IATA Biological Packaging Guide: PI650, PI620, PI954

Shipping biological substances by air means working within three packing instructions that most life sciences shippers encounter at some point: PI650, PI620, and PI954. Each governs a different substance and a different level of risk.

PI650 covers UN3373, the classification most diagnostic and research samples fall under. PI620 covers Category A infectious substances, materials that can cause serious or fatal disease. PI954 covers the dry ice that keeps many of these shipments at the right temperature in transit.

Knowing which instruction applies, and applying it correctly, is the difference between a shipment that clears customs and one that gets rejected at the tarmac.

PI650: Category B Biological Substances (UN3373)

PI650 governs UN3373, the designation for biological substances that contain pathogens but are not capable of causing life-threatening disease in otherwise healthy people or animals. Full classification criteria are set out in the IATA Dangerous Goods Regulations.

This is the classification most life sciences shippers work with day to day: routine blood draws, diagnostic swabs, and tissue samples destined for non-infectious testing. For a closer look at how to determine whether a sample qualifies as UN3373, see Shipping UN3373 Samples Safely and Legally.

Packaging requires a triple-layer system. The inner and secondary receptacles must both be leak-proof, and the outer packaging must be rigid enough to withstand handling. Absorbent material goes between the inner and secondary layers to contain any leakage.

Inner receptacles must withstand a 95 kPa pressure differential, and the outer package must carry the UN3373 diamond mark along with the words "Biological Substance, Category B." Quantity limits apply per package: 1 liter per primary receptacle and 4 liters total per outer package.

No Shipper's Declaration for Dangerous Goods is required for UN3373 shipments, which makes PI650 the most operationally straightforward of the three instructions. The packaging standards, though, are not optional.

PI620: Category A Infectious Substances (UN2814, UN2900)

PI620 governs Category A infectious substances, materials known to cause permanent disability, life-threatening illness, or death. UN2814 applies to substances affecting humans, UN2900 to those affecting animals. Ebola samples, rabies cultures, and pure cultures of certain tuberculosis strains fall under this classification.

The packaging structure mirrors PI650's triple-layer approach, but the outer packaging must pass IATA-specified drop, puncture, and stacking performance tests before use. Inner receptacles still require 95 kPa pressure resistance.

Packages must display the UN2814 or UN2900 marking along with the appropriate class 6 infectious substance label. Unlike PI650, PI620 shipments require a Shipper's Declaration for Dangerous Goods on every shipment.

Quantity limits are tighter on passenger aircraft, typically capped at 50 mL or 50 g per package, with higher limits permitted on cargo-only aircraft. The added documentation and testing reflect the higher public health risk these substances carry.

PI954: Dry Ice as a Refrigerant (UN1845)

PI954 applies to solid carbon dioxide, UN1845, used to keep biological shipments at the correct temperature during transit.

Dry ice is itself a regulated hazard: as it sublimates, it releases carbon dioxide gas that can build dangerous pressure in a sealed container or displace oxygen in a confined space, a risk the U.S. Occupational Safety and Health Administration also addresses in its guidance on confined space hazards.

Packaging must allow gas to vent safely while remaining rigid enough to survive handling. The outer package must show the UN1845 marking, the net weight of dry ice inside, and the words "Carbon Dioxide, Solid." The airwaybill must separately declare the dry ice content and net weight.

Quantity limits depend on aircraft type and the specific operator's approval, which is why a dry ice quantity that clears on one carrier's flight may not clear on another's. PI954 rarely stands alone. It is most often applied alongside PI650 or PI620, since dry ice is the default refrigerant for both diagnostic and infectious biological shipments.

Comparing the Three Instructions

What Changed Under the 2026 IATA DGR

The 67th Edition of the IATA Dangerous Goods Regulations, effective January 1, 2026, sharpened the general philosophy section to emphasize supply chain safety. It clarifies the responsibilities of every party in the chain, from shipper to ground handler to carrier.

For biological and dry ice shipments, this translates into closer scrutiny of documentation completeness and operator-specific variations at acceptance. Operator variations continue to shift year over year, and some carriers have tightened dry ice quantity approvals beyond the IATA baseline.

Shippers working under PI954 should confirm current operator variations before every shipment rather than assuming last year's approved quantity still applies.

Where Compliance Breaks Down

Most rejected biological shipments trace back to a small set of recurring errors. Mislabeling is the most common: using UN2814 markings on a Category B shipment, or omitting the UN1845 weight declaration on dry ice packaging.

Incomplete documentation follows close behind, particularly missing Shipper's Declarations on PI620 shipments or absent dry ice entries on the airwaybill.

Improper packaging construction is a third recurring issue, such as triple packaging that skips the absorbent layer or outer packaging that has not passed required performance testing.

Staff training gaps compound all of the above. IATA requires role-specific, current dangerous goods training, and personnel working from an outdated DGR edition are a compliance exposure regardless of how careful the packaging looks.

How Mercury Supports Biological Shipments

Mercury manages classification, packaging, and documentation for biological substance shipments across PI650, PI620, and PI954, for life sciences and healthcare organizations moving samples that cannot afford a delay.

Our team verifies UN classification before a shipment leaves the origin facility, catching mislabeling and documentation gaps before they reach the carrier's dock. Shipments that also include battery-powered monitoring equipment carry their own classification rules, covered in Shipping Lithium-Ion Batteries: UN3480 and UN3481.

For shipments combining infectious substances or diagnostic samples with dry ice, Mercury coordinates the specific operator variations that apply to each carrier and route.

Organizations shipping temperature-sensitive biological materials can also review Mercury's specialty cold chain shipping services for validated packaging across the full temperature spectrum. For guidance on classifying your shipment correctly before packaging begins, see Classifying Biological Shipments Safely.

For help with a specific biological shipment or an ongoing program, contact Mercury's team.