U.S. Air Force Senior Airman Jessica Kettering, 633rd Medical Group bioenvironmental engineering technician, straps on her full-encapsulating suit during a training exercise at Langley Air Force Base, Va., May 16, 2013. Because the suit is completely sealed, responders wear air tanks and masks in order to breathe. (U.S. Air Force photo by Airman 1st Class Austin Harvill/Released)