On a recent inspection of a Hi-rise residential building, I tested the exhaust ductwork in the kitchen and bathrooms. Since this system is part of the building it should constantly be drawing air.
By holding a napkin in front of the intake vent, I discovered that it was not drawing air. Upon questioning the building super, I discovered that not only was the blower fan not working, but the penetration through the roof was severed and the roof sealed. The exhaust was just dumping into the space between the top floor ceiling and the roof deck.
Some residents installed their own blowers which were exhausting into this system.
I would hate to live on the upper floors when someone is cooking some weird food or especially the day after someone cooks some weird food! :vomit: