U.S. Air Force Service members put on personal-protective equipment for a simulated emergency during a Hazardous Materials Awareness and Operations course at Langley Air Force Base, Va., Aug. 13, 2014. The exercise taught students how to respond in the event of a chemical crisis and while performing operations in a Vapor-tight HAZMAT suit. (U.S. Air Force photo by Senior Airman Connor Estes/Released)