In 1994, the UN General Assembly proclaimed 16 September the International Day for the Preservation of the Ozone Layer, commemorating the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer (resolution 49/114).
States were invited to devote the Day to promote activities in accordance with the objectives of the Protocol and its amendments. The ozone layer, a fragile shield of gas, protects the Earth from the harmful portion of the rays of the sun, thus helping preserve life on the planet.
Hashtag: #ozoneday
http://www.un.org/en/events/ozoneday/