Two rulebooks govern most dangerous goods freight. The IMDG Code for sea, published by the International Maritime Organization, and the IATA Dangerous Goods Regulations for air, which implement the ICAO Technical Instructions in a form airlines and forwarders actually use.
Both descend from the UN Model Regulations, so classification is common: a Class 3 flammable liquid is Class 3 in both. Almost everything after classification differs, and air is stricter in nearly every respect.
The editions in force right now
Both changed on the same date, which is unusual and worth noting:
- IMDG Code Amendment 42-24 has been mandatory since 1 January 2026. It was adopted in May 2024 by IMO Resolution MSC.556(108) and could be applied voluntarily from 1 January 2025. It brings more than 60 revisions to the Dangerous Goods List and 11 new UN numbers, including entries for sodium ion batteries and lithium powered vehicles.
- IATA DGR 67th Edition took effect on 1 January 2026.
If you are working from a 2024 manual, some of what it says is wrong. Both books are reissued on a fixed cycle, IMDG every two years and IATA annually, and using a superseded edition is itself a compliance failure.
What the two regimes share
- The nine classes and their divisions. See the nine classes with everyday examples.
- UN numbers and proper shipping names, drawn from the same dangerous goods list.
- Packing groups I, II and III, indicating degree of danger.
- UN performance tested packaging and its certification mark.
- The principle that the shipper classifies, packs, marks, labels and declares, and carries the legal responsibility for all of it.
Where they diverge
Quantity limits
Air imposes strict per-package quantity limits that sea does not, and separate limits for passenger aircraft and cargo aircraft. A quantity that is routine in a sea container may be several times the maximum permitted in a single air package.
Outright prohibitions
A number of substances are forbidden by air entirely and move by sea without difficulty. Lithium ion and lithium metal batteries shipped on their own, UN 3480 and UN 3090, are forbidden on passenger aircraft and travel on cargo aircraft only. See shipping lithium batteries.
State of charge
Air restricts the charge level of lithium batteries. From 1 January 2026 the 30 percent state of charge limit that already applied to batteries shipped alone became mandatory for batteries packed with equipment (UN 3481) where cells exceed 2.7 Wh, and for vehicles powered by lithium ion or sodium ion batteries. Sea has no equivalent requirement.
Stowage and segregation
Sea has an elaborate segregation regime, because a container ship carries thousands of parcels for weeks. Four segregation terms translate into minimum distances, and stowage categories decide on deck or under deck. See segregation and stowage at sea. Air handles this through simpler loading rules and the notification to captain.
Documentation
Sea uses a Dangerous Goods Declaration, usually combined with a container packing certificate. Air uses the Shipper's Declaration for Dangerous Goods, which additionally requires the aircraft type limitation and the packing instruction number. Air also requires the NOTOC, telling the crew what is aboard. See the dangerous goods declaration.
Marine pollutants
A sea and inland waterway concept only. A product that must carry the marine pollutant mark by sea may be completely unregulated by air. See marine pollutants and UN numbers.
Reduced regimes
Both codes provide relief for small quantities through Limited Quantities and Excepted Quantities, with different thresholds and different marks, and air is more restrictive on both. See limited and excepted quantities.
Practical sequence for a shipper
- Get the safety data sheet and read section 14. Do not classify from the product name.
- Decide the mode early, because it may decide whether the shipment is possible at all.
- Check the entry in the edition in force, not in last year's book.
- Use UN specification packaging where required, within its certified limits.
- Have a currently trained person prepare and sign the declaration. Training expires.
- Tell the forwarder at quotation stage, not at collection. Dangerous goods change the routing, the vessel or flight, the cut-off and the price.
- Expect refusal to be possible. Some carriers decline some classes outright, and most LCL consolidators decline dangerous goods altogether.
General guidance. Classification and compliance are the shipper legal responsibility and depend on the specific substance, quantity, packaging, mode and route. Work from the current IMDG Code or IATA DGR.
