2026-04-12 • GHS Pictograms Editorial Team
Every dangerous good transported by road in Europe must be classified under one of the 9 ADR hazard classes. Each class has its own placard colour, symbol, and documentation requirements under the ADR 2025 agreement.
This guide covers all 9 classes with their divisions, placard descriptions, real-world substance examples, and the closest GHS pictogram equivalents.
👉 Look the number up in the UN number reference: the ADR 2025 row, the 49 CFR 172.101 row and the orange plate, each under its own source.
Looking for GHS hazard classes instead? ADR classes govern the transport of dangerous goods by road, and there are 9 of them. The classification behind labels and safety data sheets is a separate system with 33 classes — see all GHS hazard classes and categories.
ADR Class 1 — Explosives
Placard colour: Orange
Symbol: Exploding bomb
UN divisions: 1.1 through 1.6
Class 1 covers substances and articles that can explode, deflagrate, or cause a pyrotechnic effect. It is divided into 6 divisions based on the type of hazard:
| Division | Description | Example |
|---|---|---|
| 1.1 | Mass explosion hazard | TNT, dynamite |
| 1.2 | Projection hazard, no mass explosion | Ammunition |
| 1.3 | Fire hazard, minor blast | Propellants |
| 1.4 | Minor hazard, no mass explosion | Fireworks (consumer) |
| 1.5 | Very insensitive, mass explosion hazard | Blasting agents |
| 1.6 | Extremely insensitive articles | Military ordnance |
Closest GHS equivalent: GHS01 — Exploding Bomb
⚠️ Class 1 goods require a licensed explosives carrier and specific vehicle approval under ADR. Standard hauliers cannot carry Class 1 without special authorisation.
ADR Class 2 — Gases
Placard colour: Varies by sub-class
Symbol: Gas cylinder
Sub-classes: 2.1 (Flammable), 2.2 (Non-flammable), 2.3 (Toxic)
| Sub-class | Description | Placard colour | Example |
|---|---|---|---|
| 2.1 | Flammable gases | Red | LPG, hydrogen, acetylene |
| 2.2 | Non-flammable, non-toxic gases | Green | Nitrogen, compressed air, CO₂ |
| 2.3 | Toxic gases | White | Chlorine, ammonia, phosgene |
Closest GHS equivalents:
- 2.1 → GHS02 — Flame
- 2.2 → GHS04 — Gas Cylinder
- 2.3 → GHS06 — Skull and Crossbones
Gases under ADR must be transported in UN-approved pressure vessels. The cylinder itself must carry the GHS label; the vehicle carries the ADR placard.
ADR Class 3 — Flammable Liquids
Placard colour: Red
Symbol: Flame
UN number range: UN 1170 – UN 3494 (selected)
Class 3 is one of the most common ADR classes in road transport. It covers liquids with a flash point below 60°C, including fuels, solvents, and many industrial chemicals.
| Flash Point | Packing Group | Example |
|---|---|---|
| Below -18°C | I (High danger) | Diethyl ether (UN 1155) |
| -18°C to 23°C | II (Medium danger) | Acetone (UN 1090), Ethanol (UN 1170) |
| 23°C to 60°C | III (Low danger) | Diesel (UN 1202), White spirit |
Closest GHS equivalent: GHS02 — Flame
Class 3 liquids are typically also classified under GHS as Flammable Liquids Category 1–4 depending on flash point and boiling point.
ADR Class 4 — Flammable Solids
Class 4 is divided into three distinct sub-classes:
Class 4.1 — Flammable Solids
Placard colour: White with red stripes
Solids that are easily ignited and burn vigorously. Includes self-reactive substances and desensitised explosives.
Examples: Sulphur (UN 1350), Naphthalene (UN 1334), Matches (UN 1944)
Class 4.2 — Spontaneously Combustible
Placard colour: White (top) / Red (bottom)
Substances liable to spontaneous heating or ignition on contact with air.
Examples: White phosphorus (UN 1381), Activated carbon (UN 1362)
Class 4.3 — Dangerous When Wet
Placard colour: Blue
Substances that emit flammable gases on contact with water.
Examples: Sodium (UN 1428), Calcium carbide (UN 1402), Lithium (UN 1415)
| Sub-class | Key Trigger | Placard Colour |
|---|---|---|
| 4.1 | Flame / friction | White + red stripes |
| 4.2 | Air contact | White / red split |
| 4.3 | Water contact | Blue |
Closest GHS equivalent for all: GHS02 — Flame
ADR Class 5 — Oxidising Substances and Organic Peroxides
Class 5.1 — Oxidising Substances
Placard colour: Yellow
Symbol: Flame over circle
Substances that may cause or intensify fire by releasing oxygen.
Examples: Hydrogen peroxide >60% (UN 2015), Ammonium nitrate (UN 1942), Potassium permanganate (UN 1490)
Closest GHS equivalent: GHS03 — Flame Over Circle
Class 5.2 — Organic Peroxides
Placard colour: Red (top) / Yellow (bottom)
Thermally unstable substances that can decompose exothermically. Many also require temperature control during transport.
Examples: Dibenzoyl peroxide (UN 3106), Cumene hydroperoxide (UN 3107)
Closest GHS equivalents: GHS02 + GHS03
ADR Class 6 — Toxic and Infectious Substances
Class 6.1 — Toxic Substances
Placard colour: White
Symbol: Skull and crossbones
Substances that can cause death or serious injury on inhalation, skin absorption, or ingestion.
| Packing Group | Oral LD50 (rat) | Example |
|---|---|---|
| I | ≤ 5 mg/kg | Hydrogen cyanide (UN 1051) |
| II | 5–50 mg/kg | Methanol (UN 1230), Phenol (UN 1671) |
| III | 50–300 mg/kg | Chloroform (UN 1888) |
Closest GHS equivalent: GHS06 — Skull and Crossbones
Class 6.2 — Infectious Substances
Placard colour: White
Symbol: Biohazard (ADR-specific, not a GHS pictogram)
Substances known or reasonably expected to contain pathogens.
Examples: Clinical waste (UN 3291), Biological cultures (UN 2814)
ADR Class 6.2 has no direct GHS equivalent — the biohazard symbol is used in ADR but is not part of the GHS pictogram set.
ADR Class 7 — Radioactive Material
Placard colour: White / Yellow
Symbol: Trefoil (radioactivity symbol)
Categories: I-White, II-Yellow, III-Yellow (based on radiation level)
Class 7 is regulated jointly by ADR and the IAEA Transport Regulations (SSR-6). It covers all radioactive materials including medical isotopes, industrial gauges, and nuclear fuel.
GHS equivalent: None. Radioactive hazards are outside the scope of GHS.
Transport of radioactive material requires special training, vehicle approval, and route planning beyond standard ADR requirements.
ADR Class 8 — Corrosive Substances
Placard colour: Black (top) / White (bottom)
Symbol: Corrosion (liquid attacking metal and hand)
Packing groups: I, II, III based on severity
Corrosive substances cause full-thickness destruction of skin tissue on contact, or corrode steel or aluminium at a rate exceeding 6.25 mm/year.
| Packing Group | Skin destruction time | Example |
|---|---|---|
| I | ≤ 3 minutes | Sulphuric acid >51% (UN 1830) |
| II | 3 min – 1 hour | Acetic acid >80% (UN 2789) |
| III | 1–4 hours or metal corrosion | Battery acid (UN 2796) |
Closest GHS equivalent: GHS05 — Corrosion
ADR Class 9 — Miscellaneous Dangerous Substances
Placard colour: White with black stripes (top)
Class 9 is a catch-all for substances that present a hazard during transport but do not fit into Classes 1–8.
| Type | Example | UN Number |
|---|---|---|
| Environmentally hazardous liquids | Polychlorinated biphenyls | UN 2315 |
| Lithium batteries | EV batteries, laptop batteries | UN 3480 / UN 3481 |
| Dry ice | CO₂ solid | UN 1845 |
| Magnetised material | Industrial magnets | UN 2807 |
| Elevated temperature liquids | Molten sulphur | UN 2448 |
Closest GHS equivalent: GHS07 or GHS09 — Environmental Hazard depending on substance
Lithium batteries (Class 9) are among the fastest-growing ADR compliance challenges due to the explosion of EV and electronics transport. Always check the latest ADR 2025 provisions for UN 3480 and UN 3481.
Quick Reference: All 9 ADR Classes
| Class | Name | Placard Colour | GHS Pictogram |
|---|---|---|---|
| 1 | Explosives | Orange | GHS01 |
| 2.1 | Flammable gases | Red | GHS02 |
| 2.2 | Non-flammable gases | Green | GHS04 |
| 2.3 | Toxic gases | White | GHS06 |
| 3 | Flammable liquids | Red | GHS02 |
| 4.1 | Flammable solids | White/red stripes | GHS02 |
| 4.2 | Spontaneously combustible | White/red | GHS02 |
| 4.3 | Dangerous when wet | Blue | GHS02 |
| 5.1 | Oxidising substances | Yellow | GHS03 |
| 5.2 | Organic peroxides | Red/yellow | GHS02 + GHS03 |
| 6.1 | Toxic substances | White | GHS06 |
| 6.2 | Infectious substances | White | None |
| 7 | Radioactive | White/yellow | None |
| 8 | Corrosives | Black/white | GHS05 |
| 9 | Miscellaneous | White/black stripes | GHS07 / GHS09 |
Official Sources
Tools for ADR and GHS Compliance
- 🔍 UN number reference — The ADR and US table entries for a number, side by side and never merged
- 🏷️ GHS Pictogram Library — Download SVG pictograms GHS01–GHS09
- 🧪 Substance Database — Search 4,000+ substances with full GHS classification
This guide is based on ADR 2025 and GHS Revision 10. Always verify classification with the official ADR agreement and your national competent authority.