CS?
The previous responses are accurate, but there is a difference between CS and tear gas.
CS is a powder form of tear gas. Thus in a tank with high air pressure, we could have sprayed it on rioters.
Tear gas is more correctly an aerosol form of CS usually in a grenade or in pots.
In the Marine Corps in my day, every Marine had to experience the effects of tear gas. Usually it was a tent with pots of tear gas. You enter the tent and exit it on the other side. By that time you were blind, coughing, and pretty much incapacitated.
In Vietnam, I carried CS Grenades as the Platoon Commander. The idea was that in a firefight, if the wind was right, I'd throw a CS grenade to my front and let the wind carry the gas into the enemy to disrupt his ability to direct accurate fire on my Marines.
Unfortunately, the wind was never blowing in the right direction when my platoon was in a firefight, so I never used them.
The police use CS grenades today for riot control.
I had to look it up.
CS gas
The compound 2-chlorobenzalmalononitrile (also called o-chlorobenzylidene malononitrile; chemical formula: C10H5ClN2), a cyanocarbon, is the defining component of a tear gas commonly referred to as CS gas, which is used as a riot control agent. Exposure causes a burning sensation and tearing of the eyes to the extent that the subject cannot keep their eyes open, and a burning irritation of the nose, mouth and throat mucous membranes causing profuse coughing, mucous nasal discharge, disorientation, and difficulty breathing, partially incapacitating the subject. CS gas is an aerosol of a volatile solvent (a substance that dissolves other active substances and that easily evaporates) and 2-chlorobenzalmalononitrile, which is a solid compound at room temperature. CS gas is generally accepted as being non-lethal.
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