According to the EPA (Environmental Protection Agency), an attached garage (which most of us have these days), is one of the biggest contributors to poor indoor air quality in your home. Car exhaust contains many known cancer-causing chemicals, and it can migrate into living spaces through doors, or cracks in walls or ceilings adjacent to the garage. Other pollutants commonly found in garages include benzene from lawn mowers and power tools, pesticides used in your garden, toxic cleaning agents, and the chemicals contained in paint and adhesives. One or all of these items are probably sitting in yours right now!

But properly designed and sealed garages can keep this polluted air out of your home. You can also use foams, caulking, or weatherstripping to create a barrier between the garage and your living spaces. Be sure to completely seal garage walls and celings adjacent to the interior. Doors should have full wetherstripping and sealed thresholds. If using a spray-applied foan, be sure it creates a complete air barrier. 

As an additional measure, install an exhaust fan in the garage on th eopposite wall from the door into the home. It can be triggered by an electric garage door system and put on a timer to run after the door has opened or closed.