I live in an industrial loft. My downstairs neighbor is a factory. When they're running, fumes come up through my bathroom into my apartment. It's serious problem.
The guy who lived here before me put in the pipes himself (he left behind the tools, even) and I'm guessing he did a slapdash job of sealing around them. I'd like to find the penetration that the fumes are coming through, make an airtight seal around that pipe, and live in peace and harmony with my downstairs neighbor once more.
Problem step 1: How do I figure out which penetration is leaking fumes? (Some of the penetrations, like the 3 water lines to the faucet, are closed off behind a boxy sink, too.)
Problem step 2: How do I seal it?