Learn about EPA's efforts to address ozone layer depletion through international treaties and initiatives. For the purposes of this Protocol: 1."Convention" means the Vienna Convention for the Protection of the. Sound science and targeted regulations have greatly reduced ozone concentrations in Texas cities and across the nation. The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer The world's first environmental cleanup agreementor, more formal, the Montreal Protocol on Substances that Deplete the Ozone. In the early 1980s, scientists began to realize that CFCs were creating a thin spot—a hole—in the ozone layer over Antarctica every spring. In the 1980s, scientists noticed that the ozone layer over Antarctica was thinning.