Holy crap. That is no joke. Exactly why I take it upon my self to check out everything. I learned the lesson hard as well. Was living in an apartment complex 5 years ago. Show had a leak behind the wall, maintenance repaired the wall and the leak. Never thought to look on the other side of the wall, which was a storage closet I barely ever used.

Turned out that wall had absorbed water, turned into mold and just sat there. It was there for nearly a year. My desk was 12 feet from that closet and I work from home. I was moving out, which is why I discovered it, but I swear I have not been the same since then. Never ever used to get sick. Now I seem to come down with something atleast once a year.