"As most of the industry is in the northern hemisphere, how come the ozone hole that we have been worrying about for so long, is over the South Pole?"

In laymans terms, the atmosphere spreads the agents that deplete the ozone layer about globe fairly evenly. They remain active far longer in cold areas. The Antartic is far colder than the Artic, so the ozone hole is bigger there.

And if you want a preview, go to New Zealand. Clean air, and a thin ozone layer mean factor 30 sunscreen and hats as standard for everyone.

PM if you want more details on atmospheric chemistry. You don't.