These are used to control the hazardous emissions of powders, dust or vapors during powder dispensing, product sampling, or bag dispensing, etc., without risk to the operator or environment. The downdraught prevents airborne dusts caused by weighing and dispensing operations rising into the operator's breathing zone. The air forced downwards is extracted at low level into the booth's filtration system where dust particles are contained at each level of filtration prior to being re-circulated back into the booths' air stream.