We all knew this day would come, but none of us knew what to expect. The small cinder block building was not at all intimidating, yet we were anxious. We were ordered to take off our BDU tops, line up in a single file line, and don our gas masks. Six at a time we were led in...

More than just a big word, the compound o-chlorobenzylidenemalononitrile (C10H5ClN2), otherwise known as CS gas or simply tear gas, is a non-lethal lachrymator commonly used as a riot control agent. Interestingly enough, CS gas is outlawed by the Chemical Weapons Convention which amends the Geneva Convention - so it is illegal to use the compound against your enemies in war, but is perfectly lawful to use on unruly civilians.

Check the seal. Breathe. In, out, in out. It won't be that bad.

It was our turn, and me and five other members of my platoon were led in. There stood one of our drill sergeants in a very hazy room standing behind a small stove - he in his gas mask, we in ours. We were ordered to stand at the position of attention - and then we just stood there for about a minute. One soldier in our group started to rub his arms.

"Dammit private! Who told you that you could move? You're just going to make it worse."

We were then ordered to hold our breath, close our eyes, and break the seal on our mask. After checking that we had all done this we were told to re-sealed our masks. Apparently one of the guys didn't reseal properly and he started choking.

"Alright, take off those masks!"

CS was first discovered by an American scientist in 1928. For many years, chloroacetophenone (CN gas) was the most common agent used by civil and military authorities, and was the active ingredient in mace. Being dissatisfied with the potency of CN, CS was further studied in the 1950s by the Chemical Defense Experimental Establishment in Porton, England. Often delivered through grenades or canisters, it is a white crystalline substance that when burned creates a smoke or fog of particles in the air with high concentrations approximately 6 to 9 meters in diameter. Alternately, it can be sprayed from an aerosol can or even dusted on the ground where it can remain active for weeks at a time. Even in small doses, these particles cause immediate tearing of the eyes, conjunctivitis, blepharospasm, irritation and burning of the skin, eyes, and mucous membranes, and has also been known to cause vomiting and prostration. While the symptoms are extremely uncomfortable, recovery is relatively fast - usually within 15-30 minutes after leaving the area of dispersal. It is referred to as a harassing agent because there do not seem to be any long term or serious effects of exposure1, however there are numerous cases where people have been injured by the fragments of an exploding canister. While studies have shown that long term or high concentration exposures can cause serious health problems, neither of these conditions occur when the agent is used for riot control. In addition, it is a natural response for victims to flee the area, so exposure is further limited.

We all took off our masks except that guy who was rubbing his arms. He was having some trouble.

"What is your fucking problem, private? The longer you take, the worse it is for your buddies. Are you a buddy fucker, private?"

"No sergeant!"

I was taking shallow breaths while all this was going on. It didn't seem too bad. In, out, in, out. Then suddenly I felt a burning sensation in my lungs. My skin started burning, and my eyes started to sting. Soon it was hard to see or breathe. I heard some sounds of astonishment from the other guys as they started to feel the effects as well. Soon we were all coughing. We remained standing there for an unknown amount of time. Finally we heard the most beautiful words we had heard in weeks:

"Right, face! Forward, march! Go on! Get out of here you pussies!"

Treatment for exposure to CS gas is relatively simple.

  • Get out of the area of exposure.
  • Remove outer clothing. Cutting them off will reduce the length of effect because you will not be rubbing the affected clothing over your skin.
  • Do not touch your skin or eyes.
  • Try to take deep breaths.
  • Washing the skin and flushing the eyes with water tends to create an increased (though shortly lived) burning sensation; however it is shown that this does decrease the total length of effect of symptoms.
As we left the building with mucus pouring out of our nose and mouth, we were told to keep our arms outstretched and not to touch our face. It was several minutes before I was able to keep my eyes open for more than a second at a time. Since the line to enter the gas chamber had been very long, and I was near the back, there were several soldiers who had already recovered from the experience and were laughing as each new group came out. Even through the discomfort, I could hear people coming out as well - some of them vomiting - all of them coughing horribly. As I slowly regained my vision, I could see that we were all a terrible mess. Red eyes, red skin, slimy mucus all over people's clothes, but in the end, we all made it.

Exposure to CS gas is a common experience for soldiers in the US Army and US Marines. It is supposed to teach you the value of your gas mask, that there is no need to panic, and that you can deal with uncomfortable situations. Depending on your Military Occupational Specialty, you might receive regular doses of CS simply to test your responses to the situation, or for other training purposes. Believe it or not, you can actually get used to it. By the end of basic training and AIT I actually enjoyed the smell of the stuff in small doses (though I doubt I would any more). I'll never forget my first experience with it though.

Additional Information


1 As with nearly anything, there are exceptions. Some individuals have reported serious respiratory or dermal problems, though usually exacerbated by a pre-existing condition.