Staff Sgt. Candace Greene, 28th Operations Support Squadron aircrew flight equipment technician, assists Lt. Col. Jason Yeatts, 28th Operations Group deputy commander, with donning gear during aircrew chemical defense ensemble training at Ellsworth Air Force Base, S.D., May 29, 2014. The training prepares aircrew to survive and operate in a chemically contaminated environment. (U.S. Air Force photo by Senior Airman Anania Tekurio/Released)