title: Chemical properties of air pollutants and cause-specific hospital admissions among the elderly in Atlanta, Georgia.
abstract: BACKGROUND
  Health risks differ by fine particle (aerodynamic diameter ≤ 2.5 μm) component, although with substantial variability. Traditional methods to assess component-specific risks are limited, suggesting the need for alternative methods.
  
  
  OBJECTIVE
  We examined whether the odds of daily hospital admissions differ by pollutant chemical properties.
  
  
  METHODS
  We categorized pollutants by chemical properties and examined their impacts on the odds of daily hospital admissions among Medicare recipients > 64 years of age in counties in Atlanta, Georgia, for 1998-2006. We analyzed data in two stages. In the first stage we applied a case-crossover analysis to simultaneously estimate effects of 65 pollutants measured in the Aerosol Research and Inhalation Epidemiology Study on cause-specific hospital admissions, controlling for temperature and ozone. In the second stage, we regressed pollutant-specific slopes from the first stage on pollutant properties. We calculated uncertainty estimates using a bootstrap procedure. We repeated the two-stage analyses using coefficients from first-stage models that included single pollutants plus ozone and meteorological variables only. We based our primary analyses on exposures on day of admission.
  
  
  RESULTS
  We found that 24-hr transition metals and alkanes were associated with increased odds [0.26%; 95% confidence interval (CI), 0.02-0.48; and 0.37%; 95% CI, 0.04-0.72, respectively] of hospital admissions for cardiovascular disease (CVD). Transition metals were significantly associated with increased hospital admissions for ischemic heart disease, congestive heart failure, and atrial fibrillation. Increased respiratory-related hospital admissions were significantly associated with alkanes. Aromatics and microcrystalline oxides were significantly associated with decreased CVD- and respiratory-related hospital admissions.
  
  
  CONCLUSIONS
  The two-stage approach showed transition metals to be consistently associated with increased odds of CVD-related hospital admissions.
authors.affiliation: Environmental Health Program, NORC at the University of Chicago, Newton, Massachusetts, USA.
authors.forename: Helen H
authors.initials: HH
authors.lastname: Suh
authors.forename: Antonella
authors.initials: A
authors.lastname: Zanobetti
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Brent A
authors.initials: BA
authors.lastname: Coull
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000633:toxicity*; D000473:Alkanes / Q000633:toxicity; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology; D016001:Confidence Intervals; D005260:Female; D005845:Georgia / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D028561:Transition Elements / Q000633:toxicity
chemical_list: D000393:Air Pollutants; D000473:Alkanes; D028561:Transition Elements