title: Air pollution and emergency department visits for otitis media: a case-crossover study in Edmonton, Canada.
abstract: BACKGROUND
  Otitis media (OM) is one of the most common early childhood infections, resulting in an enormous economic burden to the health care system through unscheduled doctor visits and antibiotic prescriptions.
  
  
  OBJECTIVE
  The objective of this study was to investigate the potential association between ambient air pollution exposure and emergency department (ED) visits for OM.
  
  
  METHODS
  Ten years of ED data were obtained from Edmonton, Alberta, Canada, and linked to levels of air pollution: carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide, and particulate matter (PM) of median aerometric diameter < or = 10 and 2.5 pm (PM10 and PM2.5 respectively). A time-stratified case-crossover technique was applied to analyze the associations between ambient air pollution and health outcomes. Conditional logistic regression analysis with the subject's identification number as a stratum variable was used to obtain odds ratios (ORs) and their corresponding 95% confidence intervals after adjustment for meteorological factors.
  
  
  RESULTS
  We based the analysis on 14,527 ED visits for OM over 10 years in children 1-3 years of age. We observed statistically significant positive associations between ED visits for OM and interquartile increases in CO and NO2 levels after adjusting for ambient temperature and relative humidity. We observed the strongest associations (expressed by ORs) in the warmer months (April-September) in girls and all patients for exposure to CO and NO2, and in boys for exposure to CO, for 2 days before an OM ED visit.
  
  
  CONCLUSIONS
  These results support the hypothesis that ED visits for OM are associated with ambient air pollution.
authors.affiliation: Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Roger
authors.initials: R
authors.lastname: Zemek
authors.forename: Mieczysław
authors.initials: M
authors.lastname: Szyszkowicz
authors.forename: Brian H
authors.initials: BH
authors.lastname: Rowe
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000706:statistics & numerical data*; D000416:Alberta; D002248:Carbon Monoxide / Q000032:analysis; D002675:Child, Preschool; D018592:Cross-Over Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D007223:Infant; D019570:Inhalation Exposure / Q000032:analysis / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis; D016017:Odds Ratio; D010033:Otitis Media / Q000453:epidemiology*; D010126:Ozone / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis; D012307:Risk Factors; D013458:Sulfur Dioxide / Q000032:analysis; D014887:Weather
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide