Tech. Sgt. Dave Rivera, 99th Medical Group, holds his gas mask in place on his face during a chemical, biological, radiological and nuclear defense survival skills training course on Nellis Air Force Base, Nev., April 30, 2015. The course consists of individual and team demonstration performance objectives that provide hands-on training and evaluation of knowledge acquired. (U.S. Air Force photo by Airman 1st Class Mikaley Towle)
Airman 1st Class Mikaley Towle
Taken on 30 April 2015
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