Comparing estimated risks for air pollution with risks for other health effects.

It is now widely accepted that air pollution has important effects on mortality, over timescales at least long enough to impact on annual mortality rates. Given estimates of the size of these effects, it is possible to predict changes to mortality rates that might accrue following proposed reductions in pollution concentrations.Changes in mortality rates imply changes in survival distributions, and these can be estimated using standard life-table calculations. When estimating for a whole population, it is necessary to separate the dimensions of age and calendar year, and we have developed a system of spreadsheets, IOMLIFET, to carry out and summarise the detailed calculations required. The system permits great flexibility in input assumptions and output summaries, including monetary values with or without discounting. It can be applied to changes in mortality from any cause, not only air pollution.It is often helpful to compare the impacts of different kinds of health effects. This report investigates aspects of comparability of effects in individual birth cohorts and in mixed-age populations, based on cause-specific mortality rates for England and Wales. The predicted effects of a 10 �g.m-3 reduction in airborne PM2.5 air pollution (broadly equivalent to removing all anthropogenic particles) from US cohort studies are compared with the effects of eliminating the mortality risks of passive smoking and of motor vehicle traffic accidents (MVTA).For a single birth cohort, the impacts of eliminating passive smoking or MVTA are roughly similar in males, around 12 weeks’ additional expectation of life. In females, they yield 2 months and one month respectively. In both sexes, a 10 �g.m-3 reduction in airborne PM2.5 air pollution is predicted to gain some seven months’ expectation of life. While these estimates are subject to uncertainty, they show that the effect of ambient air pollution on mortality is a public health issue of substantial importance. We expect similar results would be obtainable in other countries. “”