Ozone is created in the spark gap of electric motors (and welding, I believe). And, yes, it degrades tire rubber. I'd be surprised if running a central vac for 10 minutes a week would be enough, though.
Did you check the tire-manufacture date codes to see if the tires were built before 2005? If it was a 2003 tire put on a new bike in 2004, it might just be getting old.
Also, if the tires have been through a lot of heat cycles, that might contribute to premature cracking.