Army Sgt. 1st Class Anastassia C. Doctor applies an M40 field protective mask while conducting chemical, biological, radiological and nuclear sustainment training on Joint Base Elmendorf-Richardson, Alaska, July 16, 2015. Doctor is assigned to Company C, 307th Expeditionary Signal Battalion. Army Sgt. 1st Class Anastassia C. Doctor applies an M40 field protective mask while conducting chemical, biological, radiological and nuclear sustainment training on Joint Base Elmendorf-Richardson, Alaska, July 16, 2015. Doctor is assigned to Company C, 307th Expeditionary Signal Battalion. SHARE: Download: Full Size (2.265916 MB) Tags: photo essays Credit: VIRIN: 984919-X-ONA12-356.jpg Photo Gallery