A soldier assigned to Headquarters and Headquarters Detachment, 59th Signal Battalion, checks the seal on his protective mask during Nuclear Biological Chemical training on Joint Base Elmendorf-Richardson, Alaska, Thursday, 2014. The training culminated with masked Soldiers entering a sealed chamber filled with CS, then removing their protective gear to promote confidence in their equipment. CS, technically known as 0 chlorobenzalmalononitrile, is a solid white powder mixed with a dispersal agent and commonly referred to as tear gas. (U.S. Air Force photo/Justin Connaher)