World Ozone Day, observed every year on September 16, is also known as the International Day for the Preservation of the Ozone Layer. The date was designated by the United Nations General Assembly in 1994, commemorating the date in 1987 when nations signed the Montreal Protocol on Substances that Deplete the Ozone Layer. The need to declare an action to preserve the ozone layer came as a result of the outset of its depletion. In 2017, 30 years after the Montreal Protocol, the closure of the hole in the ozone layer was observed and the effects of this have been projected to last up to 100 years.
