UN numbers — the 4-digit 'name tag'

Every dangerous substance in the world is given a 4-digit 'UN number' so it can be identified the same way everywhere — on a lorry in Britain, a ship leaving Rotterdam or a parcel landing in Dubai. The 'UN' stands for United Nations. Petrol is UN1203. Sulphuric acid is UN1830. Lithium-ion batteries are UN3480. The UN number is like a name tag the whole world agrees on.

A UN number is a 4-digit ID for a substance.

Three real UN numbers you'll meet again and again in this app — and in real life: UN1203 = petrol (motor spirit) — Class 3 flammable liquid. UN1830 = sulphuric acid — Class 8 corrosive. UN3480 = lithium-ion batteries — Class 9 miscellaneous. Don't try to memorise them yet; just know they're real, fixed and worldwide.

UN1203 = petrol — Class 3 (flammable liquid).

Lots of numbers float around in transport. A UN number is always 4 digits, often written as 'UN1203'. It's NOT a postcode, a delivery time, an ISO standard or a vehicle plate. If a colleague says 'this is UN-stuff', they probably mean a UN number — that 4-digit substance ID. When in doubt, look it up in the Dangerous Goods List (ADR Table A).

A UN number is always 4 digits, e.g. UN1203.