Breathing oxygen
SOUTHWEST ASIA -- Tech. Sgt. William McLeod (left) monitors the vented liquid oxygen, while Staff Sgt. Anthony Anderson monitors the gages of an oxygen servicing cart. Oxygen remains in a liquid form at temperatures below minus 297 degrees Fahrenheit. At ambient temperatures, the oxygen boils and releases air-breathable oxygen, which is normally used in pressurized aircraft. Both airmen are at a forward-deployed location. Anderson is from the 60th Logistics Readiness Squadron at Travis Air Force Base, Calif., and McLeod is from the 99th Supply Squadron at Nellis AFB, Nev. (U.S. Air Force photo by Master Sgt. Lance Cheung)