[johnboiles]

That seems incredibly fast for plastic to degrade like that. I wonder if you could have something generating ozone in there.

[alienchow]

I'm not sure either. It's not an air tight bomb shelter and it's used like an average storeroom, storing stuff like winter jackets, suitcases and paint. I do use small amounts of Calcium Chloride based dessicants to keep the room dry.

[mixologic]

Have you checked for Radon?

[mzhaase]

Water based or solvent based paint?

[chneu]

If it's underground at all, check for radon.

[adzm]

My first thought exactly. I know someone who inadvertently melted a ton of stuff with overuse of an ozone generator, similar kind of effect

[da768]

With all these paper reams on the picture, is there any laser printer nearby?