title: Acute and chronic effects of particles on hospital admissions in New-England.
abstract: BACKGROUND
  Many studies have reported significant associations between exposure to PM(2.5) and hospital admissions, but all have focused on the effects of short-term exposure. In addition all these studies have relied on a limited number of PM(2.5) monitors in their study regions, which introduces exposure error, and excludes rural and suburban populations from locations in which monitors are not available, reducing generalizability and potentially creating selection bias.
  
  
  METHODS
  Using our novel prediction models for exposure combining land use regression with physical measurements (satellite aerosol optical depth) we investigated both the long and short term effects of PM(2.5) exposures on hospital admissions across New-England for all residents aged 65 and older. We performed separate Poisson regression analysis for each admission type: all respiratory, cardiovascular disease (CVD), stroke and diabetes. Daily admission counts in each zip code were regressed against long and short-term PM(2.5) exposure, temperature, socio-economic data and a spline of time to control for seasonal trends in baseline risk.
  
  
  RESULTS
  We observed associations between both short-term and long-term exposure to PM(2.5) and hospitalization for all of the outcomes examined. In example, for respiratory diseases, for every 10-µg/m(3) increase in short-term PM(2.5) exposure there is a 0.70 percent increase in admissions (CI = 0.35 to 0.52) while concurrently for every 10-µg/m(3) increase in long-term PM(2.5) exposure there is a 4.22 percent increase in admissions (CI = 1.06 to 4.75).
  
  
  CONCLUSIONS
  As with mortality studies, chronic exposure to particles is associated with substantially larger increases in hospital admissions than acute exposure and both can be detected simultaneously using our exposure models.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America. ekloog@hsph.harvard.edu
authors.forename: Itai
authors.initials: I
authors.lastname: Kloog
authors.forename: Brent A
authors.initials: BA
authors.lastname: Coull
authors.forename: Antonella
authors.initials: A
authors.lastname: Zanobetti
authors.forename: Petros
authors.initials: P
authors.lastname: Koutrakis
authors.forename: Joel D
authors.initials: JD
authors.lastname: Schwartz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000633:toxicity*; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000453:epidemiology; D004781:Environmental Exposure; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009511:New England / Q000453:epidemiology; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*; D012044:Regression Analysis; D012140:Respiratory Tract Diseases / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter