Senior Airman Bryant Ash, 99th Communication Squadron, places his gas mask’s drinking tube in the stored position during a chemical, biological, radiological and nuclear defense survival skills training course at Nellis Air Force Base, Nev., April 30, 2015. CBRN training refreshes Airmen in the proper procedures to take if in contact with a contaminated substance. (U.S. Air Force photo by Airman 1st Class Jake Carter)