What does a health rating of 4 indicate in the NFPA 704 classification?

What does a health rating of 4 indicate in the NFPA 704 classification?

• A. Hazardous
• B. Caution
• C. Extreme Danger
• D. Deadly

Answer: (D)

NFPA 704 conveys acute health hazard with a blue health rating that runs from 0 to 4. A rating of 4 is the highest level and means exposure could be fatal or life‑threatening; even brief contact could result in death, so extreme precautions, avoidance of exposure, and rapid emergency response are required. This is why the term that matches exactly is Deadly. The other labels describe far lower or non-specific levels of risk and don’t reflect the true severity indicated by a 4 rating.

NFPA 704 conveys acute health hazard with a blue health rating that runs from 0 to 4. A rating of 4 is the highest level and means exposure could be fatal or life‑threatening; even brief contact could result in death, so extreme precautions, avoidance of exposure, and rapid emergency response are required. This is why the term that matches exactly is Deadly. The other labels describe far lower or non-specific levels of risk and don’t reflect the true severity indicated by a 4 rating.