Which NFPA 704 color indicates special information such as water reactivity?

• A. Blue
• B. Red
• C. Yellow
• D. White

Answer: (D)

The white area in the NFPA 704 diamond is reserved for special information about hazards that don’t fit into the three main categories. While blue, red, and yellow show health, flammability, and reactivity with numeric ratings, the white section can carry symbols or letters that flag specific hazards like water reactivity or oxidizers. For example, a W with a strike-through in the white area signals water reactivity, alerting responders to avoid water with that material. If there are no special hazards, this white area is often left blank. That’s why this question points to white as the color indicating special information such as water reactivity.