Chemical odor from the exterior wall

If I paid proper attention in chemistry (have of course also done a quick Google search) this falls into the group of aromatic hydrocarbons. But aromatic is not a good thing in this context. It vaporizes and in the worst case knocks you out. MEA should be completely removed.

Hollow chamber bricks don't mean you can put a soda can inside them. A can with solvent or something similar must have been spilled inside there, probably not intentionally, it has seeped into the bricks. Something like that.