Senior Airman Tony Pauline, 779th Aerospace Medical Squadron bioenvironmental engineering technician, scans an office desk for a potential chemical agent during a training exercise in the Memorial Tunnel at the Center for National Response in Gallagher, WV., March 17, 2015. This training is part of the annual Black Flag exercise for first responders. Pauline is stationed at Joint Base Andrews, Md. (U.S. Air Force photo/Senior Airman Joshua R. M. Dewberry)