A few months ago, I moved into a larger apartment in the same building that I lived in previously. The building is well over 100 years old, all brick, but with some water damage (especially after this past winter's heavy snows).

In the previous apartment, I've never had an issue with food (especially bread) molding. Now, mold is a scourge.

I like to bake bread, and the last batch I made had mold on it within two days, despite being stored in an air-tight zip-lock plastic bag. Even bread that I put in the fridge seems to mold over quickly, and not to mention fruits/vegetable that are left on counters.

What's going on?

I keep my kitchen nicely aerated, there is no visible mold on any walls or anything like that, and neither my GF nor I have had any respiratory/allergy issue that are tell-tales of a mold infestation.

Is there anything I can do besides vacuum-sealing everything?