title: Association between air pollution and acute childhood wheezy episodes: prospective observational study.
abstract: OBJECTIVE
  To examine the association between the air pollutants ozone, sulphur dioxide, and nitrogen dioxide and the incidence of acute childhood wheezy episodes.
  
  
  METHODS
  Prospective observational study over one year.
  
  
  METHODS
  District general hospital.
  
  
  METHODS
  1025 children attending the accident and emergency department with acute wheezy episodes; 4285 children with other conditions as the control group.
  
  
  METHODS
  Daily incidence of acute wheezy episodes.
  
  
  RESULTS
  After seasonal adjustment, day to day variations in daily average concentrations of ozone and sulphur dioxide were found to have significant associations with the incidence of acute wheezy episodes. The strongest association was with ozone, for which a non-linear U shaped relation was seen. In terms of the incidence rate ratio (1 at a mean 24 hour ozone concentration of 40 microg/m3 (SD=19.1)), children were more likely to attend when the concentration was two standard deviations below the mean (incidence rate ratio=3.01; 95% confidence interval 2.17 to 4.18) or two standard deviations above the mean (1.34; 1.09 to 1.66). Sulphur dioxide had a weaker log-linear relation with incidence (1.12; 1.05 to 1.19 for each standard deviation (14.1) increase in sulphur dioxide concentration). Further adjustment for temperature and wind speed did not significantly alter these associations.
  
  
  CONCLUSIONS
  Independent of season, temperature, and wind speed, fluctuations in concentrations of atmospheric ozone and sulphur dioxide are strongly associated with patterns of attendance at accident and emergency departments for acute childhood wheezy episodes. A critical ozone concentration seems to exist in the atmosphere above or below which children are more likely to develop symptoms.
authors.affiliation: Hillingdon Hospital, Middlesex.
authors.forename: R
authors.initials: R
authors.lastname: Buchdahl
authors.forename: A
authors.initials: A
authors.lastname: Parker
authors.forename: T
authors.initials: T
authors.lastname: Stebbings
authors.forename: A
authors.initials: A
authors.lastname: Babiker
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000393:Air Pollutants / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D004739:England / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D009585:Nitrogen Dioxide / Q000009:adverse effects*; D010126:Ozone / Q000009:adverse effects*; D010342:Patient Acceptance of Health Care; D011446:Prospective Studies; D012135:Respiratory Sounds; D012621:Seasons; D013458:Sulfur Dioxide / Q000009:adverse effects*
chemical_list: D000393:Air Pollutants; D013458:Sulfur Dioxide; D010126:Ozone; D009585:Nitrogen Dioxide