nonvesicants

Nonvesicants are chemical agents that do not cause vesication (blistering) on the skin, in contrast to vesicants such as sulfur mustard. They encompass several classes of irritant agents, including lacrymants (tear gases), irritants, vomiting agents, and choking or asphyxiant gases. The characteristic effects are irritation of the eyes, nose, and throat, coughing, and breathing difficulty. In higher exposures some nonvesicants can cause pulmonary injury, but they do not form lasting skin blisters in the way vesicants do. Exposure risk depends on concentration, duration, and route, with inhalation being the primary pathway for many agents.

Common lacrymants such as CS and CN produce rapid tearing, eye burning, and mucous membrane irritation and are used historically for crowd control. Chlorine gas and other irritants affect the eyes and airways and can provoke coughing and chest tightness. Choking agents like phosgene and chlorine damage the lungs and can cause delayed pulmonary edema. Vomiting agents, including Adamsite, induce nausea and vomiting and can disrupt behavior and coordination.

Nonvesicants have been used in warfare and crowd-control contexts but are regulated under international law. The Chemical Weapons Convention prohibits development, production, stockpiling, and use of chemical agents as weapons; riot-control uses are subject to strict limitations and national law. Protective measures include sealed protective masks with filters appropriate for the agent, effective ventilation, and prompt decontamination and medical care for airway and eye injuries.