What is a UN number?

The term "UN" when discussing hazardous waste refers to the United Nations system for classifying and labeling hazardous materials, including waste. This system is part of the Globally Harmonised System of Classification and Labeling of Chemicals (GHS), which the UN developed to standardise and harmonise the classification and labeling of chemicals worldwide.


Under this system, hazardous materials are categorised based on specific criteria that relate to their physical, health, and environmental hazards. Each hazardous material or waste is assigned a unique UN number, often referred to as a UN ID or UN number. This number is a four-digit code used to identify hazardous substances or articles (such as explosives, flammable liquids, or toxic substances) across global transport and regulatory frameworks.


The use of UN numbers helps to ensure safe handling, transport, and disposal of hazardous materials by providing a common language and set of symbols that are recognisable internationally. This facilitates better emergency responses and reduces risks associated with hazardous materials management. Therefore it is important to label hazardous waste with stickers containing the UN number.