Answer:
1) The ozone layer filters out dangerous ultraviolet radiation from the sun that can cause skin cancer and damage many life forms. ... They had begun creating a dramatic “hole” in the ozone layer at the end of each austral winter. The ensuing panic resulted in the signing of the Montreal Protocol on September 16, 1987.
2) not sure actually but you can say that because of the corona virus it is actually helping to the environment that we can see clear sky. and it is also helping to the world pollution. the word total pollution is decreasing.
3) Ozone depletion over the Antarctic occurs because: Special atmospheric and chemical conditions exist there and nowhere else on the globe. The very low winter temperatures in the Antarctic stratosphere cause polar stratospheric clouds (PSCs) to form.