outdoor work, less than high school education, low vitamin C intake) increased this proportion to approximately two thirds. Across health regions, estimates ranged from 24.4% to 41.2% (restrictive) and 61.2% to 87.0% (inclusive). Ten health regions were in the highest quartile of both population susceptibility and O3 or PM2.5 concentrations, all of which were outside major urban centres. CONCLUSIONS: A substantial proportion of the Canadian population exhibits at least one risk factor that increases their susceptibility to adverse effects of O3 and PM2.5 exposure. Both risk communication and management interventions need to be increasingly targeted to regions outside large urban centres in the highest quartiles of both susceptibility and exposure.

Estimated public health impacts of changes in concentrations of fine particle air pollution in Canada, 2000 to 2011.

OBJECTIVES: To estimate the public health impacts of changes in fine particle air pollution in Canada between 2000 and 2011, employing nationally comprehensive exposure estimates and quantifying the impacts on life expectancy, mortality and morbidity. METHODS: We employed spatially comprehensive exposure estimates derived from satellite remote sensing to estimate the effects of actual observed changes in concentrations of fine particulate matter (PM), of median aerodynamic diameter <2.5 µm (i.e., PM2.5), from 2000 to 2011. We estimated changes in life expectancy using standard life table methods and changes in frequency of health outcomes as the product of population, baseline rate of the health outcome and the proportional change in health outcome per specified change in PM2.5 concentration. RESULTS: A population weighted average decrease in PM2.5 of nearly 25% (2.0 µg/m³) was observed between 2000 and 2011. This was estimated to result in a national population weighted average increase in life expectancy of 0.10 years (95% confidence interval 0.03-0.23; up to 0.34 years in specific census divisions) and reductions in the frequency of mortality and morbidity of up to 3.6%. Increases in PM2.5 up to 3.5 µg/m³ were observed in some census divisions, particularly in the prairies. CONCLUSION: At the national level, changes in PM2.5 concentrations between 2000 and 2011 were associated with an estimated improvement in national population weighted average life expectancy and a net reduction in mortality and morbidity. Areas that failed to improve or that worsened during this period warrant additional scrutiny to identify options for reducing PM2.5 concentrations.