Smell traveling form vents?

I live in a new apartment , maybe around 4 years old? And whenever I go into my bathroom, I can smell everything coming out of my roommates room, which is across the living room. Sometimes I can smell her room faintly in my own room as well. I don’t understand why! Honestly I don’t like the way her room smells because it reeks of weed and cigar wrappers and it is just an unpleasant and triggering smell for me. Has anyone else had his occur in their home?I keep a candle warmer lit in my bathroom and regular candles lit in my room to combat the smell but it’s just so annoying to deal with 🙄 I’ve lived in so many different places and this is the first place I’ve been too where the smells travel through the vents so badly . The living room doesn’t smell like her room, only mine and it’s just so weird .