UN 1845 Marking: U.S. Transport Rules For Air, Road, And Rail

UN 1845 Marking The UN identification marking for carbon dioxide, solid, commonly known as dry ice.

Regulatory frameworks set the minimum content and format for the UN 1845 Marking and related shipment documentation. In the United States, domestic and international transport of dry ice is governed by modal regulations that incorporate the UN Model Regulations: the Federal hazardous materials rules (49 CFR) for road and rail, and the ICAO/IATA rules for air. Carriers and shippers must follow the applicable mode-specific requirements for marking, labeling, and declaring dry ice.

Air Transport Requirements

Air rules are the most prescriptive because the aircraft environment concentrates off-gassed carbon dioxide. Common requirements under ICAO and IATA that affect marking include:

• Proper Shipping Name and UN Number: Packages must be marked with "UN 1845" and the proper shipping name (e.g., "Carbon dioxide, solid (dry ice)").
• Net Weight: The net mass of dry ice in each package must be indicated on the outer packaging and on the air waybill or shipper's declaration for dangerous goods.
• Handling Labels: A Class 9 or specific dry ice handling label is typically required; the handling label assists ground staff with stowage and ventilation decisions.

Ground (Road & Rail) Requirements

Road and rail transport in the U.S. are regulated under Title 49 (49 CFR). Relevant expectations for markings are:

• UN Identification: The UN number and proper shipping name on packages are standard practice and required for many shipments.
• Placarding: Large loads may require vehicle placards which display the appropriate hazard class or UN number per CFR thresholds.
• Documentation: Drivers and rail personnel must be able to access transport emergency information and know the shipper's declaration when required.

Who Is Legally Responsible

Under U.S. hazardous materials law the shipper is responsible for proper classification, packaging, marking, labeling, and documentation before offering the shipment to a carrier. Carriers also have responsibilities to refuse nonconforming shipments and to properly stow and transport declared dangerous goods.

Enforcement And Penalties

Regulatory agencies (e.g., DOT/PHMSA in the U.S.) may inspect shipments and issue civil penalties for missing or incorrect markings, improper documentation, or unsafe packaging. Even when violations do not result in enforcement action, carriers commonly return or delay shipments that do not meet marking requirements.

Practical Compliance Checklist

• Package Marking: Mark packages clearly with "UN 1845" and the appropriate proper shipping name.
• Net Weight: For air transport, include the net mass of dry ice per package on the outside of the package and on transport documents.
• Paperwork: Complete and retain the required shipper's declaration or dangerous goods statements when applicable.
• Carrier Procedures: Confirm any carrier-specific marking or label requirements before tendering the load.

When Exceptions Apply

Some small-quantity exemptions exist in modal regulations for limited amounts of dry ice, often with simplified marking or documentation. These exceptions are narrow and mode-specific; shippers should not assume a small package is automatically exempt without checking the relevant regulation or carrier policy.

In short, the UN 1845 Marking must match the requirements of the transport mode being used: air transport typically requires the most detailed markings and net weight declarations, and road/rail follow the 49 CFR structure. The shipper bears initial responsibility for correct application to avoid delays, refusals, or enforcement actions.