September 16 - International Day for the Preservation of the Ozone Layer

September 16 was designated by the United Nations General Assembly as the International Day for the Preservation of the Ozone Layer.

This designation was made on December 19 1994, in commemoration of the date, in 1987, on which nations signed the Montreal Protocol on Substances that Deplete the Ozone Layer.
Links:
Wikipedia
United Nations

September 15 - International Day of Democracy

Throughout history, democracies have flourished, been threatened or dismantled, and re-emerged in societies all over the world. The United Nations acknowledged the resilience and universality of the principles of democracy by declaring 15 September the International Day of Democracy.
Links:
1.United Nations
2.Wikipedia
3.Global democracy day