"It was concluded that ozone is not a lung carcinogen in strain A/J mice at those exposure levels. Moreover, this mouse strain appears to be particularly resistant towards chronic ozone toxicity."
It has nothing to do with covering the turntable mat, but as Harry Pearson was quoted and he has no means of explaining what he meant, it may be fair to emphasize a few things. The study may be correct only for those mice and for those exposure levels. It also mentions that the strain of mice may be particularly resistant towards unwanted ozone action. Both of those statements leave the possibility open that Harry Pearson was correct when talking about humans and/or longer exposure.
Interestingly enough, quick search on PubMed does not yield any recent work on ozone and cancer. All we seem to have is one study done twenty years ago in mice that appeared to be particularly resistant to begin with.
I suggest that "carcinogenic tendency of ozone" debate in the thread about covering the turntable mat ends with no clear winner.
