If dry ice is used as a refrigerant, it must be placed outside the secondary container. Interior supports must be provided to secure the secondary packaging in the original position after the dry ice has dissipated. The packaging must be designed and constructed to permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture the packaging. A styrofoam-lined box is considered a vented outer container.
Labels and markings for air transport of dry ice- Class 9 label, as shown on the right (miscellaneous hazardous materials)—this is an IATA requirement.
- Proper shipping name (either "Dry ice" or "Carbon dioxide, solid)
- UN designation: UN 1845 (IATA requirement)
- The net quantity (weight) of the dry ice
Quantity limits for dry ice in outer packaging - USPS (category B or exempt substance): 5.5 lbs
- IATA/DOT (air): 200 kg/441 lbs
Requirement when transporting under DOT regulations
- Make advanced arrangements with the carrier if the quantity of dry ice per package exceeds 2.5 kg (5.5 lbs).
