Different Hazard Classification Tools and Symbols

GHS, NFPA, and HMIS are different systems with different purposes to categorize hazards. They are not interchangeable. For additional information on Hazard Communication systems, please visit the OSHA website.


The Globally Harmonized System (GHS) of Classification and Labeling of Chemicals is used in UN regulation to help manufacturers classify materials and assign pictograms, signal words, and hazard statements. There is no universal scale and category numbering for classifications is not uniform throughout each category. For a detailed description of pictograms and their associations, please visit the OSHA website.

NFPA 704

The National Fire Protection Association (NFPA) system of classification is a fire protection warning system designed to help first responders with conditions of fire, chemical spills, and other emergency situations. The four parts of the diamond are for Health Hazard (Blue), Fire Hazard (Red), Reactivity (Yellow), and Specific Hazard (White). Health, Fire, and Reactivity receive a numeric rating from 0 to 4 based on the severity of hazard in that category, with 0 being non-hazardous and 4 being the most severe. Specific hazards include Oxidizer, Corrosive, Water Reactive, etc.

NFPA Ratings can be defined more generally as follows:


4 - Flash Point Below 73F
3 - Flash Point Below 100F
2 - Flash Point Below 200F
1 - Flash Point Above 200F
0 - Will Not Burn


4 - Deadly
3 - Extreme Danger
2 - Hazardous
1 - Slightly Hazardous
0 - Non-Hazardous


4 - May Detonate
3 - Shock and Heat May Detonate
2 - Violent Chemical Change
1 - Unstable if Heated
0 - Stable


The Hazardous Materials Identification System (HMIS) is designed to aid day-to-day employees in recognition of hazards. While similar to NFPA 704, there is a major difference in the last two sections of an HMIS hazard placard. Like NFPA 704, there is a space for Health Hazard (Blue) and Fire Hazard (Red). In addition, HMIS has a section for Physical Hazard (Orange) and Personal Projection (White). Like NFPA, these sections receive a rating from 0 to 4, with 0 indicating non-hazardous and 4 being the most severe.

In February 2013, an OSHA Brief stated: “Employers may continue to use rating systems such as National Fire Protection Association (NFPA) Diamonds or HIMS requirements for workplace labels as long as they are consistent with the requirements of the Hazard Communication Standard and the employees have immediate access to the specific hazard information [of the chemicals]. An employer using NFPA or HMIS labeling must, through training, ensure that its employees are fully aware of the hazards of the chemicals used.”