Mom smokes

Noel
Hey everyone! I know I'm super ahead of the game, but I've been thinking a lot about after the babies come. 
My mom smokes (not around us) and I've been reading about how harmful second hand smoke can be for newborns (especially since I'm having twins, I'm worried about them being premies). 
In yall's opinion, what are reasonable things to ask my mom to do? Hubby and I have pretty much decided that if she comes over , smokes outside and comes back in, she's not holding babies. I've also been wondering about asking her to shower before coming over or at least changing clothes. 
Thoughts??