I've had a fan on and my windows open. The ventilation systems for the apartments are hooked together. It's flowing through the vents into my apartment.
You need to reverse the airflow. Or block the vent.
Now you know why Tom Ridge wanted you to get some plastic and duct tape.
In a pinch, you can use a plastic trash bag, and even scotch tape.
Through the vents?
That means it draws the air from each room and shares it with all the other rooms.
Guess you love smokers and legionnaires disease.