Ortho-chlorobenzylidene malononitrile, commonly known as CS gas, is a chemical compound used primarily as a riot control agent. It is a colorless to pale yellow solid that can be dispersed as an aerosol. CS gas irritates the eyes, skin, and respiratory system, causing temporary incapacitation. This compound is often utilized by law enforcement and military personnel for crowd control and self-defense. While effective in dispersing crowds, its use is controversial due to potential health risks and ethical concerns regarding its deployment in various situations.