Which statement describes proper practice when using a fume hood?

• A. Room air should be drawn into the fume hood
• B. The window on the front of the fume hood is called a stash
• C. All work should be done at least 6 inches inside the hood
• D. Exhaust air from fume hoods is recycled back through the lab

Answer: (C)

Using a fume hood properly is all about keeping hazardous vapors contained while you work. The key idea is to place your work well inside the hood so the airflow can capture and pull fumes away from you and prevent them from leaking out around the sash. Keeping everything at least six inches inside the hood gives the capture velocity the hood is designed for, so even when you move containers or your arms, the contaminants stay in the hood and are vented away. If you work too close to the front, turbulence and poor capture can allow vapors to escape and reach you or the room.

The front window is called a sash, not a stash, and it’s there to control access and airflow. It’s not a guideline about how far to work; it’s a control for safety.

Exhaust from fume hoods should be vented outside the building, not recycled back into the lab. Recirculating air defeats containment and can expose people to hazardous vapors.