Short-Term Associations Between Fine and Coarse Particles and Cardiorespiratory Hospitalizations in Six French Cities

Abstract

ISEE-481 Objective: To estimate the links between fine particles (FP, particles with diameter <2.5 μm) and coarse particles (CP, >2.5 and <10 μm) levels and cardiorespiratory hospitalizations in 6 French cities during the 2000 to 2003 period. Material and Methods: Daily CP levels were obtained for each background monitoring station by subtracting PM2.5 levels from PM10. Daily numbers of hospitalizations for respiratory, cardiovascular, cardiac and ischemic heart diseases were extracted from the French hospital information system. Associations between exposure indicators and hospitalizations were estimated in each city using a Poisson regression model, controlling for well-known confounding factors and temporal trends. City-specific findings were combined to obtain excess relative risks (ERRs) associated with a 10 μg/m3 increase in FP and CP levels. Results: The correlation coefficient between FP and CP ranged from 0.28 and 0.73, depending on the city. Positive associations were observed between FP levels and every cardiovascular indicator, although some did not reach significance. These associations were stronger in people ≥65 years of age, and when only hospitalizations for ischemic heart diseases were considered [ERR = 4.5%, 95% CI = 2.3%–6.8%)]. Compared with FP, associations with CP were weaker and nonsignificant except for ischemic heart diseases [ERR in the elderly = 6.4%, 1.6%–11.4%). Concerning respiratory diseases, no association was observed with FP whereas positive trends were found with CP, with a significant association in the 0 to 14 age group [ERR = 6.2% (0.4%–12.3%). Conclusions: This work contributes to a better understanding of the specific patterns of fine and coarse particles. The low correlation between the 2 fractions and the different associations observed with hospitalizations suggest different sources of exposure and effects. In accordance with others, our results point out that the coarse fraction may have a stronger effect on respiratory morbidity than the fine one, whereas fine particles could be more associated with some cardiovascular outcomes.