The theme of the International Day of the Preservation of theOzone Layer-2014 was Ozone Layer Protection: The Mission Goes On. 16th September was designated by the United Nations General Assembly as the International Day for the Preservation of the Ozone Layer. This designation had been made on 19th December, 2000, in commemoration of the date, in 1987, on which nations signed the Montreal Protocol on Substances that Deplete the Ozone Layer.