U.S. Army Soldiers assigned to the 689th Rapid Port Opening Element, 832nd Transportation Battalion, 597th Transportation Brigade receive refresher training on their gas mask at Fort McCoy, Wisconsin, Sept. 7, 2018. The Soldiers and U.S. Air Force Airmen carried their gas mask with them 24 hours a day in the event of a simulated chemical attack. (U.S. Air Force photo by Senior Airman Derek Seifert)