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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

ID Number

Mailability

Required Packaging

General
Marking
Documentation

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.