What to do with smoke getting into ventilation?
I wrote a comment a while ago that suggested using a combination filter and charcoal filter in duct work to eliminate odors. I use them in my home since my wife hates most odors that others don't mind. I buy them from Home Depot and Lowes and the go by the name "The Web Absorber", cost around $10.00, and are a cut to size filter. You could also look in the furnace filter dept. and see if they carry a charcoal furnace filter that you could fit into the fresh air duct. Charcoal should filter out most if not all the odor.