Furnace cold air Intake question?

[John DeFoor]

I have a condo that is a second floor unit. The heater is in a heater closet with the cold air intake under it opening up into the bottom of the furnace. Problem with this is the downstairs owners smoke and the furnace draws the smoke from their place through the and void and out the vents from the furnace. So it always smells like a chain smoker is in the condo no matter what. My plan was to seal off the intake void under the furnace insulate it heavily. My question is can I cut the lower panel or door on the front of the furnace where the intake fan is weld a great in and place for a filter then cut a hole in the closet door for air from my condo to supply intake of furnace thereby eliminating the void that currently draws all the smoke in. Also this is the only place bringing the smoke up in this condo? Any advice would be appreciated.