International Day for the preservation of the Ozone layer is observed on.

Explanation

September 16. The ozone layer (found in the stratosphere) is a thin part of Earth's atmosphere that absorbs almost all of the sun's harmful ultraviolet light. 18 September - World Bamboo Day, 21 September - International Day of Peace (UN), 26 September - World Environmental Health Day, 10 September - World Suicide Prevention Day (WSPD).