Tear Gas, any of various chemicals that produce severe eye irritation, usually resulting in a blinding flow of tears and often also minor skin and respiratory irritations, such as itching and coughing. Tear gas is used primarily by police and troops for mob control. The effects of tear gas are temporary and recovery is complete, usually within a few minutes. A gas mask will protect the wearer against tear gas.

Chemical compounds used as tear gases are called lacrimators. Lacrimators, which exist most often in liquid or solid form, are usually dispersed into the air as gases by being exploded from grenades, bombs, or shells. (The liquid or solid lacrimators are vaporized by the heat of the explosion.) Liquid lacrimators, as well as solid lacrimators dissolved in liquids, are sometimes sprayed into the air. The most widely used lacrimator is chloroacetophenone (CN); others include ochlorobenzalmalononitrile (CS) and chloropicrin (PS). Tear gases were widely used during World War I. Tear gases mixed with vomiting gases were used in the Vietnamese War.