Hazard Identification : Each United Nations hazard class (with the exception of class 9) has a distinctive diamond shaped label bearing a pictogram for quick hazard recognition. Figure gives a colour chart for all the classes and subclasses.

Each label has a characteristic background colour. These colours convey the nature of different chemical substances as given below.

Colour                                                Nature

Orange                                                Explosive

Red                                                     Flammable

Blue                                                    Water reactive

Yellow                                                 Oxidiser

White                                                  Toxic or Infectious

White or Yellow and White                     Radioactive

Black and White                                   Corrosive

All the classes are discussed briefly in the following paragraphs.