The tabletop fume hood, like other laboratory fume hoods, is a ventilation system that is designed to filter and/or exhaust gasses, chemical fumes, and vapors. They also simultaneously act as a barrier to lab personnel and the lab itself, containing spills and reducing exposure.
Most fume hoods are box-like structures with a vertical (most common) or horizontal sash window. The interior of the hood maintains a negative pressure which impedes the ability of contaminates from flowing out. This is coupled with a continuous drawing in of air into the chamber at a regulated rate.
These hoods are designed to be mounted to a lab bench or table top and can be ductless or use a ventilation duct. Ductless hoods allow for more portability and generally use HEPA filters whereas ducted ventilation hoods pull fumes into the building’s exhaust system where it is treated before being released outside.