Senior Airman Ebony T. Hills, a bioenvironmental journeyman assigned to the 315th Airlift Wing Aerospace Medicine Squadron, performs a gas mask fit test on Staff Sgt. Shawn H. Osz, an aircraft fuel systems specialist with the 315 AW Maintenance Squadron here at Joint Base Charleston, Air Base, S.C., October 14, 2012. Hills was selected as the MAJCOM 2011 Outstanding Bioenvironmental Engineering Airman of the Year. Sections of this photo were blurred for security purposes. U.S. Air Force photo by SrA. Bobby Pilch.