In a Local Exhaust Ventilation System, which component collects the contaminants?

• A. Hood
• B. Duct
• C. Exhaust
• D. Fan

Answer: (A)

The key idea is that local exhaust ventilation works by capturing contaminants right at the source. The hood is the capture device that sits over or near the emission point to pull contaminants into the system. Its job is to create a zone of capture so the pollutants don’t spread into the worker’s breathing zone. The duct is just the pathway that carries the captured air away; it doesn’t collect contaminants. The fan provides the airflow and suction, but without the hood first capturing the contaminants, contaminants would not be pulled into the system efficiently. The exhaust is simply the outlet where the air leaves the system to be discharged or filtered, not the point of collection. So, the component that actually collects contaminants is the hood.