A U.S. Army Soldier assigned to the 149th Transportation Company Seaport Operations Company moves his head side-to-side to test the seal of the gas mask at Joint Base Langley-Eustis, Va., Oct. 6, 2016. The chlorobenzalmalononitrile (CS) gas that the Soldiers were exposed to can cause a burning and irritating sensation to the skin, eyes, nose, mouth and throat. (U.S. Air Force photo by Airman 1st Class Derek Seifert) (Photo by Airman 1st Class Derek Seifert)