Airman Marlene Zeledon (right), samples a chemical agent during a training exercise with Staff Sgt. Yaoska Quintana (left), 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. Zeledon is an 11th Civil Engineer Squadron emergency management journeyman and Quintana is the 779th Aerospace Medical Squadron NCO in-charge of flight readiness, Joint Base Andrews, Md. (U.S. Air Force photo/Airman 1st Class Joshua R. M. Dewberry)