Which specific causes of death are associated with short term exposure to fine and coarse particles in Southern Europe? Results from the MED-PARTICLES project.

We investigated the short-term effects of particles with aerodynamic diameter less than 2.5μm (PM2.5), between 2.5 and 10μm (PM2.5-10) and less than 10μm (PM10) on deaths from diabetes, cardiac and cerebrovascular causes, lower respiratory tract infections (LRTI) and chronic obstructive pulmonary disease (COPD) in 10 European Mediterranean metropolitan areas participating in the MED-PARTICLES project during 2001-2010. In the first stage of the analysis, data from each city were analyzed separately using Poisson regression models, whereas in the second stage, the city-specific air pollution estimates were combined to obtain overall estimates. We investigated the effects following immediate (lags 0-1), delayed (lags 2-5) and prolonged exposure (lags 0-5) and effect modification patterns by season. We evaluated the sensitivity of our results to co-pollutant exposures or city-specific model choice. We applied threshold models to investigate the pattern of selected associations. For a 10μg/m(3) increase in two days' PM2.5 exposure there was a 1.23% (95% confidence interval (95% CI): -1.63%, 4.17%) increase in diabetes deaths, while six days' exposure statistically significantly increased cardiac deaths by 1.33% (95% CI: 0.27, 2.40%), COPD deaths by 2.53% (95% CI: -0.01%, 5.14%) and LRTI deaths by 1.37% (95% CI: -1.94%, 4.78%). PM2.5 results were robust to co-pollutant adjustments and alternative modeling approaches. Stronger effects were observed in the warm season. Coarse particles displayed positive, even if not statistically significant, associations with mortality due to diabetes and cardiac causes that were more variable depending on exposure period, co-pollutant and seasonality adjustment. Our findings provide support for positive associations between PM2.5 and mortality due to diabetes, cardiac causes, COPD, and to a lesser degree to cerebrovascular causes, in the European Mediterranean region, which seem to drive the particles short-term health effects.