Learn the National Fire Protection Association's Chemical Hazard Labels

Chemicals are a part of our everyday life, but not all of them are necessarily dangerous or flammable. For those that have the potential to be quite dangerous, however, the National Fire Protection Association (NFPA) has developed a warning label to help inform users of the hazards related to the chemical, especially those with industrial uses. The label is a diamond divided into four colored sections — red, blue, yellow, and white — each section representing a specific aspect of the chemical. Numbers within each section give more information about the chemical’s health, fire, reactivity, and other miscellaneous effects.


The red section of the diamond provides data on the flammability of the chemical. There are certain conditions under which chemicals may burst into flame, and this section of the diamond explains those circumstances in which a chemical may burn. Within this section is a number between zero and four.

0-Zero indicates that the material will not burn in any circumstance.

1-One means that the temperature must be above two hundred degrees Fahrenheit for the substance to burst into flame.

2-Two says it might burst into flame between one hundred and two hundred degrees.

3-Three says it can ignite between seventy-three and one hundred degrees.

4-Four means that temperatures under seventy-three degrees can be sufficient to make it burst into flame.

As long as the chemical is kept out of the temperature range indicated in the red section of the diamond, the danger of fire should be low.


Blue informs people as to the potential health hazard of the chemical and its toxicity in the short-term. Toxicity is measured with the numbers zero through four.

0-Zero indicating that the chemical poses no short-term health threat. It should be noted, however, that such a chemical could still pose a long-term health threat if a person is exposed to it consistently.

1-The number one in the blue section of the diamond says the chemical is slightly hazardous.

2-Two means it is hazardous.

3-Three indicates the chemical is an extreme danger.

4-Four says short-term exposure can be deadly.

These numbers are especially beneficial for EMT personnel who are called upon to treat chemical accident victims as they can reveal what kind of gear these rescuers need to wear when treating victims.


On the NFPA diamond, the yellow section measures reactivity or the likelihood of the material exploding or detonating. Again, the rating is somewhere between zero and four.

0-Zero indicating that the chemical is stable.

1-One says the chemical becomes unstable when it is heated.

2-Number two indicates it can be very chemically reactive and explode if water contacts it.

3-The number three means it can detonate under heat or vibration.

4-Four meaning that it is very likely to detonate.

Those who pay close attention to this aspect of the rating are not likely to have an unexpected explosion occur on their watch.


The white section of the NFPA diamond is used to identify chemicals that are especially water reactive or that will respond with greater combustion when fuel is added to a fire in which they are involved.

W-An unusually water-reactive chemical will be identified with a "w" that has a line drawn through.

OX-An OX will identify those chemicals that can increase a fire’s intensity.

Whether a solid, liquid, or gas, nearly every chemical is potentially flammable, explosive, toxic, or has another special hazard. The NFPA warning label is a handy system for keeping people safe from the dangers many chemicals present.

For more information on the NFPA rating and chemical safety, consult the following links:

Chemical Safety Bibliography — an extensive bibliography of works related to chemical safety

Degree of Hazard — a more thorough guide to what the NFPA labeling system means

Healthcare Environmental Resource Center — overview of chemical labeling systems including that of the National Fire Protection Association

National Fire Protection Association — the official website of the National Fire Protection Association

American Coatings Association — a list with some frequently asked questions related to NFPA labels

NFPA Hazard Rating System — more data on the NFPA hazard rating system

NFPA Rating for Common Chemicals — New Mexico State University gives the NFPA ratings for several common chemicals