Blister agents

Blister agents (also known as vesicants) include three types: sulfur mustards, nitrogen mustards and lewisite. The two types of mustard gases and lewisite cause blisters on the skin and cause damage to the respiratory system. The effects of mustard gas will not be evident immediately: although a victim may experience some minor symptoms immediately after exposure, it will take 3 to 12 hours for the poisoning to have a serious  effect. The LCt50 (lethal concentration and time in which the substance is lethal for 50 percent of the contaminated group measured in mg.min/m3) for inhalation of sulphur or nitrogen-mustard is 1,500 while the LCt50 of lewisite is 1,200.