Is hardwood floor varnish toxic to breath?
It is not healthy to breath the fumes of any finish, although shellac and water-based finishes are the least problematic. You shouldn’t be in a harmful situation since the varnish is being used down the hall, but they worker should still ensure there is adequate ventilation to ensure everyone is breathing relatively clean air. If you can smell it, it means there are fumes and the landlord should ensure you (especially with a small child) are provided with temporary ventilation, fans, etc until the varnish cures.