GHS Hazard Classes
A hazard class is the type of hazard a chemical presents, such as flammable liquids, skin corrosion or acute toxicity. Within each class, a category (1, 2, 3 and so on) shows the severity. The GHS has 35 hazard classes in our data, grouped into physical, health and environmental hazards. Select one for its categories, hazard statements and pictograms.
Physical hazards (16)
H200–H299: hazards from the physical properties of a chemical, such as fire, explosion, pressure and corrosion to metals.
Health hazards (16)
H300–H399: harm to people through swallowing, skin or eye contact, or inhalation, including toxicity, corrosion, sensitization, cancer and reproductive effects.
Environmental hazards (3)
H400–H499: hazards to the aquatic environment and, in some systems, to the ozone layer.
Frequently asked questions
What is a GHS hazard class?
A hazard class is the type of physical, health or environmental hazard, such as flammable liquids, skin corrosion or acute toxicity. Each class is split into categories that show how severe the hazard is.
What is the difference between a hazard class and a category?
The class names the hazard (for example flammable liquids). The category gives its severity within that class. Category 1 is generally the most severe, with higher numbers being less severe.
How is a chemical classified?
The supplier compares test data and other evidence for the chemical with the GHS criteria for each hazard class. The result decides the category, which in turn decides the pictogram, signal word and hazard statement on the label.
https://pubchem.ncbi.nlm.nih.gov/ghs/ghscode_10.txt (UN GHS Revision 10, retrieved 2026-10-12)