Measuring public health accountability of air quality management

Accountability of air quality management is often measured by tracking ambient pollution concentrations over time. These changes in ambient air quality are rarely linked to changes in public health, a major driver for such programs. We propose a method to assess the accountability of air quality management programs with respect to improvements in public health by estimating national temporal trends in health risk attributable to air pollution. The air health indicator (AHI) is a function of two temporal functions, annual air pollutant concentrations and annual estimates of health risk obtained by time series statistical methods, to indicate the trend in annual percent attributable risk (the product of concentration and risk times 100). Random effects models are used to obtain a distribution of risk over space. The model is illustrated by examining the association between daily nonaccidental deaths in 24 of Canada's largest cities and daily concentrations of ozone and nitrogen dioxide over the 17-year period 1984-2000. Our analysis demonstrates that examining trends in exposure alone, which has typically been the approach to air quality indicators, provides an incomplete picture of trends in the impact of air pollution. The AHI appears to provide a more informative measure of the population burden of illness associated with air pollution over time.