A laboratory fume hood is a three-sided enclosure with an adjustable front opening. It is designed to capture, contain, and exhaust hazardous fumes generated inside its enclosure. Fume hoods accomplish this by exhausting air through the hood face to the outside of the building. Fumes are then drawn away from the worker's breathing zone. Because exposure to volatile chemicals is one of the top health and safety hazards to laboratory workers, a fume hood operates as a principle safety devise in a laboratory setting.

OSHA Fume Hood Fact Sheet