A/C I smell my neighbor's smoke when I turn on my A/C
Any gaps, or even the smallest crack in a unit will cause orders to migrate. It is about Positive & negative airflow in how to keep this from happening. You may want to look at a filter that helps to filter those particulates out of the air when the unit is running, also seal any cracks under your front door with a door sweep, or door sock. Basically when your unit is running, it is pulling the air from the hall. Bad thing about apartments & condos, is most were designed before air quality was placed into the thought. Especially those buildings that are over fifty years or older.