There are 9 classes of dangerous goods in the standard UN-based transport classification system used worldwide for road, rail, sea, and air transport.

Quick Scoop

Under the UN Model Regulations and aligned systems like ADR (road in Europe), TDG (Canada), and the IMDG/ICAO rules, dangerous goods are grouped into 9 main classes based on the type of hazard they present.

The 9 main classes

  • Class 1 – Explosives (e.g., fireworks, ammunition).
  • Class 2 – Gases (flammable, non-flammable, or toxic gases such as propane or chlorine).
  • Class 3 – Flammable liquids (e.g., petrol, solvents, alcohols).
  • Class 4 – Flammable solids; substances liable to spontaneous combustion; substances which, in contact with water, emit flammable gases.
  • Class 5 – Oxidizing substances and organic peroxides (can intensify fire or decompose dangerously).
  • Class 6 – Toxic and infectious substances (e.g., certain pesticides, medical infectious waste).
  • Class 7 – Radioactive material.
  • Class 8 – Corrosives (e.g., strong acids and alkalis).
  • Class 9 – Miscellaneous dangerous goods (hazardous but not fitting classes 1–8, such as dry ice or some lithium batteries in certain contexts).

Many of these classes are further divided into divisions (like Class 1.1–1.6 for different explosive behaviors, or 2.1–2.3 for different gas types), but the headline answer to “how many classes of dangerous goods are there” is nine.

Information gathered from public forums or data available on the internet and portrayed here.