Cpl. Paul Krehbiel (right), the chemical, biological, radioactive and nuclear chief with 3rd Radio Battalion, helps a Marine clear CS gas from his gas mask during annual gas chamber training at Boondocker Training Area, March 25, 2014. (U.S. Marine Corps photo by Lance Cpl. Matthew Bragg) - Cpl. Paul Krehbiel (right), the chemical, biological, radioactive and nuclear chief with 3rd Radio Battalion, helps a Marine clear CS gas from his gas mask during annual gas chamber training at Boondocker Training Area, March 25, 2014. (U.S. Marine Corps photo by Lance Cpl. Matthew Bragg)