How can I close up the divided wall?

The room Im in is divided in two, just by a wall divider. So the top of the divider doesn’t reach the ceiling; it has about a 17inch gap between the ceiling, and the top of the divider. Im on one end, and another family member is in the other room.

My issue is that he is a VERY heavy smoker (ie, he lights up as soon as the last one is done). I myself, am not a smoker, and so anything in my room starts to smell like nicotine, because the divider isn’t a full wall. This has been so discouraging that I’ve had to bunk in the other room, and even put all of my other cloths with someone else in my house, because I can’t stand the smell. I can’t spend time in there, or anything, because it’s so bad when I walk in, let alone sit in there.

I need a better solution of how I could possibly close up that gap, or do SOMETHING, so that room is liveable again. And please don’t say to tell him to stop smoking, because he is an old stubborn man that is stuck on his own arrogant ways. I just need a solution so I can live in my room again.

Any help would be VERY appreciated.

Thanks guys..