28th Maintenance Squadron Additive Manufacturing Rapid Repair Facility Airmen put on gas masks at the South Dakota Air and Space Museum in Box Elder, S.D., Sept. 18, 2019. The Airmen must wear protective gear so the spherical aluminum particles that shoot out at supersonic speeds do not get into their lungs, as well as the other gases used. (U.S. Air Force photo by Airman Quentin K. Marx)