title: Biological effects of inhaled nitrogen dioxide in healthy human subjects.
abstract: OBJECTIVE
  Several epidemiological studies indicate that inhaled nitrogen dioxide (NO2) at low concentrations have been statistically associated with adverse health effects. However, these results are not reflected by exposure studies in humans. The aim of the study was to assess the acute functional and cellular responses to different NO2 concentrations in healthy human subjects with various techniques.
  
  
  METHODS
  Twenty-five subjects were exposed for 3 h to NO2 concentrations 0, 0.1, 0.5, and 1.5 ppm in a randomized crossover study design during 4 consecutive weeks. In each subject, lung function, diffusion capacity and exhaled nitric oxide were measured and inflammation markers were assessed in blood, nasal secretions, induced sputum and exhaled breath condensate.
  
  
  RESULTS
  From all lung function indices under consideration, only intrathoracic gas volume was borderline significantly increased after 0.5 ppm (p = 0.048) compared to 0.1 ppm NO2. Regarding the cellular effect parameters, the macrophage concentration in induced sputum decreased with increasing NO2 concentration, although these changes were only borderline significant (p = 0.05).
  
  
  CONCLUSIONS
  These results do not suggest a considerable acute adverse response in human subjects after 3 h of exposure to NO2 in the NO2 concentration range investigated in this study.
authors.affiliation: Institute for Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany. pbrand@ukaachen.de.
authors.forename: P
authors.initials: P
authors.lastname: Brand
authors.affiliation: Institute for Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Bertram
authors.affiliation: Department of Otolaryngology, Klinikum rechts der Isar and Center of Allergy and Environment (ZAUM), Technische Universität München, Munich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Chaker
authors.affiliation: Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: R A
authors.initials: RA
authors.lastname: Jörres
authors.affiliation: Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kronseder
authors.affiliation: Institute for Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kraus
authors.affiliation: Institute for Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Gube
mesh_terms: D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis; D019570:Inhalation Exposure / Q000009:adverse effects*; D008168:Lung / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects; D008297:Male; D009297:Nasal Mucosa / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000032:analysis; D009585:Nitrogen Dioxide / Q000633:toxicity*; D011653:Pulmonary Diffusing Capacity / Q000187:drug effects; D066232:Pulmonary Elimination / Q000187:drug effects; D012129:Respiratory Function Tests; D013183:Sputum / Q000166:cytology / Q000187:drug effects; D055815:Young Adult
chemical_list: D018836:Inflammation Mediators; D009569:Nitric Oxide; D009585:Nitrogen Dioxide
keywords: Exposure; Human subjects; Nitrogen dioxide; Systemic effects; Topic effects