Arizona Army National Guard Soldiers from the 2220th Transportation Company are engulfed by colored smoke after putting on their protective masks during a simulated chemical attack August 5, 2017 at Florence Military Reservation in Florence, Ariz. The Guardsmen conducted nuclear, biological and chemical warfare training which included entering a gas chamber and being exposed to CS tear gas.
(U.S. Army National Guard photo by Staff Sgt. Brian A. Barbour). Original public domain image from Flickr