The NFPA hazard rating system refers to a safety standard by the National Fire Prevention Association (NFPA) that outlines a hazard rating system for emergency personnel.
The NFPA 704 standard also defines the necessary signage and information that needs to be displayed to alert personnel of the type of hazardous materials that are present.
This NFPA hazard rating system includes three color codes and five intensity levels. Each color code (blue, red, and yellow) of the hazard rating system corresponds to a hazard: health, fire, and instability (denotation or chemical change).
Within each colored section, a numerical rating is given to the hazard. The ratings range from 0 to 4. A rating of 4 is the highest. If a 4 is in the red section of the hazard rating system, then the material should be considered highly flammable and therefore dangerous.
Refer to the NFPA Hazard Ratings and Permit Thresholds PDF for color codes and ratings.
Visit the Caution Signs and Warning Signs page for more information.