Seasonal and regional short-term effects of fine particles on hospital admissions in 202 US counties, 1999-2005.
The authors investigated whether short-term effects of fine particulate matter with an aerodynamic diameter < or =2.5 microm (PM(2.5)) on risk of cardiovascular and respiratory hospitalizations among the elderly varied by region and season in 202 US counties for 1999-2005. They fit 3 types of time-series models to provide evidence for 1) consistent particulate matter effects across the year, 2) different particulate matter effects by season, and 3) smoothly varying particulate matter effects throughout the year. The authors found statistically significant evidence of seasonal and regional variation in estimates of particulate matter effect. Respiratory disease effect estimates were highest in winter, with a 1.05% (95% posterior interval: 0.29, 1.82) increase in hospitalizations per 10-microg/m(3) increase in same-day PM(2.5). Cardiovascular diseases estimates were also highest in winter, with a 1.49% (95% confidence interval: 1.09, 1.89) increase in hospitalizations per 10-microg/m(3) increase in same-day PM(2.5), with associations also observed in other seasons. The strongest evidence of a relation between PM(2.5) and hospitalizations was in the Northeast for both respiratory and cardiovascular diseases. Heterogeneity of PM(2.5) effects on hospitalizations may reflect seasonal and regional differences in emissions and in particles' chemical constituents. Results can help guide development of hypotheses and further epidemiologic studies on potential heterogeneity in the toxicity of constituents of the particulate matter mixture.
Yale University, New Haven, CT 06511, USA. michelle.bell@yale.edu
Michelle L
ML
Bell
Keita
K
Ebisu
Roger D
RD
Peng
Jemma
J
Walker
Jonathan M
JM
Samet
Scott L
SL
Zeger
Francesca
F
Dominici
D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects; D000465:Algorithms; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000209:etiology; D003627:Data Interpretation, Statistical; D016208:Databases, Factual; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D006278:Medicare / Q000706:statistics & numerical data; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects*; D010343:Patient Admission / Q000706:statistics & numerical data; D012140:Respiratory Tract Diseases / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D012621:Seasons; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D000393:Air Pollutants; D052638:Particulate Matter