Back in the 80's, I had a job as a bench tech at a repair shop, and we had a customer who would be bringing her VCRs, tape decks, answering machines in all the time for mechanical issues like broken belts, dried out pinch rollers, cracked idler tires, etc. LOTS of seriously dried and deteriorated rubber. Turns out she was a BIG believer in those negative ion generators, which apparently were pumping out a non-trivial amount of ozone.
She refused to believe that they were the cause of the problem, until we gave her an extra brand new belt, and had her drape it over one of the units as a test. It crumbled to dust when she went to check it a month later. I have to wonder what all that ozone was doing to her lungs...