halon

Organic chemical compound containing one or two carbon atoms, together with bromine and other halogens. The most commonly used are halon 1211 (bromochlorodifluoromethane) and halon 1301 (bromotrifluoromethane). The halons are gases and were once widely used in fire extinguishers. As destroyers of the ozone layer, they are up to ten times more effective than chlorofluorocarbons (CFCs), to which they are chemically related.

Levels in the atmosphere are still increasing, mainly through the testing of fire-fighting equipment. The use of halons in the production of fire extinguishers was banned in 1994.