5.2 Special Markings: Environmentally Hazardous, Elevated Temperature, and Quantity Marks

Special Markings: Environmentally Hazardous, Elevated Temperature, and Quantity Marks

The Environmentally Hazardous Substance (EHS) Mark (ADR 5.2.1.8 & 5.3.6)

Certain chemical substances present little or no acute human toxicity or flammability yet pose devastating hazards to aquatic ecosystems. When spilled into rivers, lakes, or drainage systems, these pollutants cause widespread mortality among fish and aquatic organisms. To warn handlers, drivers, and emergency crews of this specific danger, ADR prescribes the Environmentally Hazardous Substance (EHS) mark.

Symbol and Visual Design

The EHS mark displays a distinctive black graphic depicting a dead tree and dead fish, set against a white or contrasting background.

Application Scope

The EHS mark applies to:

• UN 3077 (Environmentally hazardous substance, solid, n.o.s.) and UN 3082 (Environmentally hazardous substance, liquid, n.o.s.) in Class 9.
• Any substance classified under Classes 1 through 9 that meets the aquatic pollutant criteria of ADR 2.2.9.1.10 (acute aquatic toxicity Category 1 or chronic aquatic toxicity Categories 1 and 2).

Package vs. Vehicle Display Dimensions

• Packages (ADR 5.2.1.8.3): Display a diamond mark measuring at least 100 mm by 100 mm. If the package size requires it, dimensions may be reduced down to 50 mm by 50 mm provided the mark remains clearly visible.
• Tanks and Bulk Containers (ADR 5.3.6): Display an enlarged EHS placard measuring at least 250 mm by 250 mm. On tank-vehicles, it is affixed to both sides and the rear adjacent to hazard placards. On tank-containers, portable tanks, and bulk containers, it must be displayed on all four sides.

The 5 Litre / 5 Kilogram Package Exemption (Special Provision 375)

Under ADR 5.2.1.8.1 and Special Provision 375, dangerous goods meeting the EHS classification that are packed in single packagings or inner packagings of combination packagings containing a net quantity of 5 litres or less for liquids, or 5 kilograms or less for solids, are exempt from the EHS package mark under 5.2.1.8.1. SP 375 separately relieves UN 3077/3082 from other ADR provisions under its packaging conditions; it does not remove an independent flammable or corrosive classification, provided the packaging meets general safety and construction standards (ADR 4.1.1.1, 4.1.1.2, 4.1.1.4 to 4.1.1.8).

Elevated Temperature Substance Mark (ADR 5.3.3)

Certain industrial products must be loaded and transported at intense heat to remain fluid or processable during transit. Common examples include molten bitumen, road asphalt, liquid coal tar, and molten sulfur.

Marking Criteria

Under ADR 5.3.3, the elevated temperature mark is mandatory on tank-vehicles, tank-containers, portable tanks, special vehicles, and bulk containers transporting substances that are loaded or carried:

• In a liquid state at or above 100 °C (e.g., UN 3257 Elevated temperature liquid, n.o.s.).
• In a solid state at or above 240 °C (e.g., UN 3258 Elevated temperature solid, n.o.s.).

The elevated-temperature triangle is a separate warning from the orange plate and hazard placard; it communicates heat, not a new hazard class.

Visual Specifications and Display

• Design: An equilateral triangle with sides of at least 250 mm, framed by a red border and enclosing a red thermometer symbol.
• Placement: Affixed to both sides and the rear of tank-vehicles; affixed to all four sides of tank-containers, portable tanks, and bulk containers.

Operational Hazards for Drivers

Elevated temperature substances introduce severe physical burn hazards (temperatures frequently reach 160 °C to 200 °C). If rain or extinguishing water enters an open tank hatch containing molten bitumen, instant vaporization causes explosive steam expansion and violent boil-overs. Follow the designed closure and venting procedure. Do not obstruct a safety vent or improvise a sealed condition that the equipment is not designed to withstand.

Limited Quantity (LQ) Vehicle Marking (ADR 3.4.13 – 3.4.15)

Dangerous goods packed in small inner receptacles (such as aerosol cans, small paint tins, or retail cleaning products) can be consigned under the Limited Quantity (LQ) framework of ADR Chapter 3.4. At the package level, these items display the 100 x 100 mm diamond mark with black top and bottom points.

Transport Unit Trigger Thresholds (ADR 3.4.13)

While small vans carry LQ goods without external markings, heavy freight combinations must display vehicle markings when exceeding specific weight thresholds:

1. The transport unit has a Maximum Permissible Gross Vehicle Weight (GVW) exceeding 12 tonnes; AND
2. The transport unit carries more than 8 tonnes gross mass of packages bearing the Limited Quantity mark.

Display Requirements

When both criteria are met, the transport unit must display enlarged LQ marks measuring at least 250 mm by 250 mm at the front and rear of the vehicle.

Intermodal Containers and The Orange Plate Exemption

• Containers (ADR 3.4.14): Freight containers carrying more than 8 tonnes gross mass of LQ packages loaded onto transport units exceeding 12 tonnes must display 250 x 250 mm LQ marks on all four sides, and the container marks are required in their own right. If not visible from outside the carrying vehicle, repeat them at the front and rear of the transport unit unless the applicable orange-plate alternative is used.
• Orange Plate Exemption (ADR 3.4.15): If the transport unit is already displaying plain or numbered orange-coloured plates in accordance with ADR 5.3.2 (because it also transports fully regulated dangerous goods), the vehicle is exempt from displaying the LQ mark.

Fumigation and Coolant Warning Marks (ADR Chapter 5.5)

Special warning signs are required under ADR Chapter 5.5 to protect drivers, warehouse workers, and customs inspectors from toxic or asphyxiating atmospheres inside enclosed cargo transport units.

1. Fumigated Cargo Transport Units (ADR 5.5.2)

Cargo containers or vehicles treated with toxic gases (such as phosphine or methyl bromide) to eradicate agricultural pests or wood-boring insects must display the Fumigation Warning Mark:

• Design: A rectangular sign at least 400 mm wide by 300 mm high, displaying a black skull and crossbones on a white background with bold text stating: DANGER - THIS UNIT IS UNDER FUMIGATION APPLIED ON [Date] [Time] - DO NOT ENTER.
• Placement: Affixed at each access point (cargo doors) so that anyone attempting to enter is immediately warned.
• Safety Protocol: The unit must not be entered until it has been completely ventilated and gas detectors verify that fumigant concentrations have fallen below occupational exposure limits.

2. Coolant and Conditioning Warning Mark (ADR 5.5.3)

Where the 5.5.3 risk assessment and ventilation conditions require marking, cargo spaces containing dangerous goods used as refrigerants or conditioners—most commonly dry ice / solid carbon dioxide (UN 1845) or liquid nitrogen (UN 1977):

• Design: Use the prescribed asphyxiation warning model, at least 150 mm wide by 250 mm high. It includes the warning symbol, the word WARNING and the name of the coolant/conditioner; it is not an invented red-frame sentence label.
• Placement: Displayed at each door or access point.
• Hazards: Sublimating dry ice or boiling liquid nitrogen displaces breathable oxygen, creating an invisible, odourless, and lethal asphyxiation hazard within seconds of opening vehicle doors.

Summary: ADR Special Markings Reference Table

Source check: 17 October 2026 — ADR 2025, English text published by the Slovak Ministry of Transport, 5.2.1.8, 5.3.3, 5.3.6 and 5.5.