Concerns with family smokers & my infant while on vacation

I'm just going to say this,
My grand daughter has "asthma", she uses a rescue inhaler. Her mother and father smoke, heavily. She has been living with me for the past 2 weeks and hasn't had the 1st issue with the asthma nor has she needed the inhaler.
My wife and I don't smoke.
conclusion of "un-scientific study": kids are susceptible to long term cigarette smoke, but re-bound quickly. Adults, not so much.