Could smelling vape harm baby?

Get him in a routine now before the baby comes. Make him go outside when he needs a smoke. I think he should quit as popcorn lung is not something to take lightly.If he continues to smoke inside it increases the risk to SIDS.

Ask him to do it somewhere else like out of a window. My partner does it on the balcony with the door closed

Well itis less harmful than actual smoke with tar in it. But it would still be better if he vaped somewhere else. It still probably might not hurt but you never know, I think there are not enough studies about it.

Less harmful is vaping compared to cigarettes BUT they havent been around long enough for extensive research into the health impacts so would avoid x