A medic with the 82nd Airborne Division’s 1st Brigade Combat Team wearing a gas mask prepares to enter a chamber of tear gas during training Oct. 3, 2011, at Fort Bragg, N.C. Soldiers must periodically show they are proficient at donning and sealing a gas mask under the duress of contact with a gas irritant such as tear gas. (U.S. Army photo by Sgt. Michael J. MacLeod)