Job Aid: NFPA Numerical System

Purpose: Use this job aid to learn about the National Fire Protection Association (NFPA) numerical system.

The NFPA system uses a numeric code (0-4) in each color-coded hazard diamond, where the number in each section represents the severity of the hazard.

NFPA levels for health hazards – blue section
Level	Description
4	Danger – may be fatal upon short exposure. Specialized protective equipment required.
3	Warning – corrosive or toxic. Avoid skin contact or inhalation.
2	Warning – may be harmful if inhaled or absorbed.
1	Caution – may be irritating.
0	No unusual hazard.

NFPA levels for fire hazards – red section
Level	Description
4	Danger – flammable gas or extremely flammable liquid.
3	Warning – flammable liquid flash point below 100° Fahrenheit.
2	Caution – combustible liquid flash point of 100° Fahrenheit to 200° Fahrenheit.
1	Combustible if heated.
0	Not combustible.

NFPA levels for instability hazards – yellow section
Level	Description
4	Danger – explosive material at room temperature.
3	Danger – may be explosive if shocked, heated under confinement, or mixed with water.
2	Warning – unstable, or may react violently if mixed with water.
1	Caution – may react if heated or mixed with water, but not violently.
0	Stable – not reactive when mixed with water.

Prior to 1996, the yellow "Instability" section was titled "Reactivity." The name was changed because it didn't clearly differentiate between a "reactive hazard" and the "chemical reactivity" of the material. The numerical ratings and their meaning remain unchanged.

NFPA levels for special key notice hazards – white section
Level	Description
W	Water reactive.
OX	Oxidizing agent.

Course: Hazard Communication: An Employee's Right to Know
Topic: Warning Labels