I don't know about "Boot Camp" but in U.S. Army Basic Combat Training, every recruit that goes through it undergoes NBC (nuclear, biological, and chemical) warfare training. Part of this training is to spend time in the "gas chamber" (just a room, really). You will learn how not to panic and to continue to to your job in a chemical environment.
There will be a lot of tears and mucous but once you're in the fresh air you'll recover in a minute or so. Hint: remember not to rub your eyes no matter how much you want to.
Other things you'll learn in BCT include the following:
Some general knowledge about the rank system, communications, creed, code of conduct, etc.
Uniforms, equipment, weapons, land navigation, military courtesy, drill and ceremonies, first aid, and of course benefits are also taught.
Don't worry about the gas, we all have been through it, some of us many times and while uncomfortable, it's just another aspect of training. It makes you a better soldier.