Everyone goes into the gas chamber in bootcamp, that is just the way it is, it's part of the training.
The sole purpose of the gas chamber is to introduce the recruit to NBC Nuclear, Biological and Chemical training and the usage of the basic equipment to exist and function in these environments. Instead of putting recruits into a room and tossing Mustard Gas or a Nerve Agent, CS Gas or "Tear Gas" is used as a less than lethal agent to simulate an environment. CS gas won't kill you but it will make your morning less than pleasant.
In my day, the Gas Chamber exercise was a bit different than what they do today. In my day they had an extra twist, I will explain.
They herded us into the chamber with Gas Masks on as normal and instructed us on the purpose of the exercise.
I remember standing there thinking, what could possibly go wrong here! Well, the instructor in the center began to enact the CS agent and the room filled with a light mist of smoke. At first there wasn't an issue, but then the exposed skin on my body began to burn, that is also a reaction to CS gas, exposed flesh is irritated.. Ok, no big deal right, "Marines" I can handle a little burning sensation, it's not like I was on fire !!
It is at this point the real fun begins, while all of our exposed skin is tingling, we are then instructed to do some basic exercise, normally this is a 40 count of "Side Straddle Hops" or jumping Jacks for you civilians.
Remember the Corps does nothing just for the sake of doing it. The purpose of the "jumping Jacks" it to get your heart rate up and increase your breathing, simulating the bodies reaction to panic in case of a real attack.
So here we are blood pumping and breathing rapidly and skin burning, Nice!
The next step in training here is to make sure that class room instruction paid off and we all know how to put on our gas Masks in an emergency situation, so, we are then instructed to take a deep breath and remove our gas masks, then when instructed to do so, Put our masks back on which is called "Don and Clear" You have 9 seconds to complete this task.
Now when taking off your gas mask, one thing you should never do is open your eyes. remember CS gas effects exposed skin surfaces, so stupid me, as soon as the mask came off, I opened my eyes.
That move lasted for a micro second, and in that microcosm of a moment my eyes immediately caught fire, I can't explain to you the level of discomfort I was in. When the call came to "Don and Clear" our masks, I can't tell you how fast I put my gear on.
Now here is the picture, my heart rate is up, my breathing is way elevated from the jumping jacks, my skin is burning hands neck and bald head, and now my eyes are on fire. But wait !
now in the modern Corps it is at this point the usher all the recruits out of the door gas masks on and everyone is happy RIGHT . . . NO
In my day, I guess in order to see the true cohesiveness of a unit, the next part of the exercise involves team work because non of us were allowed to leave the room until all of our masks were off and put away in our side pouches both buttons locked as in photo above.
As I put my mask away and clipped both buttons, I was beginning to become uncomfortable, I suddenly realized that I was running out of air in my lungs, I needed to breathe. With my eyes closed i could hear the sound of controlled chaos in the room, pouches were being filled people were coughing and there was erratic movement. I on the other hand now could no longer hold my breath, I had to breath my lungs were going to imploded. so I let out the useless air I had and I took the deepest breath you could possibly imagine, only to my horror, what I took back into my lungs , was not air, it was 85% CS gas, I immediately expelled it, but wouldn't you now, guess what, I still needed air, so another load of CS gas went back into my lungs. Somewhere between the expulsion of my second breath and my inhale, we started to exit the room, but we didn't get out before I took that 3rd gigantic breath of CS gas.
I was that guy you see in the Gas Chamber videos that comes out and immediately blows breakfast all over the floor. yeah that was me, but I have to tell you that first breath of free and clear air was amazing
Below is a video of how they are doing it in todays Corps 2013, this video is of the same Company and Battalion I was in at Parris Island almost 34 years earlier