DGR 7.2 — Hazard Class & Subsidiary Risk Labels (Specifications & Placement Rules)

Hazard Class & Subsidiary Risk Labels (Specifications & Placement Rules)

Hazard labelling is the primary visual method used in international air transport to communicate the specific chemical and physical hazard risks posed by dangerous goods. Under IATA DGR Section 7.2, hazard labels are divided into two functional categories: primary hazard labels (representing the dominant risk of the substance) and subsidiary risk labels (representing secondary or tertiary risks). All hazard labels must adhere to precise geometric, color, and placement specifications to guarantee immediate recognition by airport ramp agents, cabin crew, and emergency response teams.

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Technical Specifications for Hazard Labels

Every hazard label applied to an air cargo package must conform strictly to international ISO standards and IATA specifications regarding dimensions, border lines, symbols, and text formatting.

          +-----------------------------------+ 
          |                 /\                |
          |                /  \               |
          |               /    \              |
          |              / SYMBOL \           |
          |             /          \          |
          |            |<--- 5mm --->|        |
          |             \          /          |
          |              \        /           |
          |               \ CLASS/            |
          |                \ NUM /            |
          |                 \  /              |
          |                  \/               |
          +-----------------------------------+
          Standard Dimensions: 100 mm x 100 mm
          Inner Line: 5 mm parallel inside edge

1. Shape and Dimensions

• Standard Size: Hazard labels must be square set at a 45° angle (diamond-shaped) with minimum dimensions of 100 mm × 100 mm.
• Reduced Size Allowance: On small packagings or gas cylinders where a 100 mm × 100 mm label cannot fit, dimensions may be reduced to 50 mm × 50 mm, provided all graphics, border lines, and class numbers remain clearly legible and proportional.
• Border Line: A solid line must run parallel to the outer edge of the label, positioned 5 mm inside the perimeter.

2. Primary Hazard Labels vs. Subsidiary Risk Labels

• Primary Hazard Label: Displays the official hazard symbol in the top half and the hazard class or division number in the lower apex (bottom corner). For example, a Class 3 Flammable Liquid label features a flame symbol at the top and the number "3" at the bottom.
• Subsidiary Risk Label: Displays the exact same symbol and background color scheme as the primary label, but under standard IATA DGR rules, it MUST NOT display the class or division number in the bottom corner. This prevents ground handlers from confusing the secondary risk with the primary class rating.
• State Variation Exception: Certain country variations (such as United States Department of Transportation / US DOT rules under 49 CFR) permit or require the class number to be displayed on subsidiary risk labels. However, standard IATA DGR international shipments omit the class number on subsidiary labels unless dictated by State variation.

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Label Placement Rules & Proximity Guidelines

The placement of hazard labels on a dangerous goods package is governed by rigid proximity guidelines to ensure that all crucial hazard warnings can be viewed simultaneously without rotating the container.

$\text{Proximity Rule: Label Surface} = \text{Proper Shipping Name Surface}$

Mandatory Placement Rules

1. Same Surface Rule: Primary hazard labels, subsidiary risk labels, the Proper Shipping Name, and the UN/ID number marking MUST all be located on the same physical surface of the package.
2. Proximity to PSN: Labels must be affixed immediately adjacent to the Proper Shipping Name marking. The DGR sets no numeric separation distance — the test is that the labels and the shipping name are on the same surface and can be read together without turning the package.
3. Side-by-Side Application: When a consignment requires both a primary hazard label and one or more subsidiary risk labels, the labels must be positioned next to each other (separated by no more than a few millimeters) on the same package face.
4. No Overlapping or Folding: Labels must never be folded over package corners or edges, affixed across closures or seams, or covered by adhesive tape, shipping pouches, or overpack straps.
5. Cylinders and Irregular Shapes: On non-cylindrical or small packages where space is restricted, labels may be attached via a durable tag securely fastened to the container.

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Background Contrast & Boundary Requirements

To ensure that hazard labels remain instantly recognizable regardless of the packaging material, IATA DGR Section 7.2 imposes visual contrast requirements:

• Contrasting Background: Labels must be affixed to a surface of contrasting color (e.g., a bright yellow Class 5.1 Oxidizer label on a brown corrugated cardboard box).
• Boundary Line Requirement: If a hazard label is applied to a background color that matches or closely resembles the background of the label (such as a black label applied to a dark carbon-fiber drum), the label must feature a solid or dotted outer boundary line surrounding the entire diamond perimeter to define its edges.

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Summary of Hazard Label Classes & Features