Cars are built to mostly recirculate the cabin air when the recirculate option is turned on. Note that cabins are not fully sealed from the outside. You have mu

Cars are built to mostly recirculate the cabin air when the recirculate option is turned on. Note that cabins are not fully sealed from the outside. You have multiple vents located throughout the car whose job is to keep the outside elements away and let the cabin "breathe". Leave it on recirculate unless you are defrosting your windows.