Sarin is a volatile liquid used as a nerve gas. Its vapor is colorless and odorless. Sarin acts by interfering with a chemical which transmits impulses from one nerve cell to the next. A gas mask provides adequate protection from the vapor, but the liquid form can also be absorbed through the skin. Sarin was originally developed by the Nazis during World War II.
On March 20, 1995, the Tokyo subway sarin gas attack occurred killing nearly a dozen people and injured approximately five-thousand others. The sarin was placed in six devices placed on different trains to deliver the gas to a Tokyo government center where the national police headquarters all at the same approximate time. They were disguised in devices as a soft drink can, a briefcase, white plastic bag and a gas can wrapped in newspaper. Very soon after the gas was released, reports of injured people from fifteen underground stations came in stating they were exposed to sarin on the trains or on the platform. People immediately experienced breathing difficulties and muscle weakness. Many victims even lost consciousness. Emergency first aid stations and personnel were immediately set up and began getting treatment to the victims of the attack. Victims were sent to hospitals via ambulance for treatment with mild symptoms. When the victims arrived for treatment of sarin, the hospitals didnt have the sarin antidote but knew that it was an organophosphate. They knew how to treat organophosphate pesticide poisoning and used the same treatment for the sarin. Emergency personnel and police who responded to the accident site also developed symptoms as well as hospital staff.
The group most likely responsible for the attack was AUM SHINRIKYO, a religious cult. This cult had a sarin gas leak at their compound at Matsumoto in June of 1994 in which seven people died and injured 200 victims. The cult played off the incident by saying the chemical precursors were being used for industrial purposes and no one in their organization had the knowledge how to make sarin gas. They also said the whole matter was conspired by the United States.