A chemical fume hood is a type of ventilation chamber designed to limit exposure to hazardous fumes. It isn’t a sterile environment, but it is crucial for working with items that otherwise  aren’t fit for working on a lab bench, like anything flammable, corrosive, or has gasses that can be inhaled, as it uses ducts to vent all the fumes from hazardous materials outside of the work area and the building. To create this ventilation effect, fume hoods are designed to have a constant flow of air circulating through the space, creating a barrier between the inside and outside of the space.