title: Epidemiologic evidence of a relationship between airway hyperresponsiveness and exposure to polluted air.
abstract: BACKGROUND
  There has been an increase in allergic diseases as a result of increased air pollution emanating from traffic and various industries.
  
  
  OBJECTIVE
  This study evaluated the association between air pollution and airway hyperresponsiveness in a cross-sectional study of a cohort of 670 children, aged 10-13 years.
  
  
  METHODS
  We measured spirometry and conducted allergic skin tests and methacholine challenge tests in 670 schoolchildren. The methacholine concentration causing a 20% fall in FEV1 (PC20) was used as the threshold of airway hyperresponsiveness (AHR). Thresholds of 16 mg/dl or less were assumed to indicate AHR.
  
  
  RESULTS
  All of the schoolchildren had normal pulmonary function. Of the children, 257 (38.3%) had AHR. There was a significant increase in AHR in schoolchildren living near a chemical factory [45.0% (138/306), 6.50 +/- 0.48] compared to those in rural [31.9% (52/163), 9.84 +/- 0.83] and coastal [33.3% (67/201), 7.17 +/- 0.68] areas. Atopy was significantly more prevalent near the chemical factory vs the coastal and rural areas [35.6% (109/306) vs 27.3% (55/201) and 23.3% (38/163), respectively, P < 0.007]. Schoolchildren with atopy had lower PC20 than those without atopy (5.98 +/- 0.60 vs 8.15 +/- 0.45, P < 0.001). Positive allergy skin tests and living in a polluted area were risk factors in multivariate analyses adjusted for sex, parents' smoking habits, age, body mass index, nose symptoms and lung symptoms (odds ratio for location = 2.4875, confidence interval 1.6542-3.7406, P < 0.000; odds ratio for allergy skin test = 1.5782, confidence interval 1.1130-2.2379, P < 0.0104).
  
  
  CONCLUSIONS
  Our findings demonstrate that more children living in polluted areas have airway hyperresponsiveness than do those living in less polluted areas.
authors.affiliation: Department of Internal Medicine, Soonchunhyang University Hospital, Bucheon, Korea.
authors.forename: A-S
authors.initials: AS
authors.lastname: Jang
authors.forename: C-H
authors.initials: CH
authors.lastname: Yeum
authors.forename: M-H
authors.initials: MH
authors.lastname: Son
mesh_terms: D000293:Adolescent; D000393:Air Pollutants / Q000009:adverse effects*; D000485:Allergens / Q000009:adverse effects; D002648:Child; D002669:Child Welfare; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D007723:Korea / Q000453:epidemiology; D008168:Lung / Q000187:drug effects / Q000502:physiology; D008297:Male; D009585:Nitrogen Dioxide / Q000009:adverse effects; D015995:Prevalence; D012130:Respiratory Hypersensitivity / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D012882:Skin Tests; D013223:Statistics as Topic; D013458:Sulfur Dioxide / Q000009:adverse effects
chemical_list: D000393:Air Pollutants; D000485:Allergens; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide