I'm going to ask my roommate not to smoke in the house.
Why don't you want them smoking in the house?
I can't stand the smell of it and everything absorbs that smell.
I'm sure you must be frustrated with your roommate. Smoking is a habit that is unpleasant to be around and you have every right to ask your roommate to smoke away from the house. Sit down with him and work out some ground rules about his smoking.
Thanks I appreciate your help and I know that I can help him to realize that it's detrimental and to not smoke in the house.
I agree with you. It's common sense to know not to smoke in someone's home, but if he doesn't understand that then you can help him to understand.