Airman 1st Class Harley Love-Hall, 51st Civil Engineer Squadron firefighter, prepares to put on his gas mask during a simulated mass casualty exercise May 12, 2015, at Osan Air Base, Republic of Korea. Members of Team Osan are participating in the combat exercise in order to focus on readiness, test Osan’s wartime procedures, and realistically look at our ability to defend the base, execute operations and receive follow-on forces. (U.S. Air Force photo by Staff Sgt. Benjamin Sutton/Released)