Staff Sgt. Nathan Maysonet, 47th Flying Training Wing public affairs photojournalist, completes his fit test for the M50 chemical protective mask at the 47th Medical Operations Squadron Bioenvironmental Engineering office on Laughlin Air Force Base, Texas, Jan. 12, 2015. The fit test requires the user to don their own mask and perform a series of exercises that simulate typical activities to ensure the mask fits properly and provides a good seal. (U.S. Air Force photo by Airman 1st Class Ariel D. Delgado)