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., PM_2.5), 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 PM_2.5 concentration. RESULTS: A population weighted average decrease in PM_2.5 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 PM_2.5 up to 3.5 µg/m³ were observed in some census divisions, particularly in the prairies. CONCLUSION: At the national level, changes in PM_2.5 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 PM_2.5 concentrations.