You need to pressurize your area, which will keep the smoke from entering.
Use the fan to blow air into the room from the outside WITH ALL OTHER WINDOWS CLOSED. This will prove the theory.
There are air-to-air heat exchangers available that will blow outside air into the room/house and exchange the heat with the outgoing air so it doesn't take as much energy to replace the room air.
Also check for sources of leakage from the other units. Things like wall outlets in the common walls could be a source. There are kits available to seal these up.
I Wish You The Best Of Luck,