Learn about EPA's efforts to address ozone layer depletion through international treaties and initiatives. This page summarizes the history of international cooperation on the protection of the ozone layer, including: the Vienna Convention; the Montreal Protocol.An international agreement known as the Montreal Protocol on Substances That Deplete the Ozone Layer was reached in 1987. The Montreal Protocol is an international agreement made in 1987. It was designed to stop the production and import of ozone depleting substances. The Montreal Protocol in 1988. This agreement foresees the phasing out of ozone- depleting substances and has now largely been implemented, although the effects. It can be used as a replacement for several compounds with higher global warming potential.