U.S. Air Force Airman 1st Class Zachary Day, 633rd Civil Engineer Squadron emergency manager, tests the simulated hazard zone at Langley Air Force Base, Va., Dec. 18, 2013. The 633rd CES paired up with the 633rd Aerospace Medicine Squadron bioenvironmental engineering team to practice real-world situations. Day hails from Owensboro, Ky. (U.S. Air Force photo by Airman 1st Class Victoria H. Taylor/Released)