For effective local contaminant capture, what should the ducting do?

• A. Return air to the main HVAC
• B. Lead directly outdoors to capture local contaminants
• C. Mix with other indoor air before exhausting
• D. Vent indoors near occupants

Answer: (B)

To capture contaminants effectively at their source, the ducting should pull the pollutants directly to the outdoors. This keeps the contaminants from circulating back into the indoor environment or mixing with other indoor air. When exhaust is routed directly outdoors, you prevent re-entrainment into the building and avoid exposing occupants, which would happen if the air were vented back inside, mixed with other indoor air, or discharged near people. A dedicated local exhaust path that leads straight outside is the proper approach, with discharge directed away from intakes and windows and designed to maintain a sufficient capture rate at the source.