CS is a tear gas, developed in (I believe) the late 1950s to replace the somewhat less potent CN. Having been teargassed I can assure you that it's unpleasant but that I'd much rather be gassed than shot or beaten or stabbed.

Sprays have their drawbacks -- spray into the wind and it comes back into your own face. Face into the wind and let it blow the gas clear if you are teargassed; glasses and a bandana around the mouth will also provide some protection.

Now, if you want to use some REAL nasty gases, try vomiting gas...that even penetrates some type of gas masks. Or a mix of CS and vomiting gas....