title: Ozone is associated with cardiopulmonary and stroke emergency hospital visits in Reykjavík, Iceland 2003-2009.
abstract: BACKGROUND
  Air pollution exposure is associated with hospital admissions and emergency room visits for cardiopulmonary disease and stroke. Iceland's capital area, Reykjavik, has generally low air pollution levels, but traffic and natural sources contribute to pollution levels. The objective of this study was to investigate temporal associations between emergency hospital visits and air pollutants ozone (O3), nitrogen dioxide (NO2), and particulate matter (PM10) in the Icelandic capital area.
  
  
  METHODS
  We constructed a time series of the daily number of adults who visited the emergency room, or were acutely admitted for stroke or cardiorespiratory causes to Landspitali University Hospital 1 January 2003 - 31 December 2009 from the hospital in-patient register. We used generalized additive models assuming Poisson distribution, to analyze the daily emergency hospital visits as a function of the pollutant levels, and adjusted for meteorological variables, day of week, and time trend with splines.
  
  
  RESULTS
  Daily emergency hospital visits increased 3.9% (95% confidence interval (CI) 1.7-6.1%) per interquartile (IQR) change in average O3 the same and two previous days. For females, the increase was 7.8% (95% CI 3.6-12.1) for elderly (70+), the increase was 3.9% (95% CI 0.6-7.3%) per IQR increase of NO2. There were no associations with PM10.
  
  
  CONCLUSIONS
  We found an increase in daily emergency hospital visits associated with O3, indicating that low-level exposure may trigger cardiopulmonary events or stroke.
authors.affiliation: Centre of Public Health, University of Iceland, Stapi v/Hringbraut, Reykjavik, 101, Iceland. hkc1@hi.is
authors.forename: Hanne Krage
authors.initials: HK
authors.lastname: Carlsen
authors.forename: Bertil
authors.initials: B
authors.lastname: Forsberg
authors.forename: Kadri
authors.initials: K
authors.lastname: Meister
authors.forename: Thorarinn
authors.initials: T
authors.lastname: Gíslason
authors.forename: Anna
authors.initials: A
authors.lastname: Oudin
mesh_terms: D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D002318:Cardiovascular Diseases / Q000139:chemically induced / Q000453:epidemiology*; D015897:Comorbidity; D004636:Emergency Service, Hospital; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity; D010126:Ozone / Q000032:analysis / Q000633:toxicity; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity; D016012:Poisson Distribution; D012140:Respiratory Tract Diseases / Q000139:chemically induced / Q000453:epidemiology*; D012621:Seasons; D020521:Stroke / Q000139:chemically induced / Q000453:epidemiology; D013997:Time Factors; D014504:Urban Health
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D010126:Ozone; D009585:Nitrogen Dioxide