A series of chemicals traditionally used in fire supression systems. The first of these is carbon tetrachloride, used in the early 1900s. Sadly, the combustion by-product of carbon tetrachloride, or Halon 104, is lethal to humans. Halon 1211 and 1301 were developed to relieve the poisonous aspect of this effective fire supression agent. However, since Halon displaces some air when released, sealed environments which use Halon fire supression systems, namely computer server rooms, must contain portable air supplies to allow for safe evacuation.