UNnumber

A UN number, short for United Nations number, is a four-digit code used to identify hazardous substances and articles in the transport of dangerous goods. It is part of a global system designed to facilitate safe handling, packaging, labeling, and emergency response. Each UN number corresponds to a specific substance or article and is used consistently across different modes of transport.

UN numbers are used on transport documents, hazard labels and placards, and in emergency information to help responders and carriers quickly determine the nature of the material. The same four-digit code is intended to provide a common reference across road, rail, sea, and air transport, with the detailed requirements for packaging, labeling, and handling derived from the associated proper shipping name, hazard class, and packing group.

The UN numbers and their classifications are published in the UN Recommendations on the Transport of Dangerous Goods (Model Regulations). These recommendations form the basis for national and international regulations such as the ADR (road), RID (rail), IMDG Code (sea), and IATA Dangerous Goods Regulations (air). The list is periodically updated, and new UN numbers may be added as new materials are regulated or existing entries are refined.

For safety and compliance, organizations consult official UN lists or authorized databases to verify the correct UN number, proper shipping name, hazard class, packing instructions, and labeling. Accurate UN numbering supports consistent communication, regulatory compliance, and effective emergency response across the global transport system.