Coarse and Fine Particles and Daily Mortality in Nine French Cities

Abstract

ISEE-0420 Background and Objective: Short-term effects of particles on mortality have been consistently reported. Recent research strongly suggests that fine particles (PM2.5) play a substantial role in these effects, whereas results on coarse particles (PM10–2.5) are inconsistent. Our aim was to study the association between these two size fractions and daily mortality in nine French cities during the 2000–2004 period. Methods: PM10 and PM2.5 measured at the same urban sites were used to compute daily mean levels of PM2.5 and PM10–2.5. For each city, the association between both fractions of PM and daily number of deaths (for non-traumatic, cardiovascular and cardiac causes) was estimated, first in mono-pollutant models, then in two-pollutants models, using Poisson regression models controlling for confounding factors. City-specific results were combined using random effects models. Results are presented as excess relative risks (ERR, %) for an increase of the mean interquartile range of PM2.5 (9 μg/m3) and of PM10–2.5 (5 μg/m3). Results: Mean levels of PM2.5 and PM10–2.5 varied from 13 to 19 μg/m3 and from 6 to 9 μg/m3 respectively across the cities. In mono-pollutant models, ERRs of non-traumatic mortality were significant for both size fractions: 1.3%, [95% IC: 0.9–1.7] for PM2.5 and 1.0% [0.7–1.3] for PM10–2.5. In two-pollutant models, the association was almost similar for PM2.5 (1.1% [0.7–1.5]) and slightly lower but significant for PM10–2.5 (0.5% [0.2–0.9]). ERRs linking both PM2.5 and PM10–2.5 with cardiovascular and cardiac deaths were also significant and higher Conclusion: Our results contribute to a better understanding of health effects of particles according to their size. They suggest that the levels of both fine and coarse particles currently experienced in French cities are associated with short-term mortality.