The chloro and fluoro carbons, when going into the air, tend to migrate towards the poles, where they will remain frozen during the course of arctic and antarctic winter, once the sun hits the poles, large clouds of frozen chemical undergo the reaction in the write-up above producing chlorine in a gaseous form. (which is actually Cl2(g). When hit with light, chlorine molecules undergo a chain reaction activated by light, which involes chlorine radicals, (an atom with an uncoupled electron in it's outer shell - ususally denoted by the element name with a suprescripted dot), radicals are VERY reactive, and are attracted to the conjugated bonds of the ozone, breaking it up.

The danger is: these compounds get released in large enough amounts at once because they are able to accumilate in its frozen form over half a year of winter

Also, ozone takes a LOT of energy to regenerate and it does not happen nearly at same rate as it si destroyed. Curiously enough, when you read that the hole has gotten smaller over the last decade, don't be mislead. Ozone, out atmosphere in general, is made up of gases, and naturaly over the period of time, the will diffuse from higher concentration to lower concentration, thus, the ozone hole, so as the hole has gotten smaller, the overall atmosphere has gotten thiner over this century.