Another solution would be to buy a window fan. Put it in the window blowing out and have them put it in and turn it on when they smoke. This would exhaust the smoke to the outside instead of lingering in the room.
Do not allow smoking inside the home, otherwise you will all be breathing the residue no matter what you try to avoid it. On top of that, the nicotine and other chemicals will attach themselves to the ceiling and the walls making eventual clean up a living hell. Also, cig butts thrown all over the sidewalk and front lawn will be frowned upon by the landlord and you may be evicted. Smoking has gone out of style, extremely dangerous in the long run. I personally have had several friends and relatives die from this habit, just lost a cousin to COPD and have another friend dying from it right now. If this dude does not change his smoking habits, you should move out.
Smoking is truly a foolish habit. I agree with Paladin and Clayton. But I work on a cardiovascular unit in a hospital and smoking constricts blood vessels thereby causing heart damage which requires open heart surgery. But it also causes circulation problems to the legs so we start by amputating toes, then feet, then eventually amputating legs. This is a hard fact of life not often seen by the public.
It is your right to breath unpolluted air within your own home. In the past I have told smokers that if they insist on polluting my air with their smoke, then that gives me license to fart as much as I want in their presence and they can breath in my nasty fumes. Certainly that is rude for me to say such a thing, but it is also rude and deadly for people to smoke around non-smokers as if it is their right to damage your health.
I work on a cardiovascular unit in a hospital and smoking constricts blood vessels thereby causing heart damage.
that crap will get everywhere no matter what you do
(smoking should be a deal breaker when looking for a roommate)
Can I close off his vent in that one room? I plan to buy him a window unit and just use that when he's home. Will this do anything that might cause the rest of the house to lose some of the air conditioning effectiveness?