If the ozone layer is made of different gases and such....?

Question

If the ozone layer is made of gases like oxygen and all the rest, how is it that holes have formed in the ozone layer and stayed there, instead of just fusing back together?

Answer 1

The Ozone "Hole" is a bit of a misnomer really, it's actually a thinning of the Ozone Layer, which allows more UV radiation etc. from the sun to penetrate into our lower atmosphere.

The thinning has always been present too, since the nature of gases (as you pointed out) is not to stay in any particular one place and to move about.  It's just that due to the relatively recent accumulation of greenhouse gases the thinning has become more pronounced and the Ozone layer does not deflect the harmful radiation as effectively as it used to.