UN number

It is not possible to deduce the hazard class(es) of a substance from its UN number: they have to be looked up in a table.

UN numbers range from UN 0004 to about UN 3550 (UN 0001 – UN 0003 are no longer in use) and are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods.

They are published as part of their Recommendations on the Transport of Dangerous Goods, also known as the Orange Book.

These recommendations are adopted by the regulatory organization responsible for the different modes of transport.

Substances with an ID number are associated with proper shipping names recognized by the ICAO Technical Instructions.