MARINE CORPS AIR STATION YUMA, Ariz. -- U.S. Marines stationed at Marine Corps Air Station (MCAS) Yuma, conduct their annual Chemical, Biological, Radiological, and Nuclear Defense (CBRN) training at MCAS Yuma, Ariz. Gas Chamber May 9, 2019. The gas chamber is a controlled environment in which a non-lethal gas is released, this trains Marines to have confidence in their gear and become familiar with the M50 Gas Mask and the effects of the gas. (U.S. Marine Corps photo by Pfc. John Hall)