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Risk of Reduced Crew Health and Performance Due to Hypoxia


astronauts go through a "pre-breathing" period before eva
Astronauts Michael R. (Rich) Clifford and Linda M. Godwin, the assigned space-walking mission specialists for STS-76, go through a “pre-breathing” period on the Space Shuttle Atlantis’ middeck. This practice is normal procedure for space-walkers in preparation for their Extravehicular Activity (EVA) and the wearing of their Extravehicular Mobility Units (EMU). The photograph was taken with a 35mm camera by one of the crew members.

Human exploration missions will require robust, flexible Extravehicular Activity (EVA) architecture protocols that include the use of a reduced-pressure cabin atmosphere enabling staged denitrogenation. Use of this atmosphere could result in compromised health and performance to the crewmember due to exposure to mild hypobaric hypoxia; of most concern are the potential effects on the increased intracranial pressure, visual impairment, cognitive performance, sensorimotor dysfunction, oxidative damage, and sleep quality. In addition to hypobaric hypoxia associated with staged denitrogenation, there are additional factors that can result in hypoxic exposure to the crewmember, such as cabin depressurization, Environmental Control, and Life Support System (ECLSS) failure, toxic exposure, or crewmember illness/injury.

astronauts test a Personal Cabin Pressure Altitude Monitor
Jan Zysko (left) and Rich Mizell (right) test a Personal Cabin Pressure Altitude Monitor in an altitude chamber at Tyndall Air Force Base in Florida. Zysko invented the pager-sized monitor that alerts wearers of a potentially dangerous or deteriorating cabin pressure altitude condition, which can lead to life-threatening hypoxia. Zysko is chief of the KSC Spaceport Engineering and Technology directorate’s data and electronic systems branch. Mizell is a Shuttle processing engineer. The monitor, which has drawn the interest of such organizations as the Federal Aviation Administration for use in commercial airliners and private aircraft, was originally designed to offer Space Shuttle and Space Station crew members added independent notification about any depressurization

Directed Acyclic Graph Files

+ DAG File Information (HSRB Home Page)

+ Hypoxia Risk DAG and Narrative (PDF)

+ Hypoxia Risk DAG Code (TXT)

Human Research Program

+ Risk of Reduced Crew Health and Performance Due to Hypoxia

+ 2015 November Evidence Report (MSWord)



Last Updated
Sep 26, 2023
Robert E. Lewis