The nine classes
The same nine-class system is used for air, ocean and US ground transport. Some classes are split into divisions that describe the specific hazard.
| Class | Name | Divisions | Examples |
|---|---|---|---|
| 1 | Explosives | 1.1 mass explosion hazard; 1.2 projection hazard; 1.3 fire hazard with minor blast or projection; 1.4 no significant hazard; 1.5 very insensitive; 1.6 extremely insensitive | Fireworks, ammunition, flares |
| 2 | Gases | 2.1 flammable gas; 2.2 non-flammable, non-toxic gas; 2.3 toxic gas | Propane, compressed air, aerosols, chlorine |
| 3 | Flammable liquids | No divisions | Paint, gasoline, alcohol, adhesives, perfume |
| 4 | Flammable solids and reactive substances | 4.1 flammable solids; 4.2 spontaneously combustible; 4.3 dangerous when wet | Matches, certain metal powders, calcium carbide |
| 5 | Oxidizers and organic peroxides | 5.1 oxidizing substances; 5.2 organic peroxides | Pool chemicals, hydrogen peroxide solutions, bleaching agents |
| 6 | Toxic and infectious substances | 6.1 toxic substances; 6.2 infectious substances | Pesticides, certain lab samples and clinical specimens |
| 7 | Radioactive material | No divisions | Certain medical and industrial isotopes |
| 8 | Corrosives | No divisions | Acids, battery fluid, drain cleaners |
| 9 | Miscellaneous dangerous goods | No divisions | Lithium batteries, dry ice, magnetized materials, environmentally hazardous substances |
Packing groups
For many classes, a material is also assigned a packing group that shows how dangerous it is. Packing group I indicates great danger, II medium danger and III minor danger. The packing group affects which packaging can be used and the quantity limits that apply.
Subsidiary risks
Some materials present more than one hazard, for example a liquid that is both flammable and corrosive. The regulations assign a primary class and, where needed, one or more subsidiary hazards. Each must be shown on the paperwork and the package labels.
Why classification comes first
Everything else in the shipment depends on getting the classification right: the packaging you can use, the labels and marks, the paperwork, and the limits for each mode of transport. Classification is the shipper's responsibility. A Safety Data Sheet is a starting point, but it is not a substitute for classification against the regulations.