TUNNEL HILL, Ga. - Lance Cpl. Tyler Kuehn, a hazmat technician with Chemical Biological Radiological Nuclear Platoon, Combat Logistics Regiment 4, 4th Marine Logistics Group, Marine Forces Reserve, adjusts his gas mask during a CBRN training exercise at Volunteer Training Site, Catoosa, Tunnel Hill, Ga., April 4, 2017. The CBRN Marines check their masks every time they put on any of their suits to ensure their mask will provide clean oxygen for up to an hour while they are in an unknown area. (U.S. Marine Corps photo by Cpl. Devan Alonzo Barnett/Released)