What Is a UN Number? 

A UN Number is a four-digit numeric identifier assigned to hazardous materials and dangerous goods for safe transportation worldwide. Often called the “UN hazardous materials number,” it provides a standardized way to classify substances like chemicals, gases, and explosives, ensuring everyone—from shippers to first responders—speaks the same language. 

The UN number meaning extends beyond mere labeling; it’s critical for transport safety, regulatory compliance, packaging requirements, Safety Data Sheets (SDSs), and emergency response. During shipping, it appears on placards, labels, and documents, enabling rapid hazard identification. In SDSs, it populates Section 14 (Transport Information), linking workplace safety to logistics. 

For example, UN 1203 identifies gasoline, a flammable liquid that demands specific handling to prevent fires or explosions. Without accurate UN numbers, mishaps like spills or derailments could escalate into disasters. This guide unpacks everything EHS pros and logistics teams need to know. 

UN Number Decoded 

  • What Does a UN Number Really Mean? 

“UN Number” stands for United Nations Number, originating from the United Nations Committee of Experts on the Transport of Dangerous Goods and on the Globally Harmonized System of Classification and Labelling of Chemicals (UNCETDG). Established in the 1950s under the UN’s Model Regulations, it created a universal system to harmonize hazardous materials transport amid growing global trade. 

  • The core purpose is standardization 

Before UN numbers, countries used disparate codes, leading to confusion, accidents, and trade barriers. Today, over 190 nations adopt them via modal regulations like ADR (road), IMDG (sea), IATA (air), and DOT (US road/rail). A UN number uniquely identifies a substance or category, dictating hazard class, packing, and labeling. 

  • Key distinction 

UN numbers (prefixed “UN”) are global, while NA numbers (North American) are DOT-specific for US/Canada substances without international equivalents, like NA1993 for certain flammable liquids. NA numbers follow similar four-digit formats but aren’t interchangeable—using NA1993 instead of UN1201 (gasoline) could violate international regs. EHS teams must verify: UN for global shipments, NA for domestic North America only. 

This system has slashed transport incidents by 50% since implementation, per UN data, proving its life-saving value. 

Structure of a UN Number 

UN Numbers are concise four-digit codes ranging from UN0001 to UN3600+, maintained in the UN Model Regulations’ Dangerous Goods List. Assigned by the UNECE (UN Economic Commission for Europe), they pinpoint specific substances or generic groups. 

Specific substances get unique numbers: UN2796 for sodium hydroxide (caustic soda solution) or UN2789 for copper-based pesticides. Generic categories use “n.o.s.” (not otherwise specified) entries, like UN1993 for flammable liquids, n.o.s., covering unlisted flammables such as custom solvent blends. “N.o.s.” acts as a catch-all for mixtures or less-defined hazards, requiring shippers to specify components. 

UN numbers interlink with core elements: 

  • Proper Shipping Name (PSN): Descriptive title, e.g., UN1203 is “Gasoline.” 
  • Hazard Class: 1–9 divisions (e.g., Class 3 for flammables). 
  • Packing Group (PG): I (great danger), II (medium), III (minor). 

Together, they form the foundation: UN1203, Acetone, 3, PG II. This quartet ensures precise risk communication. Numbers aren’t random—early ranges (0004–0350) cover explosives, mid-ranges flammables/toxics, higher for miscellany. Updates occur biennially via UN amendments, so compliance software is essential. 

Logistics pros: always cross-reference the full entry, as one number can span classes with qualifiers. 

 

Why UN Numbers Are Important 

UN Numbers drive safety and efficiency across hazardous materials handling. Their standardized format enables instant recognition, reducing human error in high-stakes scenarios. 

  1. Transport Safety

UN numbers appear on orange placards (100mm+), labels, shipping papers, and packages. In accidents, firefighters spot UN1203 on a tanker and know it’s gasoline—evacuate 150m, use foam. Without it, delays prove fatal. 

  1. Regulatory Compliance

Mandatory under DOT 49 CFR, ADR, IMDG, IATA. Non-compliance triggers fines ($80,000+ per violation in US) or shipment halts. EHS teams use them for audits, proving adherence. 

  1. Emergency Response

First responders consult the ERG (Emergency Response Guidebook), indexed by UN number. UN1830 (sulfuric acid)? Guide 137: neutralize spills, protect skin. Apps like CHEMTREC integrate UN lookups for real-time advice. 

  1. Supply Chain & Logistics

Facilitates customs (e.g., EU TARIC codes), segregation (no Class 1 explosives near Class 5 oxidizers), and inventory. WMS/ERP systems flag incompatibilities, optimizing routes and cutting costs 20–30%. 

In sum, UN numbers save lives, ensure compliance, and streamline $1T+ annual hazmat trade. 

 

Where UN Numbers Are Used 

UN Numbers permeate hazmat workflows, from factory to destination. 

  • Vehicle Placards and Tankers: 4×4-inch orange panels on trucks/trailers display “UN1203” for gasoline loads, visible 50m away. 
  • Shipping Documents and Bills of Lading: Airwaybills, manifests list “UN1090, ACETONE, 3, PG II,” certifying compliance. 
  • SDS Section 14 (Transport Information): Digital/paper SDSs detail UN number, PSN, class—vital for EHS training. 
  • Container Labels: Drums/barrels bear diamond labels with UN number in black text. 
  • ERP, WMS, and Logistics Systems: CloudSDS or SAP integrates UN data for auto-placard generation, segregation alerts. 

Example: A chemical distributor ships UN2789 pesticides via IMDG—container label, bill of lading, and SDS all reference it, syncing with port scanners. 

UN Number vs Other Identification Codes 

Distinguishing UN Numbers from similar codes prevents costly errors. 

  • UN vs NA Number 

UN is global (UN0001–UN3600); NA is North American (NA001–NA9998) for DOT-exclusive items like NA3082 for environment hazards, liquid, n.o.s. Some overlap (UN1201=NA1201 gasoline), but NA only for US/Canada road/rail—using NA abroad violates IATA/IMDG. 

  • UN vs CAS Number 

CAS (Chemical Abstracts Service) is a unique registry (e.g., 67-64-1 for acetone) for chemical identity, used in SDS Sections 1–3 for lab/R&D. UN focuses on transport risk—acetone is UN1090 (Class 3), regardless of CAS. 

  • UN vs GHS Pictograms 

GHS (UN’s workplace system) uses skull/flame icons for health/flame hazards on SDS/labels. UN numbers denote transport classes (e.g., UN1075 LPG, Class 2.1)—GHS is a static workplace, UN dynamic for shipping. 

Code  Purpose  Example  Scope 
UN Number  Global shipping  UN1203 (Gasoline)  Global 
NA Number  Domestic NA hazmat  NA1993 (Flammable liq.)  US/Canada only 
CAS Number  Chemical composition  8006-61-9 (Gasoline)  Scientific/SDS 
GHS Pictogram  Workplace hazards  Flame symbol  OSHA/GHS labels 

How to Find a UN Number 

Locating UN numbers is straightforward for compliance. 

  • SDS Section 14: Primary source—lists UN number, PSN, class, PG for the product. 
  • UN Dangerous Goods List: Free in UN Model Regulations (unece.org)—searchable PDF by substance name. 
  • Supplier Documentation and Shipping Databases: Vendor SDS libraries, CAMEO Chemicals (noaa.gov), or paid tools like CHEMTREC/CloudSDS. 

Pro tip: For mixtures, use n.o.s. entries or consult classifiers. Apps like Hazmat Tool or ERG app provide mobile lookups. Always verify biennial updates. 

UN Number and Hazard Classes 

Every UN number ties to one of nine hazard classes (plus divisions), dictating placards and handling. Classes reflect primary dangers: 

UN Number  Proper Shipping Name  Hazard Class/Division  Placard Symbol 
UN1090  Acetone  3 (Flammable Liquid)  Flame 
UN1830  Sulfuric Acid  8 (Corrosive)  Corrosive 
UN1075  Petroleum Gases, Liquefied  2.1 (Flammable Gas)  Flame outline 
UN3082  Environmentally Hazardous Substance, Liquid, N.O.S.  9 (Miscellaneous)  Misc. diamond 

Class 1: Explosives (1.1–1.6); Class 2: Gases (2.1 flammable, 2.2 non-flammable, 2.3 toxic); Class 3: Flammables; Class 4: Flammable solids/spont combust/dangerous when wet; Class 5: Oxidizers/organics; Class 6: Toxics/infectious; Class 7: Radioactive; Class 8: Corrosives; Class 9: Others. 

This mapping ensures uniform response—e.g., UN1203 triggers Class 3 protocols globally. 

 

Packing Groups and UN Numbers 

Packing Groups (PG I–III) refine UN number risk levels, influencing packaging rigor. 

  • PG I (Great Danger): Highest risk (e.g., UN1093 acetone, high flashpoint pure); strictest tests, lowest quantities. 
  • PG II (Medium Danger): Standard (e.g., UN1203 gasoline); moderate packaging. 
  • PG III (Low Danger): Minor (e.g., UN1993 flammable liquid, PG III); relaxed limits. 

PG affects: inner packagings (steel drums for I, plastics for III), quantity caps (air: PG I max 1L vs III 220L), and labels (add PG Roman numeral). DOT/IMDG tables specify per UN entry—misassignment risks leaks or fines. 

EHS tip: Test via lab (flash point, corrosivity) for mixtures. 

 

Legal & Regulatory Requirements for UN Numbers 

UN Numbers are legally binding across modalities. 

  • DOT (US, 49 CFR 172): Required on shipping papers, placards (>1,000lbs), labels. E.g., 172.604 mandates UN on outer packages. 
  • ADR (Europe, road/rail): UN on transport documents, orange plates. 
  • IMDG (Sea, IMO): Container DG manifest with UN; stowage per IMDG 4.1. 
  • IATA (Air): Air waybill, NOTOC (Notification to Captain). 

Mandatory placements: papers (“UN1090, ACETONE, 3, II”), placards (UN in words/numbers), containers (>5L labels). 

Penalties: DOT $91,866/violation (2024); EU €30,000+; seizure. Cases like 2023 IMDG fine ($500k) for missing UN on acid shipment underscore enforcement. Annual training (DOT 172.704) covers this—audit your systems. 

 

Common Mistakes with UN Numbers 

Avoid these pitfalls to prevent disruptions. 

  • Wrong UN for Mixtures: Picking specific (UN1090 acetone) for blends; use n.o.s. (UN1993) with qualifiers. 
  • Confusing UN/NA: NA1993 on IATA shipment rejected at airport. 
  • Outdated/Generic n.o.s. Misuse: Post-amendment UN changes ignored; vague n.o.s. without tech name fails DOT. 
  • Missing on Documents/Placards: Bills sans UN halt customs; unplacarded tanker causes ER delays. 
  • Incorrect PG: Assigning PG II to PG I corrosive breaches quantity limits. 

Fix: Train via ERG, use digital validators like CloudSDS. Audits catch 70% errors pre-shipment. 

 

Real-World Example Scenarios (Mini Case Studies) 

Case 1: Transport Delay: 2022, US chemical firm shipped solvent blend as UN1090 (acetone); DOT inspector flagged wrong n.o.s. (UN1993), delaying 3 days, $50k costs. 

Case 2: Emergency Failure: 2019 tanker crash in EU labeled UN1202 (diesel) but contained UN1203 (gasoline). Responders used wrong ERG guides, worsening fire; €2M fines, injuries. 

Case 3: Customs Rejection: Asia importer used NA3082 for IMDG sea shipment; port rejected for non-UN, $100k demurrage, re-export. 

Lessons: Verify SDS Section 14, train logistics. 

 

UN Numbers in SDS and Digital Safety Systems 

SDS Section 14 mandates UN number, PSN, class, PG—bridging EHS to transport. Digital platforms like CloudSDS auto-populate from databases, integrating with ERP (SAP), WMS for placard gen/segregation. QR codes on eSDS scan to ERG data; AI tools predict UN for mixtures. In LMS, role-based training simulates UN scenarios. Future: blockchain for immutable UN tracking.