[Arete314159]

If you're feeling sick in a building, you can't leave out mentioning mold. Mold will really destroy you.

Also ozone machines, when used properly and safely (no occupants), can sometimes help to speed up the offgassing process. If you're interested in doing this, please read up on it so you don't do it wrong or dangerously. It can also in some cases cause new, worse VOC's to form, so...user beware.