What are GHS codes?

When most people think of the GHS system, they think of the various pictograms representing different hazards. While that is certainly the most well-known aspect of GHS, it is really just the beginning. GHS also includes standards and information about hazard statements, signal words, and more. One very important part of the GHS system are the H-Codes, which are used to break down various types of hazards into specific types.

H Code Categories

There are dozens of different hazard codes that are included in this system, which can make it difficult to memorize them all. To help allow people to be able to quickly determine the general type of hazard that a specific code is referring to, the system is broken up into three different categories. All codes start with the letter H, and then three digits. The first digit after the “H” can be used to determine what category the specific code will fall within:

  • H2 – Anything that starts with an H2 will be a physical hazard.
  • H3 – Anything that starts with an H3 will be a health hazard.
  • H4 – Anything that starts with an H4 will be an environmental hazard.

Specific H Codes

To get more information about an H code, the next two digits will need to be looked at. This will reference a specific type of hazard within that category. For example, H203 is an explosive, fire, blast, or projection hazard. In most facilities there will only be a handful of different H codes used because of the type of work and the chemicals that are being used. This makes it easy for employees to memorize those codes that pertain to their environment so they can quickly understand what hazards are present in an area.


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