USPS Packaging Instruction 9A

Dry Ice (Carbon Dioxide Solid)

When dry ice is enclosed in a thick metal or other restricting type of container, a build–up of internal pressure could cause the container to rupture or explode. Dry ice is permitted to be sent in domestic mail when it is used as a refrigerant to cool the contents of a mailable hazardous or nonhazardous material, provided that all applicable requirements in 349 are met.

Proper Shipping Name

• Carbon Dioxide Solid or Dry Ice.

ID Number

• UN1845.

Mailability

• International Mail: Prohibited.
• Domestic Mail: Permitted with restriction via air or surface transportation.

Required Packaging

General

• Packages containing dry ice must be packed in containers that permit the release of carbon dioxide gas and conform to 49 CFR 173.217 and 175.10(a)(10). If a fiberboard box is used, enough insulation is necessary to prevent condensation and wetting of the mailing carton.
• For air transportation, each mailpiece may not contain more than 5 pounds of dry ice.
• For surface transportation, a mailpiece may contain more than 5 pounds of dry ice.

Marking

• Each mailpiece must be clearly marked on the address side with the name of the contents being cooled (such as frozen medical specimens, steaks) and the net weight of the dry ice.
• For air transportation, each mailpiece must bear a Class 9 DOT miscellaneous hazardous material warning label and must be clearly marked “Carbon Dioxide Solid, UN1845” Or “Dry Ice, UN1845.”
• For surface transportation, each mailpiece must be clearly marked “Surface Only” or “Surface Mail Only” and “Carbon Dioxide Solid, UN1845” or “Dry Ice, UN1845.”

Documentation

• For air transportation, a properly completed shipper‘s declaration for dangerous goods must be prepared in triplicate and affixed to the outside of the mailpiece.

Note: A shipper’s declaration and a Class 9 DOT warning label are not required for dry ice sent via domestic surface mail. Mailpieces containing dry ice that are prepared for surface transportation must not, under any circumstances, be routed via air transportation.