Origins of Chlorofluorocarbons and Halons

Monitoring and Management‎ > ‎4. The Atmosphere‎ > ‎

Identify the origins of chlorofluorocarbons (CFCs) and halons in the atmosphere

  • Chlorofluorocarbon (CFC): A haloalkane that contains both fluorine and chlorine atoms, and no hydrogen atoms.
  • Halon: Also referred to as a brominated CFC, a haloalkane that contains bromine, chlorine and/or fluorine atoms, and no hydrogen atoms.
  • CFCs were developed in the 1930s to replace ammonia as refrigerants.
    • CFCs became extensively used as:
    • Refrigerants.
    • Solvents in dry cleaning.
    • Propellants in spray cans.
    • Blowing agents for expanded plastic products.
  • Halons were developed for the extinguishing of electrical fires.
  • Halons became widely used for this purpose, but were never used as extensively as CFCs.
  • Through their various uses, CFCs and halons were released into the atmosphere.
  • CFCs diffuse into the stratosphere because:
    • They are not destroyed by sunlight and oxygen in the troposphere.
    • They are insoluble in water, and are thus not ‘washed out’ of the atmosphere.

Dichlorodifluoroethylene, and example of a CFC