Author: Beccy Ricketts, ADR Express Ltd and BADGP Committee member

“To start my swim this winter, I had to break the ice…”

There’s nothing quite like the sharp sting of 1.7 °C water biting at your skin as you push aside a crust of ice to begin an open-water swim. This winter, that was my entry into the lake — a silent, black surface rimmed with frozen plates that cracked as I waded forward.

Cold-water swimmers learn quickly that winter water demands respect, preparation, and an understanding of the environment. Surprisingly, this mindset aligns directly with the world of dangerous goods compliance, especially when working with something as deceptively simple as dry ice (UN1845). Dry ice appears simple: an odourless, flavourless, non- flammable, residue-free refrigerant – but in transport it behaves in ways that demand careful management. As it warms, it doesn’t melt but sublimates, turning straight into carbon dioxide gas. This is where the risks begin. Even a relatively small amount can release enough gas to significantly reduce oxygen levels in an enclosed space, creating an invisible asphyxiation hazard. Add to that its extreme temperature of around −78 °C, which can cause instant cold burns, and the potential for pressure build-up if the gas is trapped inside sealed packaging, and it’s clear why dry ice is classified as a dangerous substance.

Across all modes of transport, dry ice carries the same classification: UN1845 – Carbon dioxide, solid (dry ice), Class 9, but the way these rules apply varies depending on whether it’s travelling by road, sea, or air. On the road under ADR, dry ice is not fully regulated in the same way as many dangerous goods, yet several critical requirements still exist. Packaging must be suitable for very low temperatures and must allow gas to escape so pressure cannot build up. Any vehicle or container used to carry goods cooled by dry ice must be well ventilated unless it’s separated from the driver or already mechanically temperature controlled. Packages must be clearly marked with “DRY ICE”, “CARBON DIOXIDE, SOLID”, or the proper shipping name of the cooled goods followed by “AS COOLANT” or “AS CONDITIONER”. And if the load space isn’t fully ventilated before transport, the transport document must include the UN number, the proper shipping name, and a note indicating that the dry ice is being used as a coolant or conditioner. Even when ADR doesn’t impose full dangerous goods obligations, the focus remains firmly on preventing
unnoticed gas accumulation.

At sea, the IMDG Code follows much of the same logic. Dry ice cooled consignments must be packed to withstand the cold, marked correctly, and carried in spaces with appropriate ventilation. The maritime environment brings its own challenges, particularly around confined cargo hold atmospheres, so good airflow and clear identification are essential.

Air transport, however, treats dry ice with the highest level of scrutiny. Under IATA Packing Instruction 954, packaging must be strong enough to handle very low temperatures while also allowing gas to escape safely. Shippers must coordinate with the airline, particularly if the carrier has its own limitations on dry ice quantities. When no Shipper’s Declaration is required, the Air Waybill must still show the number of packages, the proper shipping name, the UN number, and importantly – the net weight of dry ice in each package. Each individual package must also be marked with this net weight, and any overpacks must show the total amount inside. This level of detail makes sense: a sealed aircraft cargo environment provides very little margin for error if carbon dioxide begins to accumulate.

For something so widely used temperature-sensitive materials from pharmaceuticals and medical samples to fresh food and dry ice can easily be taken for granted. Yet its behaviour is unique enough that each transport mode has built safety procedures into its regulations. When used properly, dry ice is incredibly effective: clean, efficient, and reliable. But its ability to rapidly generate large volumes of gas means it must always be handled with respect. Clear marking, appropriate packaging, good ventilation, and accurate documentation ensure that it stays both useful and safe.

Both winter swimming and dangerous goods handling rely on the same principles:

• Know the environment
• Respect the hazard
• Prepare properly
• Act with discipline

Safety isn’t about eliminating risk – it’s about understanding it well enough to move through it confidently.