Plan on doing a hatch in February and want to brood chicks (after 3 weeks in house) in the attached garage but am concerned about fumes from the tractor and van. Brooder will be a refrigerator box with mesh top, ceramic heater hanging inside. I don't drive a lot, but would starting the van and pulling out, then closing garage door...then the return trip create enough fumes to asphyxiate chicks? Same scenario with tractor/snow thrower. Any thoughts??