Identify a type of chemical agent sometimes used in nonlethal contexts.

CS gas, commonly known as tear gas, is a type of chemical agent that is frequently employed in nonlethal contexts. Its primary function is to disperse crowds, incapacitate individuals temporarily, and provide law enforcement personnel with a means to manage various scenarios without resorting to lethal force. CS gas works by irritating the mucous membranes in the eyes, nose, and throat, leading to tearing, coughing, and difficulty in breathing, which serves to disorient and incapacitate a person without causing permanent harm.

In comparison, options like chlorinated hydrocarbons and mustard gas are primarily associated with harmful, often lethal, chemical warfare and are not suitable for nonlethal applications. Pepper spray, while also a nonlethal option, does not share the same widespread usage in crowd-control scenarios as CS gas. This distinction highlights the specific role of CS gas within the realm of nonlethal chemical agents.