The NFPA hazard identification label is a large diamond that contains four smaller diamonds of different colors. It was created to quickly alert emergency personnel to the risks associated with hazardous chemicals. The different colored diamonds indicate:
- Fire hazards (red diamond)
- Health hazards (blue diamond)
- Reactivity hazards (yellow diamond)
- Special hazards related to a chemical (white diamond)
The red, blue, and yellow diamonds use a numbering system from 0 - 4 to indicate the severity of each fire, health, and reactivity hazard, respectively. "0" indicates no hazard, and "4" indicates the most severe hazard.
The white diamond uses different symbols to indicate different special hazards. The diamond can include the following:
- A strike-out W (
W), for when the chemical reacts with water.
- OX, for when the chemical is an oxidizer.
- COR, for when the chemical is corrosive.
- The radioactivity symbol for when the chemical is radioactive.
Some laboratories may use this diamond system to label secondary containers of hazardous chemicals that remain in the laboratory.