What sign is posted in fume hoods where volatile radioactive materials are used?

The appropriate sign to be posted in fume hoods where volatile radioactive materials are used is "Caution - airborne radioactivity area." This designation is essential because it alerts personnel to the potential presence of radioactive materials in the air, which could pose inhalation or contamination risks. Fume hoods are specifically designed to contain and exhaust hazardous fumes and vapors, including those that might be radioactive.

By using this signage, it ensures that individuals working in proximity to the fume hood are aware of and can take necessary precautions when handling, dispensing, or analyzing volatile radioactive substances. The sign highlights the need for appropriate personal protective equipment (PPE) and adherence to safety protocols while working in that environment, thereby minimizing exposure and enhancing overall safety.

In contrast, the other signs mentioned focus on different types of hazards and would not be relevant in this specific context involving volatile radioactive materials.