| Introduction. Civilian aircraft fly at cabin pressure equivalents that correspond to altitudes of greater or equal to 2400m above sea level. The question arose whether hypobaric hypoxia impairs normal human olfactory function.;Methods. 17 healthy volunteers (15 male, 2 female; age: mean: 35.7y, range: 27--53y, SD: 7.3) were subjected to olfactory threshold testing using vanillin as test substance in a quantitative olfactory threshold testing device (Givaudan Dubendorf Ltd, CH 8600 Dubendorf, Switzerland). The threshold was tested first under normoxia (breathing room air at 440 meters above sea level (m.a.s.l.)) and then under hypobaric hypoxia conditions (target pulse oximetry: 65--70%) in the hypobaric chamber of the Swiss Air Force Institute of Aviation Medicine in Dubendorf, Switzerland.;Results. 14 out of 17 subjects experienced a decrease in their olfactory threshold (p = 0.01). In 3 subjects there was no olfactory threshold shift. No subject experienced an improvement of their olfactory threshold under hypoxia.;Conclusions. Hypobaric hypoxia decreases the human olfactory threshold for vanillin. |
