In the 1990s, most uses of Freon chlorofluorocarbons (CFCs) were phased out due to the negative effects that CFCs have on the Earth's ozone layer. DuPont began to phase out its production of Freon CFCs in the 1980s after federal regulatory agencies banned their use.[2] The interim replacements for CFCs are hydrochlorofluorocarbons (HCFCs), which contain chlorine that depletes stratospheric ozone, but to a much lesser extent than CFCs.[3] Ultimately, hydrofluorocarbons (HFCs) will replace HCFCs with essentially no ozone destruction, yet they are classed as greenhouse gases. DuPont began producing hydrofluorocarbons as alternatives to Freon in the 1980s. These included Suva refrigerants and Dymel propellants.[4] Any of these gases that are used as refrigerants are designated by an "R-" number and colloquially known as "Freon", whether they are made by DuPont or another supplier.