Dry ice — solid carbon dioxide — is the default coolant for shipping frozen or chilled biological samples, reagents, and other temperature-sensitive lab materials. It is also, on its own, a regulated dangerous good in every transport mode: air, ground, and ocean. This guide covers the rules that apply specifically to dry ice as a shipped material — classification, packaging, marking and labeling, and how the requirements differ by mode of transport. For the broader dangerous-goods framework dry ice sits inside (the nine UN hazard classes, the Shipper’s Declaration, and IATA training requirements), see CASRAI’s IATA Dangerous Goods Regulations guide; for coolant selection and temperature-range guidance, see Cold-Chain Shipping Requirements for Biological Reagents.
Why Dry Ice Is a Regulated Material
Dry ice is assigned UN 1845, proper shipping name Carbon Dioxide, Solid, and is classified as a Class 9 (Miscellaneous Dangerous Goods) hazardous material under the UN Model Regulations, the IATA Dangerous Goods Regulations (DGR), the ICAO Technical Instructions, and the US DOT Hazardous Materials Regulations (49 CFR Parts 171-180). It earns that classification because of a single physical property: dry ice does not melt, it sublimates directly from solid to carbon dioxide gas. In an enclosed space — a sealed cooler, a cargo hold, a walk-in cold room, a vehicle cabin, or even an elevator — that gas can build up enough pressure to rupture packaging, and enough concentration to displace breathable oxygen and create an asphyxiation hazard. Regulators treat it as a dangerous good specifically to control that risk, not because the material itself is toxic or flammable.
Because Class 9 doesn’t read as obviously hazardous the way a corrosive or flammable liquid does, dry ice is one of the two materials (alongside lithium batteries) that most often catches lab shippers off guard — a package can look like routine cold-chain packaging and still be a fully regulated dangerous goods shipment once dry ice is inside it above a small quantity.
Packaging Requirements: Why Dry Ice Packages Must Vent
The single non-negotiable packaging rule across every transport mode is that dry ice packaging must not be hermetically sealed. Outer packaging has to allow the carbon dioxide gas produced by sublimation to escape as the shipment travels. Wrapping a dry-ice shipper in extra tape to make it ‘more secure,’ or using an airtight cooler not designed for dry ice, defeats this requirement and creates the exact pressure-buildup risk the regulation exists to prevent. Packaging intended for dry ice shipment is specifically designed and tested to vent safely while still containing the dry ice and its contents; substituting an arbitrary insulated box is a compliance failure even if nothing ruptures in transit.
For air shipments, dry ice packaging must meet IATA’s numbered Packing Instruction 954 (see below). For ground and ocean shipments, the venting principle is the same, but it’s expressed through DOT and IMDG Code packaging requirements rather than an IATA packing instruction number.
Packing Instruction 954, in Practice
Packing Instruction (PI) 954 is the IATA DGR’s numbered packing instruction for UN 1845 dry ice shipped by air. It specifies the type of outer packaging permitted, requires that the packaging design permit release of carbon dioxide gas to prevent a pressure buildup, and sets a maximum net quantity of dry ice allowed per package. That quantity limit is not the same for every shipment — it differs between cargo-aircraft-only service and combination/passenger aircraft, and it is subject to change between DGR editions and to individual carrier ‘operator variations’ layered on top of the base IATA requirement (see the IATA DGR guide for how operator variations work generally). Because of that, don’t rely on a saved reference sheet or a prior shipment’s quantity as your current limit — confirm the figure in the DGR edition currently in effect, or directly with the airline or freight forwarder handling the shipment, every time you’re packing a shipment that’s close to a threshold.
Marking and Labeling Requirements
A package containing dry ice must be marked, at minimum, with:
- The proper shipping name — Carbon Dioxide, Solid or Dry Ice — and the UN number, UN 1845
- The net quantity of dry ice in the package, expressed in kilograms, as it will be at the time the shipment is handed to the carrier (not the quantity originally packed, if some has already sublimated before departure)
- The Class 9 miscellaneous dangerous goods hazard label, once the quantity exceeds the small threshold that some carriers treat as marking-only
Whether a given shipment needs a full Class 9 hazard label and a Shipper’s Declaration for Dangerous Goods, or qualifies for a simpler marking-only treatment because the dry ice is present solely as a refrigerant for non-regulated contents, is itself a classification decision that depends on quantity and the current DGR provisions — it is not a default assumption based on the package ‘feeling small.’ The person preparing the shipment needs to actually check this each time, not assume based on how past shipments were handled.
Air (IATA/ICAO) vs. Ground (DOT) vs. Ocean (IMDG)
The UN 1845 / Class 9 classification is consistent across modes, but the specific rulebook — and how much relief a small quantity gets — differs:
- Air: Governed by the IATA DGR (built on the ICAO Technical Instructions), with Packing Instruction 954 and the marking/labeling rules above. See CASRAI’s IATA Dangerous Goods Regulations guide for the full classify-pack-mark-declare workflow this sits inside.
- Ground (US domestic): Governed by the DOT Hazardous Materials Regulations, 49 CFR Parts 171-180. Dry ice used solely as a refrigerant for other, non-hazardous contents generally receives somewhat relaxed treatment on ground shipments compared to a fully regulated hazardous material shipped for its own sake — but relaxed is not the same as unregulated: it is still UN 1845, still Class 9, and package marking requirements typically still apply. Confirm current thresholds and conditions directly against 49 CFR rather than assuming a shipment is exempt because it’s going by truck instead of air.
- Ocean: Governed by the IMDG Code (International Maritime Dangerous Goods Code, administered under the International Maritime Organization), which applies its own stowage, segregation, and ventilation provisions for sea containers carrying UN 1845 alongside the same basic classification.
A shipment that combines dry ice with another regulated material — a Category B biological specimen packed in dry ice, for example — is regulated under both sets of requirements simultaneously; meeting the dry ice rules doesn’t satisfy the biological-substance rules or vice versa. See CASRAI’s Category A vs. Category B classification guide for that side of a combined shipment.
Common Compliance Mistakes Labs Make With Dry Ice
- Treating dry ice as ‘just packaging’ rather than a regulated Class 9 dangerous good — it’s a UN-numbered hazardous material in its own right, independent of whatever it’s cooling.
- Sealing or overwrapping packaging in a way that blocks venting — the most common physical compliance failure, and a genuine safety hazard, not just a paperwork issue.
- Marking the quantity packed rather than the quantity present at handoff — sublimation means these can differ meaningfully over a multi-hour prep-to-pickup window.
- Assuming ground shipments are unregulated — they’re subject to relief compared to air in some circumstances, not exempt.
- Not training the staff who actually pack dry-ice shipments — under the IATA DGR, anyone who classifies, packages, marks, labels, or documents a dangerous goods shipment needs current function-specific training, regardless of whether they sit in a shipping department. See CASRAI’s Hazmat Shipping Training and Certification guide.
Frequently Asked Questions
What packing instruction covers dry ice shipments by air?
IATA Packing Instruction 954 governs air shipments of UN 1845 dry ice. It requires packaging that permits carbon dioxide gas to vent and sets a maximum net quantity per package that varies by aircraft type and can change between DGR editions — confirm the current figure rather than relying on a past shipment.
What are the dry ice shipping label requirements?
At minimum, a dry ice package must be marked with the proper shipping name (Carbon Dioxide, Solid, or Dry Ice), the UN number UN 1845, and the net quantity in kilograms. Above the quantity threshold where marking-only treatment no longer applies, the package also needs the Class 9 miscellaneous dangerous goods hazard label.
Is dry ice regulated for ground shipping in the US, or only for air?
Both. Ground shipments fall under the DOT Hazardous Materials Regulations (49 CFR Parts 171-180) as UN 1845, Class 9. Dry ice used purely as a refrigerant may receive somewhat relaxed treatment compared to air shipment, but ground transport is not unregulated — marking requirements in particular typically still apply.
Why does dry ice packaging need to vent instead of being sealed airtight?
Because dry ice sublimates directly into carbon dioxide gas rather than melting. In a sealed package, that gas builds pressure and can rupture the container; in an enclosed space it can also displace breathable oxygen. Packaging designed for dry ice is built to release the gas safely while still containing the shipment.
Does a small amount of dry ice still require a Shipper’s Declaration?
Not always — dry ice used solely as a refrigerant for other, non-regulated contents often qualifies for a simpler marking-only treatment below certain quantities, without a full Shipper’s Declaration for Dangerous Goods. Whether a specific shipment qualifies is a classification decision based on current DGR provisions, not a default assumption based on the package looking small.
