title: Childhood visits to animal buildings and atopic diseases in adulthood: an age-dependent relationship.
abstract: BACKGROUND
  Several studies reported protective effects of farming environments against atopic diseases. Therefore, we aimed to establish the relevant timing of exposure in early life.
  
  
  METHODS
  A cross-sectional study was carried out in a rural town. Overall, 4,537 inhabitants aged 18-44 years were eligible. Of these, 3,112 (69%) responded to a postal questionnaire on atopic diseases, life-time exposure to farming environments, and potential confounders.
  
  
  RESULTS
  Those with regular childhood exposure to animal buildings had a significantly reduced risk of nasal allergies. The greatest reduction in risk was seen for respondents starting regular visits to animal stables during the 1st year of life or between ages 3 and 5. Participants reporting start of exposure after age 5 remained at a lower risk for nasal allergies (0.70, 0.49-1.01).
  
  
  CONCLUSIONS
  The preventive effect of animal buildings' exposure against atopic respiratory diseases continues into adulthood. The magnitude of the effect appears to be age-dependent.
authors.affiliation: Institute for Occupational and Environmental Medicine, Unit for Occupational and Environmental Epidemiology & Net Teaching, Ludwig-Maximilians-University, Munich, Germany. katja.radon@med.uni-muenchen.de
authors.forename: Katja
authors.initials: K
authors.lastname: Radon
authors.forename: Vera
authors.initials: V
authors.lastname: Ehrenstein
authors.forename: Georg
authors.initials: G
authors.lastname: Praml
authors.forename: Dennis
authors.initials: D
authors.lastname: Nowak
mesh_terms: D000328:Adult; D000367:Age Factors; D000822:Animal Husbandry; D000818:Animals; D000829:Animals, Domestic; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects* / Q000517:prevention & control; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D011795:Surveys and Questionnaires