U.S. Marines with Corporals Course 4-19, Headquarters

U.S. Marines with Corporals Course 4-19, Headquarters and Support Battalion, Marine Corps Installations West, Marine Corps Base Camp Pendleton, prepare to clear their gas mask during a gas chamber qualification at the 33 Area gas chamber on MCB Camp Pendleton, California, Sept. 30, 2019. During the qualification, Marines are taught nuclear, biological and chemical threats, reactions to NBC attacks, and how to take care of and use a gas mask. Corporals Course 4-19 is scheduled to graduate on October 4, 2019. (U.S. Marine Corps photo by Lance Cpl. Alison Dostie)