Explanation

Chlorofluorocarbons used in refrigerants, aerosols and solvents drift to the stratosphere, where ultraviolet radiation releases chlorine atoms that catalytically destroy ozone, with one chlorine atom destroying tens of thousands of ozone molecules. This caused the Antarctic ozone hole and led to the CFC phase-out under the Montreal Protocol (1987). Carbon monoxide, methane and pesticides were not responsible for the last century's ozone depletion. Hence chlorofluorocarbons.