International Day for the Preservation of the Ozone Layer is observed on September 16 annually. In 1994, the UN General Assembly proclaimed September 16 as the day commemorating the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer. Ozone layer is the sheet of gas which protects the Earth from harmful rays of the sun by absorbing most of the ultraviolet radiation. Watch the video to find out ways to protect the ozone layer from depletion.