 air it's basically putting a mist up into the air and so that you want to get ducted and go outside that's why it's always so greasy up inside of the hood is it's one of those things you want to deal with to make sure you got it under control so that is the one of the biggest things as far as to contribute to bad air quality in your home is not using that vent fan and if you've got a recycling one where you have that little charcoal filter that kicks it back into the room