How to deal with roommates who smoke?

I’m thinking of moving into an apartment with two friends, both of whom smoke inside. I checked it out today and it doesn’t smell too bad (and it’s pretty big too), but I’m wondering what I can do to minimize the second-hand smoke, especially when I’m in my room. I can’t really ask them to stop since they’d be pulling me in, and this is the only real drawback to living there. Thanks!