140313-F-CX352-034

U.S. Air Force Senior Airman Paville Aldridge, 20th Aerospace Medicine Squadron Aerospace and Operational Physiology technician, instructs students on the symptoms of hypoxia, Shaw Air Force Base, S.C., March 13, 2014. Hypoxia is caused by the lack of oxygen in the blood. (U.S. Air Force photo by Airman 1st Class Jonathan Bass/Released)

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