Dry ice in carry-on baggage

This responds to your October 12, 2007 letter requesting clarification on transporting dry ice under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask if a package containing dry ice in carry-on baggage must be marked as required in §175.10(a)(10) if it is transferred for transportation in checked baggage.

The answer is yes. When a carry-on bag containing dry ice cannot fit in the cabin and will then be placed in the cargo compartment of an aircraft, it is now considered checked baggage. For checked baggage, the package containing dry ice must be marked with "Dry Ice" or "Carbon dioxide, solid" and the net weight of the dry ice or an indication the net weight is 2.3 kg (5 pounds) or less.