Gases covered under the 1987 Montreal Protocol and used for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol propellants. Since they are not destroyed in the lower atmosphere, CFCs drift into the upper atmosphere where, given suitable conditions, they break down ozone. Other compounds are replacing these gases: hydro chlorofluorocarbons, an interim replacement for CFCs that are also covered under the Montreal Protocol, and hydro fluorocarbons, which are covered under the Kyoto Protocol. All these substances are also greenhouse gases.