HEALTH IMPACT OF AMBIENT PARTICULATE AIR POLLUTION IN ITALY

Abstract

Background The scientific evidence on the health effects of ambient air pollution is substantial. Although several questions remain unanswered, several epidemiological studies have demonstrated the adverse effects of air pollution and characterised dose-response relationships between mortality and pollutants. Among these, the role of particulate matter (PM) has been investigated with regards to its long-term effects on mortality. Due to the ubiquitous nature of PM air pollution, it is likely that its overall impact on human health is large, even if risks are relatively small compared to other environmental risk factors. Large numbers of deaths in urban areas attributable to PM have been estimated in many health impact studies that have been influential in policy making. To further strengthen the case for reduction of PM concentrations, methods that estimate also the impact in terms of life expectancy might be useful. Methods Italian population and all-causes mortality data for 1998 have been used. A life table approach has been followed to calculate the years of life lost (YLL) due to PM pollution, using consevative dose-response risk coefficients (RR = 1.026 per μ10 μg/m3 PM10 increase) estimated in published studies. Linearity of dose-response function is assumed and proportional increases in RR are not age-dependent. Total number of YLL as a function of PM10 levels has been calculated assuming constant rates over time, constant number of births in years after 1998 and null net migration effect. Various scenarios of possible reductions in ambient PM10 concentration have been simulated, starting from a reduction of 5 μg/m3 up to 40 μg/m3. Effects for delays of 5, 10, 20 and 30 years have been calculated, with 95% uncertainty intervals. Results A reduction of 10 μg/m3 in PM10 concentration, with immediate effects, would results in a gain in life expectancy for men of 0.21 years, i.e. about two and a half months (0.17 for women). For all the reduction factors the effect is always higher for men. The total gain for the Italian population is 5.88 millions of life years for men and 5.15 for women. Assuming delays between PM reduction and occurrence of effects, the gains decrease. Gains for larger concentrations reductions are in proportion. Comment In Italy, as in other industrialised countries, reduction of PM concentrations would produce substantial improvement in mortality and life expectancy. Limitations in the methodology and the need to make strong assumptions should be considered-for example uncertainty around the estimates may be larger than reflected by available uncertainty intervals. However health impact assessment type studies have proven informative and effective as a means of communication with the general public and policy makers alike.