Dangerous Goods Classes and Symbols - ChemSafetyPro.COM There are 9 dangerous goods classes. Substances (including substances and mixtures), and articles are assigned to one of the following 9 classes according to the most predominant hazards they pose in transport. Some of the classes can be further divided into divisions, e.g., Class 1, while others do not have sub-divisions, e.g., Class 3.