Facial hair is prohibited for most airline pilots because of the widespread belief that the seal on oxygen masks might be rendered ineffective, preventing aircrews from performing their duties during emergencies. Continuous oximetry recordings were made every second from 24 volunteers wearing a standard commercial airline mask in one of 3 beard conditions: no beards, short beards (< 10 mm in length) and long beards (> 10 mm in length) in a normobaric hypoxia chamber at 30,000 ft (10,000 m). Masks were worn in the chamber for about 10 minutes before being removed for about 2 minutes to experience hypoxia. Once returned to normoxia, volunteers were exposed to smelling salts held directly under the chin. None of the beard conditions differed in the time to don the masks. There were no differences in the arterial saturation percent of oxygen (SpO2) between beard conditions for either mask-on or mask-off segments in the chamber. There were significant differences in SpO2 comparing the mask-on segment to the mask-off segment, indicating that hypoxemic conditions would have been detected had the masks been ineffective. Using a current on-demand airline oxygen mask, SpO2 levels were never compromised by any of the beard conditions. Because the highly volatile smelling salts were imperceptible through the masks, smoke and other noxious irritants would not be perceived. These results support the contention that airline pilots with beards of any length would not be impaired by hypoxia or smoke while dealing with an inflight emergency.