Cfc's or chlorofluorocarbons while once seen as chemically inert (as they did not react with many things that the scientists at the time could have immediately noticed) actually react with Ozone in the ozone layer causing it to deplete leading to scientists and people banning the use of cfc's in hairsprays and other products and now people use HCF's or Hydrochloroflorocarbons which does not have the same effect! ^^; I hope this helps