Staircases

My bathroom smells faintly of cigarette smoke. Which is odd, for a couple of reasons.

1)Three of the fours walls face the rest of my apartment or the staircase.
2)There aren't any ducts in my bathroom.
3)The rest of my apartment smells fine.

Maybe it's just me.

I otherwise love my apartment. It is very cosy and I like the small size. I know exactly where everything is (okay, everything but one my knee guards. That could be anywhere.) and I have just enough space to move freely. I wouldn't mind having a staircase, but I don't actually want another room.