Manufactured halocarbon chemicals used in products like refrigerants, foam blowing agents, and propellants are the main cause of ozone layer depletion. These ozone depleting substances include chlorofluorocarbons, carbon tetrachloride, methyl bromide, and hydrochlorofluorocarbons. An international agreement in 1987 set limits on CFC production, and reducing emissions of ozone depleting chemicals has helped decrease the size of the ozone hole over Antarctica in recent years.