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If you handle dangerous goods, the first decision that keeps people safe—and shipments moving—is correct classification. Get it wrong and you risk rejected cargo, regulatory penalties, and harm to people and the environment. Yet the rules can feel fragmented: nine hazard classes, divisions and packing groups, different labels and placards, and mode rules for air, sea, road and rail. Add lithium nuances and limited/excepted quantities, and even experienced teams can hesitate. The challenge is turning the UN Model Regulations into day‑to‑day decisions that stand up to audits and inspections.
This practical guide from Logicom Hub brings clarity. We summarise each of the nine dangerous goods hazard classes—highlighting what’s covered, key divisions, hazard labels/placards, typical examples with UN numbers, and any differences across ADR (road), IMDG (sea), IATA/ICAO (air) and RID (rail). Use it as a reference to check classifications, select the right marks and documentation, and brief your team. Let’s step through the classes so you can ship compliantly and confidently.
1. Logicom Hub: training for dangerous goods classes and labels
Our courses turn rules into actions you can apply on the job. We blend regulation, real scenarios and coaching so your team classifies, marks and ships right first time.
What it covers
We train across the nine dangerous goods hazard classes, from fundamentals to advanced topics. Options include Lithium Batteries, Infectious Substances and Dry Ice, Radioactive by Air, Limited/Excepted Quantities, and DGSA preparation.
Divisions and packing groups (if applicable)
We clarify how UN divisions and packing groups drive packaging, documentation and limits. You’ll practise selecting the right classification data and translating it into compliant packs.
Hazard labels and placards
We teach the correct hazard labels and placards by class and division, including subsidiary risks. You’ll apply size, placement and marking rules for full, limited and excepted quantities.
Common examples and UN numbers
Training uses everyday examples with their typical UN numbers to build confidence. Think aerosols, petrol, dry ice, lithium batteries, clinical waste and more.
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
We show how requirements change by mode and how to stay aligned. Expect practical drills on the IATA/ICAO air Declaration, sea/road Dangerous Goods Note, and mode-specific quantity rules under ADR, IMDG and RID.
2. Class 1 — explosives (divisions 1.1–1.6)
Within the dangerous goods hazard classes, Class 1 covers explosive substances and articles that can detonate, deflagrate or rapidly decompose, causing blast, projection and/or fire hazards. Includes manufactured items (articles) and pure or mixture explosives.
Divisions and packing groups (if applicable)
Packing groups don’t apply; risk is set by divisions:
- 1.1: mass explosion hazard
- 1.2: projection hazard only
- 1.3: fire hazard, minor blast/projection
- 1.4: no significant hazard
- 1.5: very insensitive, mass explosion
- 1.6: extremely insensitive, no mass explosion
Hazard labels and placards
Use the Class 1 Explosive label; placards show the division (1.1–1.6).
Common examples and UN numbers
Common examples: fireworks, flares and igniters. Check the UN Dangerous Goods List for the exact UN number and compatibility group for each article.
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
Class 1 faces the most restrictions. Many entries are forbidden or heavily limited by air (IATA/ICAO). ADR, IMDG and RID impose strict segregation and quantity limits.
3. Class 2 — gases (divisions 2.1, 2.2, 2.3)
Class 2 in the dangerous goods hazard classes covers gases under pressure: compressed, liquefied or refrigerated. Hazards include flammability, toxicity, oxidising effects, asphyxiation and sudden pressure release.
What it covers
It includes pure gases, mixtures, aerosols and gas‑charged articles. Risk increases with leaks, heat, impact, poor ventilation or incompatible materials.
Divisions and packing groups (if applicable)
Packing groups don’t apply; divisions define the primary hazard. Use the UN list to confirm the correct assignment.
- 2.1 Flammable gases: e.g., butane.
- 2.2 Non-flammable, non-toxic gases (incl. oxidising/asphyxiant): e.g., nitrogen, helium, carbon dioxide, oxygen.
- 2.3 Toxic gases: e.g., chlorine, phosgene.
Hazard labels and placards
Use the Class 2 hazard label showing the division number (2.1, 2.2 or 2.3). Add any subsidiary risk label where the entry requires it.
Common examples and UN numbers
Typical consignments include aerosols and fire extinguishers, fuel gases such as butane, inert gases like nitrogen, helium and carbon dioxide, oxygen, and toxic gases such as chlorine and phosgene. Always confirm the proper shipping name and UN number in the UN Dangerous Goods List.
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
IATA/ICAO impose tighter quantity and packaging limits for gases, with additional restrictions for Division 2.3. ADR, IMDG and RID set marking, placarding, stowage and segregation rules for cylinders, aerosols and tank loads.
4. Class 3 — flammable liquids
Within the dangerous goods hazard classes, Class 3 covers liquids and liquid mixtures that can ignite readily, creating fire and vapour hazards during handling and transport. Many are everyday fuels and solvents, so correct classification and labelling are critical to safe loading, stowage and emergency response.
What it covers
Flammable liquids include pure liquids, mixtures and solutions with sufficient flammability to be a transport hazard. They are common in consumer products and industrial supplies.
Divisions and packing groups (if applicable)
There are no divisions for Class 3. Packing groups I–III apply; use the UN Dangerous Goods List to confirm the correct proper shipping name and packing group for your substance or mixture.
Hazard labels and placards
Use the Class 3 Flammable Liquid hazard label. For vehicles/containers, apply the Class 3 placard. Add any required subsidiary risk label where specified.
Common examples and UN numbers
Typical consignments include:
- Petrol/lighter fluid: common fuels and ignitable liquids.
- Acetone and solvents: e.g., nail polish remover.
- Perfumery products: alcohol-based liquids with flammability.
Always confirm the proper shipping name and UN number in the UN Dangerous Goods List.
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
Air transport (IATA/ICAO) applies tighter quantity and packaging limits, with additional restrictions on passenger aircraft. ADR, IMDG and RID prescribe package/vehicle marking, placarding, stowage and segregation; check limited/excepted quantity allowances by mode.
5. Class 4 — flammable solids; substances liable to spontaneous combustion; dangerous when wet (4.1, 4.2, 4.3)
Class 4 in the dangerous goods hazard classes covers solids and certain reactive materials that ignite easily, self‑heat to the point of fire, or react with water to release flammable gases. Typical risks are rapid burning, intense heat, toxic combustion products and violent reactions if exposed to moisture, contamination or heat sources during transport.
What it covers
It includes flammable solids, self‑reactive substances and solid desensitised explosives (4.1), substances liable to spontaneous combustion (4.2), and substances which, in contact with water, emit flammable gases (4.3). Always verify the proper shipping name and conditions in the UN Dangerous Goods List.
Divisions and packing groups (if applicable)
Many entries use Packing Groups I–III; confirm in the UN list for your material.
- 4.1 Flammable solids/self‑reactive/solid desensitised explosives: burn readily; may decompose vigorously.
- 4.2 Spontaneously combustible: self‑heating; may ignite on contact with air.
- 4.3 Dangerous when wet: react with water to release flammable gas.
Hazard labels and placards
Apply the Class 4 hazard label showing the correct division (4.1, 4.2 or 4.3). Add any subsidiary risk label if assigned, and use corresponding placards on vehicles/containers.
Common examples and UN numbers
Use the UN Dangerous Goods List to confirm UN numbers and packing instructions. Typical shipments include:
- Metal powders (easily ignited fine solids)
- Sodium batteries (certain designs treated as flammable solids)
- Seed cake (oil‑bearing seeds) with residual oil/self‑heating risk
- Solid desensitised explosives (treated to reduce sensitivity)
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
Air transport imposes stringent quantity and packaging limits, especially for 4.2 and 4.3. IMDG and ADR/RID require segregation from water and incompatible goods, “keep dry” stowage where specified, and clear marking/placarding; limited/excepted quantity allowances vary by mode.
6. Class 5 — oxidising substances and organic peroxides (5.1, 5.2)
Class 5 in the dangerous goods hazard classes covers materials that can cause or contribute to combustion, and highly reactive peroxides that may ignite or explode. They often intensify fire and are difficult to extinguish if mismanaged in transport.
What it covers
Includes oxidising substances that release oxygen to support burning (5.1) and organic peroxides that are thermally unstable and may decompose violently (5.2). Always verify the proper shipping name in the UN Dangerous Goods List.
Divisions and packing groups (if applicable)
Many entries use Packing Groups I–III; confirm in the UN list.
- 5.1 Oxidising substances: promote combustion; react with combustibles.
- 5.2 Organic peroxides: inherently reactive; may be explosive or burn rapidly.
Hazard labels and placards
Apply the Class 5.1 or 5.2 hazard label as assigned; add any subsidiary risk label where required. Use corresponding placards on vehicles/containers.
Common examples and UN numbers
Confirm UN numbers and packing instructions in the UN Dangerous Goods List.
- Hydrogen peroxide (oxidising liquid)
- Lead nitrate (oxidising salt)
- Organic peroxides (various formulations as assigned)
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
IATA/ICAO impose strict quantity/packaging limits, particularly for 5.2. ADR, IMDG and RID require segregation from combustibles and incompatible materials, with clear marking, placarding and stowage controls.
7. Class 6 — toxic and infectious substances (6.1, 6.2)
Class 6 in the dangerous goods hazard classes covers materials that can seriously harm health through exposure, and substances containing pathogens that can cause disease. Correct classification, labelling and packaging are critical because small leaks or poor handling can have severe consequences.
What it covers
This class includes:
- 6.1 Toxic substances: materials liable to cause death or serious injury by ingestion, inhalation or skin contact.
- 6.2 Infectious substances: goods containing micro‑organisms that can cause infectious disease in humans or animals (pathogens), plus certain contaminated wastes.
Divisions and packing groups (if applicable)
Class 6 is split into 6.1 (toxic) and 6.2 (infectious). Where packing groups apply (e.g., many 6.1 entries), use the UN Dangerous Goods List to confirm the correct assignment and corresponding packaging requirements.
Hazard labels and placards
Apply the Class 6.1 Toxic hazard label for poisonous substances and the Class 6.2 Infectious Substance label for pathogen risks. Use subsidiary risk labels where assigned and the matching placards on vehicles/containers. Some 6.1 entries carry a “Poison Inhalation Hazard” warning where specified.
Common examples and UN numbers
Typical shipments include toxic chemicals and laboratory reagents (6.1), and healthcare consignments such as medical/clinical waste containing pathogens (6.2). Always confirm the proper shipping name and UN number in the UN Dangerous Goods List. Note: dry ice used to refrigerate specimens is Class 9, not Class 6.
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
Air transport (IATA/ICAO) imposes strict quantity limits and packaging instructions for both 6.1 and 6.2, with additional restrictions on passenger aircraft. ADR, IMDG and RID set detailed rules for segregation, stowage, marking/placarding and documentation; check mode‑specific limited/excepted quantity allowances and emergency response provisions.
8. Class 7 — radioactive material
Within the dangerous goods hazard classes, Class 7 covers radioactive material that emits ionising radiation from unstable atoms (radionuclides). The risks are exposure to radiation and contamination if packaging is damaged or mishandled, so accurate classification, robust packaging and clear labelling are essential for every movement.
What it covers
Class 7 includes radioactive substances and articles containing radionuclides used in industry and research. Shipments must control radiation levels and prevent contamination through compliant containment, shielding and handling as prescribed in the transport regulations.
Divisions and packing groups (if applicable)
Packing groups are not used for Class 7. Classification and packaging are assigned by the relevant entry in the UN Dangerous Goods List; always confirm the proper shipping name, activity limits and packaging requirements there.
Hazard labels and placards
Use the Class 7 Radioactive hazard label on packages and the corresponding placard on vehicles/containers. Apply any additional marks and documentation required by the assigned entry.
Common examples and UN numbers
Typical consignments include the following; always confirm the exact proper shipping name and UN number in the UN Dangerous Goods List.
- Smoke detectors: small quantities of radioactive material in consumer or industrial devices
- Yellowcake (uranium concentrate): processed ore containing radionuclides
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
IATA/ICAO impose strict packaging performance, quantity and documentation limits for air, with further restrictions on passenger aircraft. ADR, IMDG and RID set detailed rules for marking, placarding, segregation, stowage and emergency response; check mode‑specific provisions before each shipment.
9. Class 8 — corrosive substances
Class 8 in the dangerous goods hazard classes covers highly reactive materials that chemically degrade other materials and can cause severe injury to living tissue. Spills or leaks can rapidly damage cargo, packaging and equipment, so correct classification, robust packaging and clear labelling are essential for safe carriage and emergency response.
What it covers
Corrosives include liquids and solids that attack surfaces and tissues through chemical action. They are widely used in industry, laboratories and maintenance, and require careful handling to prevent contact, contamination or heat build‑up during transport.
Divisions and packing groups (if applicable)
Class 8 is not subdivided like Classes 4–6. Many entries are assigned Packing Groups I–III to reflect severity; confirm the proper shipping name and packing group for your substance or formulation in the UN Dangerous Goods List before packing.
Hazard labels and placards
Use the Class 8 Corrosive hazard label on packages and the corresponding placard on vehicles/containers. Apply any subsidiary risk label where assigned and ensure size, durability and placement meet the mode rules.
Common examples and UN numbers
Typical consignments include batteries (certain types), chlorides and flux used in industrial processes. Always verify the correct proper shipping name, UN number and packing instructions in the UN Dangerous Goods List for the exact product being shipped.
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
Air (IATA/ICAO) imposes tighter quantity limits and packaging performance standards, especially on passenger aircraft. ADR, IMDG and RID prescribe marking, placarding, segregation from incompatible goods and stowage controls; check any limited/excepted quantity provisions that may apply by mode.
10. Class 9 — miscellaneous dangerous substances and articles (including lithium batteries)
Class 9 gathers miscellaneous dangerous goods that do not fit other classes yet still pose transport risks. Typical hazards include asphyxiation, heat, pressure, reactivity, environmental harm, or magnetic fields—lithium batteries are the most frequently encountered.
What it covers
It includes diverse substances and articles with special transport hazards. These are items hazardous in carriage even when not flammable, toxic or corrosive under other classes, and therefore require specific handling and marks.
Divisions and packing groups (if applicable)
There are no divisions in Class 9. Packing groups are generally not assigned; always confirm any PG and the proper shipping name in the UN Dangerous Goods List.
Hazard labels and placards
Use the Class 9 Miscellaneous hazard label and the corresponding placard for vehicles/containers. For lithium batteries by air, apply the Class 9 label and the lithium battery mark where required by IATA/ICAO.
Common examples and UN numbers
Confirm the exact UN number and proper shipping name in the UN Dangerous Goods List.
- Dry ice used as a refrigerant
- Lithium‑ion and lithium metal batteries (alone or with/in equipment)
- Engines and machinery containing fuel or batteries
- Air bag modules and seat belt pretensioners
- Magnetised material affecting navigation instruments
- Marine pollutants shipped as dangerous goods
Mode-specific notes (ADR, IMDG, IATA/ICAO, RID)
Air transport applies strict, unique restrictions to lithium batteries and dry ice, with specific quantity, packaging and documentation rules. ADR, IMDG and RID prescribe placarding, marine pollutant marking where applicable, segregation and stowage controls; check any limited/excepted quantity allowances by mode.
Put the hazard classes into practice
You’ve got the classes; now turn that into compliant movements. For every consignment, start with the substance/article data, then work down to packaging, marking, documentation and mode rules. Small differences—like a subsidiary risk or a passenger‑aircraft limit—change outcomes, so follow a consistent process.
- Identify the UN entry: proper shipping name and UN number.
- Assign hazards: class, division and, where used, packing group.
- Select packaging/limits: apply ADR/IMDG/IATA/ICAO/RID instructions.
- Mark and communicate: labels, placards, lithium/marine pollutant marks, orientation if needed.
- Document and brief: correct DG declaration/Note and emergency information.
Need a second set of eyes and hands‑on practice? Logicom Hub provides e‑learning, classroom, virtual and in‑house training that bridges regulations to your workflows, plus post‑course support. Train your team to classify, pack and declare with confidence—start here: Logicom Hub.