What Is Dry Ice / Carbon Dioxide Solid Marking?

Dry Ice / Carbon Dioxide Solid Marking A dangerous-goods package marking used to communicate the regulatory information represented by 'Dry Ice / Carbon Dioxide Solid Marking', subject to the applicable mode and regulations.

First: the marking identifies packages that contain solid carbon dioxide (commonly called dry ice) so handlers, carriers, and regulators know how to treat the shipment. The marking signals that the package contains a Class 9 miscellaneous dangerous good (when applicable), and — depending on mode — usually must show the UN number and the net mass of dry ice. The goal is safety: dry ice sublimates to carbon dioxide gas which can displace oxygen in enclosed spaces and build pressure in sealed containers; correct marking helps reduce exposure, mis-stowage, and carriage mistakes.

What The Marking Typically Includes

Although precise format varies by regulation and transport mode, most authorities require some combination of the following elements on the outer package:

• UN Number And Proper Shipping Name: Often shown as "UN 1845" with the name "Carbon dioxide, solid" or the accepted shorthand "Dry ice."
• Net Weight: The net mass of dry ice in the package (expressed in kilograms) so handlers and flight crews can assess ventilation and stowage risks.
• Class Or Handling Label: A Class 9 miscellaneous label or the dry ice handling label required by air regulations; placement and size follow specific rules.

Why The Marking Matters

Dry ice is not flammable, but it presents two principal hazards: oxygen displacement (as it sublimates to CO2 gas) and pressure build-up in airtight packages. Marking allows workers to identify these hazards at a glance, choose appropriate ventilation and stowage, and apply acceptance restrictions such as maximum gross/net amounts per package or per transport unit. For air transport the marking also triggers special acceptance checks and documentation because aircraft cabins and cargo holds are sensitive to gas release and pressure changes.

How Requirements Vary By Mode

Regulatory frameworks differ by transport mode:

• Air: ICAO/IATA rules are the strictest. Packages must display the UN number and proper shipping name, the net weight of dry ice in kilograms, and the specified label. Shippers must also complete dangerous goods declarations or ship under specific limited-quantity provisions when allowed.
• Ground (U.S.): The federal hazardous materials regulations (49 CFR) provide marking and packaging rules, usually requiring the UN number and a net quantity marking, and applying limits for non-bulk shipments.
• Mail/Parcel: Postal authorities and parcel carriers add their own requirements and acceptance policies; some allow dry ice only under specific conditions and labeling formats.

Who Is Responsible

Responsibility falls primarily on the shipper and packer. They must classify the substance correctly, apply the required marking and labels, provide any required shipper's declarations, and verify packaging integrity and ventilation. Carriers and accepting agents must confirm markings and may refuse acceptance if markings or documentation are incorrect or missing.

Practical Example

Shipping a refrigerated food sample by air: the outer box would be marked with the UN number and proper shipping name (for example, "UN 1845, Carbon dioxide, solid" or "UN 1845, Dry ice" depending on the carrier), and the net weight of dry ice (e.g., "Net: 4.0 kg"). The package would carry the required Class 9 or dry ice handling label, and the shipper would complete the dangerous goods declaration or use the appropriate limited quantity provision if eligible.

Common Mistakes To Avoid

• Label Omission: Leaving off the UN number or net weight — a frequent cause of refusal by carriers.
• Wrong Units: Using pounds instead of kilograms for air carriage; many rules mandate kilograms.
• Sealed Containers: Failing to provide proper venting or pressure relief; dry ice requires policies to avoid pressure buildup.

In short, the Dry Ice / Carbon Dioxide Solid Marking tells handlers and regulators that dry ice is present, quantifies how much is in the package, and signals the hazard class — enabling the safe acceptance, stowage, and transport of shipments containing solid carbon dioxide.