In using fume hoods, the following shall be done, except for:

• A. The hood may be used as a permanent storage area for volatile chemicals when an appropriate storage cabinet is not available.
• B. Ensure the exhaust is operating before using the hood.
• C. The hood shall be kept closed, except during apparatus set-up or when working within the hood.
• D. Items contaminated with odorous or hazardous materials should be removed from the hood only after decontamination or if placed in a closed outer container to avoid releasing contaminants into the laboratory air.

Answer: (A)

Fume hoods are designed to vent hazardous vapors away from you and the room, not to serve as storage spaces. Keeping volatile chemicals permanently stored inside a hood can block airflow, trap vapors, and create spills or leaks that the hood isn’t meant to handle. When the hood is used for ventilation, containers should be brought in for the necessary duration of the experiment and then moved to appropriate, approved storage elsewhere. This protects the containment system and reduces the risk of exposure or ignition.

The other practices reinforce safe hood use: making sure the exhaust is operating before you start ensures the hood is actively drawing fumes away from you; keeping the hood closed when you’re not actively setting up or working inside helps maintain proper containment and reduces drafts that could pull contaminants into the room; and removing odorous or hazardous items only after decontamination or placing them in a closed outer container prevents releasing contaminants into the laboratory air.