Chemical fume hoods, when used properly, are one of the most reliable engineering controls in the laboratory. They protect workers by Containing vapors, dusts, gases, and fumes generated within the hood, and removing them as air flows into the hood and then out via the laboratory exhaust system.

The purpose of a chemical fume hood is to prevent the release of hazardous substances into the general laboratory space by controlling and then exhausting hazardous and/or odorous chemicals.

Fume hood work

A fume hood is a ventilated enclosure in which gases, vapors, and fumes are contained. An exhaust fan situated on the top of the laboratory building pulls air and airborne contaminants through connected ductwork and exhausts them to the atmosphere. ... The slots and baffles direct the air being exhausted.

Fume hoods should be used when working with toxic compounds or compounds with a boiling point below 120°C. Fume hoods, or other effective local ventilation, must be provided and used when the materials used will exceed exposure limits in the laboratory.