Halons, a kind of ozone-depleting substance (ODS), were essentially and widely used in

Halons were used chiefly in fire extinguishers, where they smother flames very effectively.

Refrigerators relied mainly on chlorofluorocarbons, not halons.

Air conditioners also used chlorofluorocarbons and later hydrofluorocarbons.

Aerosol spray propellants used chlorofluorocarbons rather than halons.

The bromine-bearing halons found their main role in fire suppression.

Halons deplete ozone strongly and are phased out under the Montreal Protocol.