If NFPA placard is blue, what hazard does it indicate?

• A. Flammability
• B. Health Hazard
• C. Instability
• D. Special Hazard

Answer: (B)

A blue section on an NFPA 704 placard signals a health hazard. The NFPA 704 diamond uses four colors to convey risk quickly: blue for health, red for flammability, yellow for reactivity/instability, and white for special hazards. Each colored section can include a number from 0 to 4, where higher numbers mean greater hazard; a blue area with a number indicates the level of potential health risk from exposure, such as irritation, toxicity, or other adverse effects. In practice, seeing blue means you should prioritize minimizing exposure and using appropriate protective equipment (gloves, eye protection, possibly a respirator) when handling or responding to the material. The other colors indicate flammability (red), instability/reactivity (yellow), and any special hazards (white).