Try: 1203, gasoline, chlorine, sulfuric acid, diesel, acetone
What is a UN Number?
UN numbers are four-digit identification codes assigned to hazardous materials by the United Nations Committee of Experts on the Transport of Dangerous Goods. Every substance regulated for transport has a UN number that tells emergency responders exactly what they're dealing with. These numbers appear on shipping papers, placards, labels, and package markings.
When you see a four-digit number on the side of a tanker truck or rail car, that's the UN number. First responders use this number with the Emergency Response Guidebook (ERG) to identify hazards and determine initial protective actions. The 2024 ERG covers over 3,500 materials and is required equipment for hazmat transport under 49 CFR 172.602.
How to Use This Tool
Enter a UN number (like 1203 for gasoline) or type part of a material name (like "chlorine" or "sulfuric"). You can also filter by hazard class using the buttons above the results. Click any result card to expand it and see the full details including ERG guide number, packing group, and label requirements.
Materials flagged as TIH (Toxic by Inhalation) include initial isolation and protective action distances from the ERG green pages. These distances are critical during the first minutes of a spill response. For more on what to do in those first minutes, read our guide on spill response in the first 30 minutes.
Related Resources
This tool pairs well with our other compliance resources. Check your state's environmental penalty amounts to understand the financial stakes of a spill. Browse our spill response service guide to learn what contractors charge and how billing works. If you need testing done, our testing lab directory lists environmental labs by region. And if you need a contractor fast, our provider directory connects you with environmental service companies nationwide.