Difference in the relation between daily mortality and air pollution among elderly and all-ages populations in southwestern France

Numerous time series studies around the world have reported an association between mortality and particulate air pollution. We investigated the distribution over time of effect of air pollution on short-term mortality among subjects aged 65 years and older and of all ages in Bordeaux, France. Statistical analysis was based on generalized additive models using either loess or penalized spline smoothing. Our study found a significant positive association between air pollution and all nonaccidental mortality and specific mortality in both group of population (all ages and elderly) with a greater effect among the elderly, particularly for respiratory mortality. For this case, we observed a greater effect according to distributed lag models (0–5 days) among the elderly, with an estimated increase of 9.2% in the daily number of deaths for 10 μg/m3 of daily black smoke [95% CI, 3.4–15.3]. These results contribute to the efforts made to understand how air pollution promotes adverse health effects and to identify susceptible subgroups.