International Day for the Preservation of the Ozone Layer 2022: Theme, History and Significance of World Ozone DaySeptember 16th marks the International Day for the Preservation of the Ozone Layer. In 1987, representatives from 24 countries met in Canada’s Montreal to discuss the alarming situation of depleting the Ozone layer. The countries agreed on the Montreal Protocol on Substances that Deplete the Ozone Layer, calling for the world to get rid of the substances that cause Ozone depletion.