GHS is structured in building blocks that correspond to the different hazard classes and categories used to describe the nature of the hazards of hazardous substances/mixtures.

Click for a graphical overview of the GHS hazard classes

The building blocks approach allows each Country/Region to choose which hazard classes and categories (building blocks) to implement in the local legislation. This can lead to differences in classification for a given substance/mixture, even if the classification criteria used are the same (once a building block is chosen, it is not possible to change the related criteria).

See GHS implementation - world map
See GHS implementation - description