What is the purpose of a fume hood in a laboratory or controlled environment?

• A. To filter air returning into the room for energy efficiency.
• B. To protect the user by capturing and exhausting hazardous fumes, vapors, and dust away from breathing zone.
• C. To provide a passive ventilation path for room air mixing.
• D. To house chemical storage shelves and PPE.

Answer: (B)

The main idea is that a fume hood protects you by capturing hazardous fumes, vapors, and dust at the source and exhausting them away from your breathing zone. It creates a controlled airflow across the opening, drawing contaminants into the hood rather than letting them drift into the room. The sash helps regulate the opening and maintain a protective face velocity, so fumes stay inside the enclosure as you work. The exhaust carries the contaminated air outside or through appropriate filtration, keeping the lab environment safer and reducing exposure during chemical handling. This purpose is distinct from energy-efficient recirculation of room air, a general ventilation path for room air mixing, or storage-oriented uses, which is why a fume hood is not meant for those functions.