title: Short-term exposure to hypoxia for work and leisure activities in health and disease: which level of hypoxia is safe?
abstract: BACKGROUND
  Exposures to natural and simulated altitudes entail reduced oxygen availability and thus hypoxia. Depending on the level of hypoxia, the duration of exposure, the individual susceptibility, and preexisting diseases, health problems of variable severity may arise. Although millions of people are regularly or occasionally performing mountain sport activities, are transported by airplanes, and are more and more frequently exposed to short-term hypoxia in athletic training facilities or at their workplace, e.g., with fire control systems, there is no clear consensus on the level of hypoxia which is generally well tolerated by human beings when acutely exposed for short durations (hours to several days).
  
  
  CONCLUSIONS
  Available data from peer-reviewed literature report adaptive responses even to altitudes below 2,000 m or corresponding normobaric hypoxia (F(i)O(2) > 16.4%), but they also suggest that most of exposed subjects without severe preexisting diseases can tolerate altitudes up to 3,000 m (F(i)O(2) > 14.5%) well. However, physical activity and unusual environmental conditions may increase the risk to get sick. Large interindividual variations of responses to hypoxia have to be expected, especially in persons with preexisting diseases. Thus, the assessment of those responses by hypoxic challenge testing may be helpful whenever possible.
authors.affiliation: Department of Sport Science, Medical Section, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria. martin.burtscher@uibk.ac.at
authors.forename: Martin
authors.initials: M
authors.lastname: Burtscher
authors.forename: Klemens
authors.initials: K
authors.lastname: Mairer
authors.forename: Maria
authors.initials: M
authors.lastname: Wille
authors.forename: Hannes
authors.initials: H
authors.lastname: Gatterer
authors.forename: Gerhard
authors.initials: G
authors.lastname: Ruedl
authors.forename: Martin
authors.initials: M
authors.lastname: Faulhaber
authors.forename: Günther
authors.initials: G
authors.lastname: Sumann
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000401:Aircraft; D000472:Alkalosis, Respiratory / Q000503:physiopathology; D000532:Altitude Sickness / Q000503:physiopathology*; D001274:Atmospheric Pressure; D006305:Health Status Indicators; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D007899:Leisure Activities; D009043:Motor Activity / Q000502:physiology; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D013564:Sympathetic Nervous System / Q000503:physiopathology