The class number does not correspond to the degree of hazard of the cargo. Depending on the types of danger, as well as their physical, chemical and biological properties, all dangerous goods are divided into the following classes of danger:

• Сlass 1 explosives and articles; 
• Сlass 2 gases; 
• Сlass 3 flammable liquids; 
• Class 4.1 flammable solids, self-reactive substances, solid desensitized explosives; 
• Сlass 4.2 substances capable of spontaneous combustion; 
• Class 4.3 substances that emit flammable gases in contact with water; 
• Сlass 5.1 oxidizing substances; 
• Сlass 5.2 organic peroxides; 
• Сlass 6.1 toxic substances; 
• Сlass 6.2 infectious substances; 
• Сlass 7 radioactive materials;
• Сlass 8 corrosive substances;
• Сlass 9 other dangerous substances and products.