A noxious gas used for riot control, causing irritation of the eyes and respiratory tract. Symptoms usually subside within 20 minutes but, if they persist, the victim should be removed to a well-ventilated area, contaminated clothing removed, the affected skin washed with soap and water and the eyes irrigated with water or physiological saline. (CONTACT LENSES should be removed and washed, if hard; discarded, if soft.) If respiratory complications develop, the victim should be admitted to hospital.