A chemical warfare agent is a chemical substance excluding riot control agents, herbicides, smoke, and flame, used in military operations to kill, seriously injure, or incapacitate though its physiological effects. Chemical warfare agents include blood, nerve, blister, choking, and incapacitating agents. The general population limit is the average concentration below which the general population, including children and the elderly, could remain indefinitely with no effects. Intelligence related to military efforts includes information at the strategic, operational, and tactical levels. Mustard agent can penetrate skin and many materials.
Mustard agents are very persistent under cold and temperate conditions.