We got an inside look at how United States Marine Corps recruits are exposed to tear gas during basic training. Senior video correspondent Graham Flanagan spent five days at the Marine Corps Recruit Depot in Parris Island, SC, where he observed various stages of training. Recruits are exposed to CS gas, more commonly known as tear gas. Side effects include burning on the skin and in the eyes, and profuse discharge of mucus. While wearing a gas mask, the recruits spend approximately five minutes inside a gas chamber where CS tablets are burned to create the gas.