Roommate smokes cigarettes indoors, would like advice on how to deal with the smell.

To keep private information private, what I will say is that I share a hallway with a roommate who smokes in his room, whether it be cigarettes or weed. As I am currently unable to stop his behavior while also being unable to change my living situation, I'm stuck with this.

Is there a way I could deal with the smell? Candles don't even help, nor do those wall plugins.