Hazmat paperwork is full of abbreviations. New shippers, warehouse staff and buyers can feel lost when carriers talk about PSNs, PGs and ERGs. This glossary explains the terms you will see most often, in plain language.
Identification terms
Proper shipping name (PSN): The official name of a regulated material as listed in the Hazardous Materials Table (49 CFR 172.101). It must appear on the shipping paper and package.
UN number: A four-digit identifier assigned to a substance or article, such as UN1203 for gasoline. The UN prefix is used internationally.
NA number: A four-digit identifier starting with NA used for certain materials in the U.S. and Canada only.
Hazard class and division: The category of danger, from Class 1 explosives to Class 9 miscellaneous. See our overview of hazard classes.
Packing group (PG): A level of danger within a class: PG I is great danger, PG II medium and PG III minor. Read packing groups explained.
n.o.s.: “Not otherwise specified,” used for generic entries that require a technical name.
TIH / PIH: Toxic or poisonous by inhalation materials, which have stricter rules.
Marine pollutant: A substance harmful to aquatic life that carries special marking for sea transport.
Documents
Shipping paper: The document that describes the hazardous material, including UN number, PSN, class, PG, quantity and emergency number. See shipping papers and the ERG.
Shipper’s declaration (DGD): The signed air or sea document certifying correct preparation.
Safety Data Sheet (SDS): A 16-section document from the manufacturer. Section 14 gives transport information.
Emergency response information: Details about hazards, first aid and spill response that must accompany the shipment.
24-hour emergency number: A phone number monitored at all times while the product is in transit.
Emergency Response Guidebook (ERG): A reference used by first responders, keyed by UN number and guide number.
Marking and communication
Label: A diamond-shaped hazard sign on a package.
Marking: Text on a package, such as the PSN, UN number and orientation arrows.
Placard: A larger diamond sign on vehicles or containers. Study the placarding guide.
Segregation: Keeping incompatible materials apart in storage or on a vehicle.
Packaging and quantity terms
UN specification packaging: Packaging tested and marked to UN standards. See UN codes explained.
Limited quantity: Small amounts in inner packaging that qualify for reduced requirements.
Excepted quantity: Very small amounts with further relief, mostly for air and sea.
Reportable quantity (RQ): A threshold of certain substances that triggers special shipping paper entries and release reporting.
Overpack: A container holding already-compliant packages for handling convenience.
Salvage packaging: A container for damaged or leaking packages.
Regulations and organizations
HMR: The Hazardous Materials Regulations, 49 CFR Parts 100-185.
PHMSA: The U.S. agency that writes the hazmat transport rules.
FMCSA: The agency that regulates motor carrier safety.
IATA DGR: Dangerous Goods Regulations for air shipping.
IMDG Code: The international code for ocean transport.
ICAO Technical Instructions: The legal framework behind IATA rules.
CHEMTREC / CANUTEC: Emergency information centers for the U.S. and Canada.
Roles
Shipper: The party that prepares or offers the material for transport.
Carrier: The party that transports it.
Consignee: The receiver.
Hazmat employee: Anyone who affects safety of transport and needs training.
When you need help
Terms are only the start. If you are unsure how to classify a product, talk to the compliance team or browse our FAQ.
Frequently asked questions
What is the difference between a label and a placard?
Labels go on packages; placards go on vehicles, containers or bulk packages.
Where do I find the UN number for my product?
Check Section 14 of the SDS and verify the entry in the Hazardous Materials Table.
Is an SDS the same as a shipping paper?
No. The SDS comes from the manufacturer; the shipping paper is prepared by the shipper for each shipment.