# Hazardous Material Classification Systems

*Last updated: 2026-06-24*

> Transport operators, shippers, and customs authorities rely on hazardous material classification systems to assign substances and articles to standardised hazard categories based on their risk potential.

Transport operators, shippers, and customs authorities rely on hazardous material classification systems to assign substances and articles to standardised hazard categories based on their risk potential. All principal international frameworks – the IMDG Code (sea), ADR (road), RID (rail), and IATA-DGR (air) – draw on the UN Model Regulations (the Orange Book), which establishes nine main classes including explosives (Class 1), gases (Class 2), and flammable liquids (Class 3), and assigns a UN number to each substance. Correct classification is a fundamental compliance obligation, not a formality: it determines the packing group, labelling requirements, permitted transport quantities, and any applicable special provisions. Misclassification leads to shipment holds, regulatory fines, and significant liability exposure in the event of an incident. Because the cross-modal framework is largely harmonised, a classification established for one mode can generally be applied across others, provided any mode-specific exceptions are observed.

**Source:** [https://unece.org/transport/dangerous-goods/un-model-regulations-rev-23](https://unece.org/transport/dangerous-goods/un-model-regulations-rev-23)

## Quick Facts

| Property | Value |
|---|---|
| Term | Hazardous Material Classification Systems |
| Language | EN |
| Word count | 144 |
| Last updated | 2026-06-24 |
| Source | https://unece.org/transport/dangerous-goods/un-model-regulations-rev-23 |

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