Smoking in laws

So my in laws are some heavy smokers and in my MIL eyes she doesn’t seen anything wrong with smoke in the same room as a baby. I’ve already told her that won’t happen but how do I nicely tell her she needs to change her clothes and wash her hands before handling our new born? I’ve read so much on third hand smoking and SIDS and i don’t want to be aggressive but.... bitch don’t touch my baby lol