U.S Air Force Airman Alex McClendon, 633rd Aerospace Medicine Squadron bioenvironmental engineer technician, tests a water sample for potential hydrogen at Langley Air Force Base, Va., Feb. 9, 2016. Bioenvironmental Airmen conduct air, water, noise and radiation sampling for numerous facilities around the base. (U.S. Air Force photo by Senior Airman Brittany E. N. Murphy)