Which NFPA 704 color code corresponds to health hazard?

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

Answer: (A)

NFPA 704 uses a color-coded hazard diamond to convey different risks at a glance. Each color corresponds to a type of hazard: blue indicates health hazard, red indicates flammability, yellow indicates reactivity or instability, and white is for special information (such as specific reversibility, compatibility, or PPE notes). So health risk is signaled by blue because it tells you about potential health effects from exposure, like toxicity or irritation, and guides how you protect yourself (pacing, PPE, exposure limits). The other colors point to different dangers—you’d look at red for how easily something catches fire, yellow for how reactive it is, and white for any special handling instructions.