There is new research suggesting third-
hand smoke (particles on clothing, furniture, etc.) is carcinogenic, not just first- and devond-hand. Any time you can smell it, you and your kids are exposed to cancer-causing agents. I have no idea what the law says, but you might be able to bring this up with your landlord (research in hand) or even CPS. Of course, it may be that nothing comes if it, in which case you will have to live with it, or find a different living situation.