title: Ambient ozone exposure is associated with eosinophil activation in healthy children.
abstract: BACKGROUND
  Eosinophil activation is characteristic for allergic airways disease. However, eosinophilic airways inflammation has also been observed subsequent to ambient ozone exposure.
  
  
  METHODS
  For a population sample of 877 children living at nine sites with different ozone exposure we measured urinary eosinophil protein X (U-EPX) as a marker of eosinophil activation. U-EPX was determined from a single spot urine sample during autumn 1997. Children were participants in a longitudinal study of ozone effects on lung function.
  
  
  RESULTS
  The 5-95% percentiles of ozone exposure (30-day mean before test) were 11.8-51.5 p.p.b. (mean: 31.6 ppb). U-EPX was measured by radioimmunoassay and expressed as ratio to urinary creatinine (microg EPX/mmol creatinine). Log transformation was performed to achieve a normal distribution. LogU-EPX was associated with gender, a diagnosis of asthma and atopy (skin test sensitivity to any of seven aeroallergens). LogU-EPX increased with ozone exposure for all children. The medians of LogU-EPX according to the first-fourth quartiles of ozone exposure were: 1.82, 1.88, 1.95 and 2.03. For 172 non-asthmatic children who had spent the whole summer at their site corresponding figures were 1.57, 1.78, 2.07 and 2.13. In a multivariate model with logU-EPX being the dependent variable and adjusted for gender, site and atopy, ozone was found to be significant (estimate: 0.007 microg/mmol creatinine per ppb ozone; SE:0.02; P < 0.001).
  
  
  CONCLUSIONS
  Our observation supports the hypothesis that ozone in healthy children is associated with eosinophil inflammation, most likely in the airways.
authors.affiliation: University Children's Hospital Vienna, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Frischer
authors.forename: M
authors.initials: M
authors.lastname: Studnicka
authors.forename: G
authors.initials: G
authors.lastname: Halmerbauer
authors.forename: F
authors.initials: F
authors.lastname: Horak
authors.forename: C
authors.initials: C
authors.lastname: Gartner
authors.forename: E
authors.initials: E
authors.lastname: Tauber
authors.forename: D Y
authors.initials: DY
authors.lastname: Koller
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects / Q000276:immunology*; D002648:Child; D003430:Cross-Sectional Studies; D047208:Eosinophil-Derived Neurotoxin; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D010126:Ozone / Q000009:adverse effects / Q000276:immunology*; D012260:Ribonucleases / Q000652:urine
chemical_list: D000393:Air Pollutants; D010126:Ozone; D047208:Eosinophil-Derived Neurotoxin; D012260:Ribonucleases