Which statement is true about using a fume hood?

• A. Ensure exhaust is operating before use.
• B. The hood shall be kept closed, except during apparatus set-up or when working within the hood.
• C. The hood may be used as permanent storage for volatile chemicals when no cabinet is available.
• D. Remove contaminated items from the hood without decontamination.

Answer: (A)

Fume hoods rely on active ventilation to pull contaminants away from the user. The key safety step is to confirm that the exhaust system is operating before you begin work, because proper containment depends on airflow. If the exhaust is off, fumes can escape into the lab regardless of sash position, making the setup unsafe. Using the hood as permanent storage for volatile chemicals blocks airflow and is not permitted. Removing contaminated items without decontaminating can spread hazards, so decontamination must come before removal. Keeping the hood closed when not actively using it is sensible, but the critical factor that makes the practice safe is ensuring the exhaust is on before you start.