My Mother In Law Smokes, How Can I Keep The Cigarette Smoke Out Of My Room? Does An Air Purifier Work?

we both live in an apartment. my bf and our 15 mo old baby live in a room and his mom in another. she smokes alot in her room out the window with a fan, but it still lingers. can i buy an air purifier or sumtin? we've asked her to consider quiting but it seems like an impossible task.