A redesigned continuous flow passenger oxygen mask was tested for its ability to deliver an adequate supply of oxygen at an altitude of 40,000 feet above sea level. Four male subjects participated in the study. Blood oxygen saturation (SaO2) baseline levels for hypoxic exposure were established for each subject. Immediately prior to high altitude exposure, subjects prebreathed 100% oxygen for two hours through a pressure demand type mask. The hypobaric chamber was then decompressed to a simulated altitude of 35,000 feet. Subjects switched to the passenger oxygen mask. The initial oxygen flow rate to the passenger mask came from manufacturer production performance test data. Once heart and respiratory rates and SaO2 level stabilized, chamber altitude was increased to 40,000 feet. Descent to ground level was performed in steps of 5,000 feet with SaO2 levels being established for each altitude and recommended oxygen flow. Subjects remained at each test altitude for a minimum of three minutes or until SaO2 levels stabilized. At no point during the testing did SaO2 levels approach baseline levels for hypoxic exposure. This mask design would appear to offer protection from hypoxia resulting from altitude exposure up to 40,000 feet.

The Federal Aviation Administration (FAA) requires under Federal Aviation Regulation (FAR) 121.337 that crew protective breathing equipment (PBE) for smoke and fume protection is installed aboard aircraft and that crewmembers be trained in the proper use of PBE (FAR 121.417). A variety of designs currently exist that meet the requirements of these regulations. However, the threat posed by atmospheric contamination in an environment that cannot be quickly escaped suggest that extending the protective capabilities of PBE devices beyond what is mandated by the FAA may be beneficial in aviation and other arenas. These experiments were conducted to evaluate the use of one style of PBE in terms of potential for long-term (>20 min) use and to identify issues critical to long-term use. A closed-circuit PBE device utilizing lithium hydroxide (LiOH) technology for carbon dioxide (CO2) removal was tested.