A downdraft vent is a form of kitchen range ventilation that clears the air of fumes by pulling smoke downward. It is a substitute for traditional updraft vents, which use the natural rising motion of smoke and fumes to pull them upward out of the kitchen while cooking.
Downdraft vents are integrated into the cooking appliance's surface and pull fumes through a duct that leads outside the room. They are effective for short range appliances or kitchens in which updraft vents are not practical. Downward vents are ineffective unless they are vented with ducts outside the home. They recirculate air and at times remove moisture, odor and heat.