E- Cigarettes

Okay, so... I am feeling so frustrated right now. My husband smokes his Vape non-stop. I swear he breathes it in more than air. At first I didn't have a problem with it because it started out as a casual thing but now I just feel like he's addicted and its getting worse. I know some say that it's safer or even better than smoking cigarettes but honestly I feel like that's wrong. I just feel like there hasn't been enough long term research done to really show what the habitual smoking of e-cigs can really do to the human body.  I have tried talking to him about it and just like anyone who's addicted he said that he'll stop eventually. He's just so young and healthy and I would hate to see this bad habit hurt him. What should I do? What do you guys think?