UN Numbers and NA Numbers
A UN number is a four-digit code assigned by the United Nations to a hazardous substance or group of substances so that everyone in the transport chain identifies it the same way. An NA number is a similar four-digit code, starting with “NA”, that the U.S. Department of Transportation assigns for domestic shipments when no UN number applies.
What the numbers are for
The number appears on shipping papers, on placards and orange panels, and on container markings. Emergency responders use it to look up the material in the Emergency Response Guidebook (ERG) in seconds, even if the product name is not known or is in another language. One UN number can cover many products with similar hazards, such as flammable liquids not otherwise specified. Because the numbers are assigned to the shipping description, not the chemical itself, the same chemical may have different numbers in different forms (for example a solution and a solid).
UN numbers versus NA numbers
| UN number | NA number | |
|---|---|---|
| Format | UN + 4 digits (for example UN1203) | NA + 4 digits |
| Assigned by | United Nations committee of experts | U.S. DOT |
| Used for | International and domestic transport | Domestic U.S. transport (and by agreement with Canada) when no UN number fits |
| Defined in | The Hazardous Materials Table, 49 CFR 172.101 | |
See the glossary entries for UN number and NA number.
How to find the UN number on an SDS
- Go to Section 14: Transport information.
- Find the line labeled UN number (or UN/ID number). It often has separate rows for DOT, IMDG (sea) and IATA (air).
- Read the proper shipping name, hazard class and packing group next to it. Together these form the full shipping description.
- Check for special notes: marine pollutant, limited quantity, reportable quantity, or toxic inhalation hazard.
If Section 14 says “not regulated” or “not applicable”, the product, in that form and package, is not subject to hazmat shipping rules. That can change with the quantity, packaging or temperature.
ERG guide numbers
The Emergency Response Guidebook lists UN and NA numbers in a numeric index. Each entry points to a three-digit guide number, a page of first-response advice: potential hazards, public safety distances, fire and spill response and first aid. Some SDSs print the guide number in Section 14. If not, look the UN number up in the current edition of the ERG. The guidebook is for the first minutes of an incident and is no substitute for the SDS or expert advice.
Common examples
| UN number | Material | Class |
|---|---|---|
| UN1203 | Gasoline | 3 (flammable liquid) |
| UN1090 | Acetone | 3 (flammable liquid) |
| UN1830 | Sulfuric acid | 8 (corrosive) |
| UN1824 | Sodium hydroxide solution | 8 (corrosive) |
| UN1017 | Chlorine | 2.3 (poison gas) |
| UN1066 | Nitrogen, compressed | 2.2 (non-flammable gas) |
Examples are for illustration. Confirm the UN number, name and class for your exact product and concentration against its SDS and the Hazardous Materials Table.
Related reading
Frequently asked questions
What is a UN number?
A UN number is a four-digit identifier assigned by the United Nations to a hazardous substance or group of substances, used in international transport. UN1203, for example, identifies gasoline.
What is an NA number?
An NA number is a four-digit identifier starting with NA that is assigned by the U.S. DOT for domestic transport of materials that do not have a UN number, or that have a different description in the U.S.
Where is the UN number on an SDS?
In Section 14 (Transport information), alongside the proper shipping name, hazard class and packing group.
What is an ERG guide number?
The ERG guide number is a three-digit number that points to a page in the Emergency Response Guidebook with initial response advice for that material. It is found by looking up the UN number in the guidebook.