A lack of sunlight hitting the ozone layer. This is the reason that the thinning occurs only at the two poles and why it is larger in the Antarctic Ozone requires large amounts of energy and without the sunlight it reverts to oxygen. There may be some element of human interference with this natural event.
CFC's have been discovered in trace amounts in the layer and they may also contribute to some extent. There is no thinning in any areas outside of these non lit areas. The equator, for example, remains the same as it has been for years.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.