Airman 1st Class Rand McCrady, 36th Munitions Squadron munitions system journeyman, wears an M-50 mask during chemical, biological, radiological and nuclear training Oct. 1, 2015, at Andersen Air Force Base, Guam. Emergency managers teach a CBRN refresher course once a month to Airmen who are preparing for a permanent change of station or deploying to medium or high-threat level duty stations. (U.S. Air Force photo by Senior Airman Joshua Smoot/Released)