The depletion of the ozone layer is primarily caused by human-produced chemicals known as Ozone- Depleting Substances (ODS), such as Chlorofluorocarbons (CFCs) and Halons. CFCs were widely used as propellants in aerosol spray cans, refrigerants, and in foam blowing. While 'Aerosol' itself is a physical state (particles suspended in gas), its use as propellants for products containing ODS like CFCs made aerosols a significant contributor to ozone depletion before these substances were phased out.