Sarin is a chemical weapon that is classified as a nerve agent, meaning that it works by attacking the function of the nervous system. It is extremely dangerous; an amount which would fit on a pinhead is enough to kill a healthy, full-grown adult. Like other chemical weapons, sarin is banned under the Chemical Weapons Convention of 1993, which means that signatories should not be producing, stockpiling, researching, selling, or using this agent. However, it is possible for terrorist organizations to manufacture it, as illustrated in 1994 during the Aum Shinrikyo attack on the Tokyo subway system.
This chemical was developed in the 1930s by the Germans, who initially planned on using it as a pesticide. German researchers knew sarin as GB, classifying it among the G-series of chemical weapons, and the United Nations prefers to use that term. The chemical formula of sarin is C4H10FO2P, making it a member of the phosphinates. It interferes with the production and transmission of the enzyme cholinesterase, which normally allows muscles to relax after they have been contracted.
Sarin is a colorless, odorless liquid that evaporates at room temperature, making it ideal for aerosolized dispersal. However, it also breaks down very quickly, having a short life of only a few weeks; most facilities which produce and work with it, therefore, keep the constituent chemicals around, rather than stocks of sarin itself. To destroy the chemical, a strong alkali is used to break it down.
Exposure to sarin results in a constriction of the pupils, as they are unable to relax, along with a runny nose, shortness of breath, and nausea. These symptoms can appear within moments of exposure, followed by a complete loss of muscle control and, ultimately, death. People who are exposed to it can be treated with an antidote if they are promptly identified. Victims of the Tokyo gas attack often described a sense of growing darkness when discussing their exposure, as well as a general lack of coordination and an inability to think clearly.
Because sarin is so dangerous, ordinary civilians are unlikely to be exposed to it. However, exposure is not impossible, especially for people who live in areas which could be considered potential terrorist targets. The US Centers for Disease Control recommendations for exposure include moving promptly to an area with fresh air, stripping to remove contaminated clothing and bagging said clothing, and quickly washing with soap and water to remove the chemical from the skin. Prompt hospitalization is needed for any hope of recovery.