If multiple primary receptacles are placed in a single secondary packaging, they must be either individually wrapped or separated so as to prevent contact between them.
The primary receptacle or the secondary packaging must be capable of withstanding, without leakage, an internal pressure producing a pressure differential of not less than 95 kPa (13.8 lbs/in2) because the package may be placed into an unpressurized storage compartment in a cargo aircraft. This must be verified when choosing packaging for shipping either category A or category B substances by aircraft. It is also recommended if shipping by ground. An evacuated blood collection tube that has remained unopened qualifies as a 95 kPa container.
The smallest surface of the outer packaging must be at least 100 mm X 100mm (4 inches x 4 inches).
Other dangerous goods must not be packed in the same packaging as Division 6.2 infectious substances unless they are necessary for preservation of the specimen (e.g., formaldehyde). A quantity of 30 mL or less of formaldehyde or other dangerous goods included in hazard Classes 3, 8, or 9 (flammable liquids such as alcohol; corrosives such as acids or bases; or miscellaneous hazardous materials) may be packed in each primary receptacle containing infectious substances. A quantity greater than 30 mL will require appropriate hazard labels on the package.