A compound obtained by replacing the hydrogen atoms of a hydrocarbon by bromine along with other halogen atoms (see halocarbons), for instance halon 1211 is bromochlorodifluoromethane (CF2BrCl) and halon 1301 is bromotrifluoromethane (CF3Br). Halons are very stable and unreactive and are widely used in fire extinguishers. There is concern that they are being broken down in the atmosphere to bromine, which reacts with ozone, leading to depletion of ozone layer, and their use is being curtailed. Although more chlorofluorocarbons are present in the atmosphere, halons are between three and ten times more destructive of ozone.
Subjects: Meteorology and Climatology.