I made the mistake of using my ozone box with a mask inside - destroyed the elastic. (I put rubber bands on.)
I used to use my UVC light on masks, but the inventor of the 3M N95 masks said that is bad as the UVC light breaks down the synthetic poly-something inner filter.
He said either heat in your oven, suspended by a wood clothespin (170 at 30 minutes), or better yet - just hang it at room temperature for 3 to 4 days. I have a few masks and don’t go out more than once every three days so that is what I do now.
I try to go out only once a week, but taking care of others, and it seems there is always an extra run to the pharmacy or something. At least nowadays they know better than to ask me to “stop by the store and pick me up some donuts on the way over”.
That's a good point about how destructive O3 can be to rubber or plastic. Decades ago, I had a brief engineering internship in a testing lab, where I tested plastic and rubber parts for (among other things) ozone resistance. After a couple of weeks in the O3 box, most products would still look normal; but, they would crumble into dust when picked up -- just like the mummy in a bad horror movie.
I'm just trying to make the best of what I have (don't let perfection be the enemy of good enough). So far, I have experienced no obvious problems with the masks I use -- but, I'm half expecting my plastic box to crumble any day now.
FWIW, here's a photo of an O3 box that Magna International makes. I found out about it a few weeks after I Macgyvered my box. Magna is applying to the FDA for certification to use their box for sterilizing PPE for reuse. If they get certified, I'll continue to use my box; if not I won't use if for masks. Meanwhile, I should probably try the heat method too.
