Where should kitchen exhaust fans terminate?

Kitchen exhaust fans should vent outside to remove excess humidity, smoke, steam, and cooking odors from the kitchen:

Improves air quality

Venting a kitchen exhaust fan outside removes smoke, steam, and cooking odors from the kitchen, which improves air quality and reduces the risk of fire hazards.

Prevents mold and mildew

If a kitchen exhaust fan doesn't vent outside, humidity can build up and create an environment where mold and mildew can thrive.

Reduces maintenance

Ducted range hoods require less maintenance than ductless hoods because grease and odors are vented outside, reducing the need for frequent filter replacements.