Last reviewed 18 August 2022

This article looks at the differences in marking and labelling of packages for transport across the modes and identifies the key differences. The article will not cover Class 1, 2, 6.2 or 7 provisions.


The marking and labelling requirements are identified in the various modal regulations. For road, rail and sea they are found in Chapter 5.2 of ADR, RID and International Maritime Dangerous Goods (IMDG). For air transport (IATA) the common user requirements are found in s.7 of the IATA Dangerous Goods Regulations.

Land (“fully regulated”)


The provisions of ADR (Road) and RID (Rail) both require the following marking to be displayed on packages.

  • The UN number, which, as with all modes, is to be preceded by the Latin characters UN in capitals. The sizes of the characters is now defined as being at least 12mm high for packages greater than 30 litres or 30kg net mass. For packages of 30 litres/30kg or less they shall be at least 6mm in height and for packages of 5 litres/5kg or less they shall be of an appropriate size in relation to the package.

  • Where the goods are identified as meeting the requirements of an Environmentally Hazardous Substance (EHS), the EHS mark will be displayed (Figure 1).

    Figure 1: EHS Mark

    The mark is also required to be displayed when the two UN numbers for EHS, ie UN 3077 and UN 3082 respectively, are transported. This mark shall be a minimum of 100 x 100mm; there is an option to reduce the size to suit the size of the package, however it must still be clearly visible. The mark shall be displayed in close proximity to the UN number. The mark is not needed on goods classified with a prime hazard in Classes 1–8, but for those with a supplementary EHS classification when in receptacles not exceeding 5kg/5 litres.

    From 1 January 2015, chemicals intrinsically classifiable as UN 3077/3082 may now be exempt from ADR/RID under Special Provision 375, subject to meeting certain general packaging requirements, when in receptacles (single or inner) containing not more than 5kg/5 litres. Discussions are ongoing to increase this 5kg/litres limit, so in the future Special Provision 375 may be extended.

  • Orientation arrows are required for the following packages: a combination package, where the inner packages contain liquid products; a single package requiring venting or a cryogenic receptacle containing liquefied refrigerated gas (Figure 2). The mark shall be rectangular and of an appropriate size in relation to the package. The arrows can be red or black and should be on a white or contrasting background. The arrows must be displayed on two opposite vertical sides of the package and must be pointing in the correct orientation.

    Figure 2: This way up

For labelling ADR/RID requires the labels identified in column 5 of Table A in Chapter 3.2 (the dangerous goods list). The labels will include the main class and any subsidiary risk label required unless a special provision provides otherwise, ie for some Class 4.1 and 5.2 products.

The labels are the standard UN transport labels and measure 100 x 100mm but, again, can be reduced to accommodate small packages as long as they are clearly visible (Figure 3).

Figure 3: Example of a Class Label


  • For the inner border line, there is now a requirement for a minimum 2mm width line 5mm in from the outer border, even if the label size is reduced (if permitted under ADR/RID).

  • If placed on a non-contrasting background, then there shall also be an outer border line (dotted or continuous).

Where overpack is used that obscures the compliant package marks and labels, for example, dark stretch wrap, ADR/RID also requires the overpack to be marked on the outside with the word OVERPACK and the marks and labels required. This is not required if at least one set of marks and labels of the goods in the overpack are clearly visible.

The word OVERPACK shall be at least 12mm high and in the language of the forwarding country. It should also be written in English, French or German if the language of the forwarding country is not one of these.

For Intermediate Bulk Containers (IBCs) greater than 450 litres, the marks and labels must be shown on two opposite sides.

ADR/RID requires all marks and labels to be able to withstand open weather exposure without a substantial reduction in effectiveness.

ADR/RID also requires that packages which are empty but not cleaned out are marked and labelled the same as if they were full.

Sea (“fully regulated”)

For sea transport under the provisions of the IMDG code, the marking and labelling provisions are the same as ADR/RID, but there are some exceptions as explained below.


Packages for any sea journey (including UK mainland to Isle of Wight) shall also be marked with the Proper Shipping Name (PSN), which will also include the technical name required in accordance with Special Provision 274 or 318, or if the goods have a supplementary Marine Pollutant risk* (exactly same criteria as ADR/RID, just a different term).

The IMDG code also requires the Marine Pollutant mark (exactly the same as the EHS mark required by ADR/RID, as shown in Figure 1 above) to be shown on packages when the product is identified as a marine pollutant.

However, since 1 January 2015, under IMDG Code (rather than by Special Provision 375) these Marine Pollutant requirements are not required when the receptacle does not contain more than 5kg/5 litres (including effective exemption as ADR/RID when the goods are only intrinsically classifiable under UN 3077/3082, subject to compliance with the same general packaging provisions).

* Note: While the Dangerous Goods list in IMDG identifies in the alphabetical listing, a number of products which are deemed to be Marine Pollutants, signified by the letter “P”, all other goods are subject to self-classification.

Air (“fully regulated”)


All packages shall be marked with the proper shipping name and UN number, as per IMDG, however, air always requires that the PSN shall be in English, whereas IMDG Code makes no such requirement.

The International Air Transport Association (IATA) has an additional ID 8000 number and PSN, which is used for consumer commodities and is considered the same as the UN number.

Additional markings include the name and address of both the consignor and consignee. The net weight of dangerous goods should be displayed if there is more than one package in the consignment.

Labelling (“fully regulated”)

IATA identifies several different circumstances where particular labelling is required.

The Cargo Aircraft Only (CAO) label is used when quantities greater than IATA permit on passenger aircraft are consigned and this signifies that the packages shall only travel on cargo aircraft (Figure 4).

Figure 4

Magnetised materials can affect the navigational equipment on aircraft and there is a label to identify such products which are carried under UN 2807. This label replaces the Class 9 label (Figure 5).

Figure 5

For Self-reactive Substances of Division 4.1 and Organic Peroxides of Division 5.2 a “Keep away from heat” label is required (Figure 6).

Figure 6

Limited and Excepted Quantity packages

Limited Quantity packages

The marking requirements for Limited Quantity (LQ) goods are similar for both road/rail and sea but differ considerably for air transport.

For ADR/RID and IMDG there is no requirement to show either the PSN or UN number or any class labels on the packages. The marks and labels mentioned above are replaced by the LQ mark, a diamond shaped mark measuring 100 x 100mm with the top and bottom elements in black and the central element in either white or a suitable contrasting colour (Figure 7).

Figure 7: Surface-only LQ Mark

Orientation arrows should also be displayed on two opposite vertical sides of the package if the inner packages contain any liquids.

For air transport the marking is significantly more detailed. The mark has the “Y” in the central section indicating that a LQ packing instruction (these are prefixed with the letter “Y”) has been complied with. Furthermore, all the standard details such as the UN number, PSN and any others must also be shown in addition to the LQ mark.

Excepted Quantities

For excepted quantities the only mark required is the excepted quantity mark (Figure 8). This mark is in the form of a square measuring a minimum of 100mm and shows the “E” in a circle and the primary class or division. In addition the mark shows the name of the shipper or consignee if they are not shown elsewhere on the package.

Lithium batteries UN 3090, UN 3091, UN 3480 and UN 3481 not meeting the provisions of SP 188

The following new label, Model No. 9A fis required for all lithium cells or batteries of UN numbers 3090, 3091, 3480 and 3481 not meeting the provisions of SP 188.


As can be seen, the differences between the different modes of transport for marking and labelling can be significant. Those responsible for the marking and labelling of packages need to understand these key differences and are required by all modes to have received suitable training for the role. The regulations are complex and if in doubt seek advice from your company’s Dangerous Goods Safety Advisor (DGSA).