A ductless range hood is a type of exhaust fan that recirculates air through filters, rather than existing ductwork. Charcoal filters are the most common type of filter used with a ductless range hood.
Ductless range hoods work, but not as well as duct hoods. One of the biggest pros of a ductless range hood is that it can be installed in almost any setting, including on your wall, over top of a kitchen island, or even on top of a custom cooking surface.
Ductless ranges often come at a cheaper price than when compared to traditional, 30-inch range hood attached to a duct system, but they don't remove air pollutants as easily.
Ductless range hoods may be a good temporary option but most people prefer to vent range hoods to the outside because it is more efficient at getting rid of kitchen pollutants.