Impact of legislative changes to reduce the sulphur content in fuels in Europe on daily mortality in 20 European cities: an analysis of data from the Aphekom project

Following the implementation of three successive European Directives during the 1990s to reduce the sulphur content of fuels, background SO2 concentrations in European cities have fallen substantially. We investigated the magnitude of the short-term associations between daily SO2 concentrations and mortality during the various phases of legislation. Daily counts of all-cause and cause-specific mortality, SO2 concentration, temperature and humidity were obtained for 20 European cities participating in the Aphekom project during 1990–2008. Poisson regression was used to estimate the city-specific risks of death associated with changes in SO2 concentrations for the time periods before legislation and subsequent periods following the implementation of the three European Directives. City-specific risk estimates were pooled using meta-regression. We also estimated the health impact associated with changes in SO2 concentrations during these pre-and post-implementation periods. During the study period, 10 μg/m3 increases in SO2 levels were associated with increases in all-cause (0.53 %), respiratory (0.49 %) and cardiovascular (0.72 %) mortality. We found no evidence of changes in the SO2 concentration–response function across the implementation periods. We estimated, annually, a total of 639, 1,093 and 1,616 premature deaths across the 14 EU cities as result of respective reductions in SO2 concentrations in each of the three implementation periods. Our study suggests that the linear relationship between daily SO2 concentrations and mortality has remained unaltered despite substantial reductions in ambient concentrations in recent years arising from EU directives to limit sulphur content in fuel. This linearity suggests that new legislation to reduce SO2 concentrations further will bring about additional public health benefits.