CFCs (Chlorofluorocarbons) were widely used as refrigerants in refrigerators and air conditioning systems, and as propellants in aerosol sprays. However, they were never used in fire extinguishers - fire extinguishers typically use carbon dioxide, foam, dry chemical powders, or halon (before its phase-out). CFCs were phased out globally under the Montreal Protocol due to their ozone-depleting properties.