title: Air pollution and ED visits for asthma in Australian children: a case-crossover analysis.
abstract: OBJECTIVE
  We aimed to determine the effects of ambient air pollutants on emergency department (ED) visits for asthma in children.
  
  
  METHODS
  We obtained routinely collected ED visit data for asthma (ICD9 493) and air pollution (PM(10), PM(2.5), O(3), NO(2), CO and SO(2)) and meteorological data for metropolitan Sydney for 1997-2001. We used the time stratified case-crossover design and conditional logistic regression to model the association between air pollutants and ED visits for four age-groups (1-4, 5-9, 10-14 and 1-14 years). Estimated relative risks for asthma ED visits were calculated for an exposure corresponding to the inter-quartile range in pollutant level. We included same day average temperature, same day relative humidity, daily temperature range, school holidays and public holidays in all models.
  
  
  RESULTS
  Associations between ambient air pollutants and ED visits for asthma in children were most consistent for all six air pollutants in the 1-4 years age-group, for particulates and CO in the 5-9 years age-group and for CO in the 10-14 years age-group. The greatest effects were most consistently observed for lag 0 and effects were greater in the warm months for particulates, O(3) and NO(2). In two pollutant models, effect sizes were generally smaller compared to those derived from single pollutant models.
  
  
  CONCLUSIONS
  We observed the effects of ambient air pollutants on ED attendances for asthma in a city where the ambient concentrations of air pollutants are relatively low.
authors: Centre for Research, Evidence Management and Surveillance, Sydney South West Area Health Service, Liverpool, NSW, Australia. b.jalaludin@unsw.edu.au
authors: Bin
authors: B
authors: Jalaludin
authors: Behnoosh
authors: B
authors: Khalaj
authors: Vicky
authors: V
authors: Sheppeard
authors: Geoff
authors: G
authors: Morgan
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D001249:Asthma / Q000209:etiology*; D001315:Australia; D002648:Child; D002675:Child, Preschool; D018592:Cross-Over Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007223:Infant; D016015:Logistic Models; D009517:New South Wales; D014504:Urban Health