Just read "What property allows ozone to absorb uv light" together with excellent answers. The driver here, i.e. the source of both the short and long wave UV, is of course sunlight. This is notably absent for six months of the year at the poles, so can anyone explain why one would "not" expect holes in the layer there?
Also, is it true that there have never been measurements of the layer that did "not" reveal holes at the poles?