We have managed to completely keep baby away from smokers all together at six months-- coincidentally, the same family who wouldn't get TDAP over "health concerns" about vaccines also knowingly inhale 2 packs of the cancer sticks a day. They are coming to meet her next month now that we have had our six month vaccinations. (Third hand smoke wasn't the hill I was willing to die on, vaccines were.) I feel a little bit better knowing that 90% of SIDS deaths happen in the first four months of life. At seven months our odds of our are dramatically lower. I will still be enforcing handwashing and a fresh shirt, but not a shower or strict no smoking on their trip ban based on the age of my child. If they refuse TDAP maybe it will also become less of an issue for you until baby is out of the highest danger of SIDS as well.