UN3373 Compliance: How to Ship Category B Infectious Substances

The United Nations has split its guidelines for shipping infectious substances (6.2 Toxic and Infectious Substances) into two distinct sub-categories: Category A and Category B.

Category B is known as UN3373 and is described as: ‘an infectious substance which does not meet the criteria for inclusion in Category A.’

Category A is split into two further sub-categories: UN2814 (affecting humans) and UN2900 (affecting animals only) and is described as: ‘an infectious substance which is carried in a form that, when exposure to it occurs, is capable of causing permanent disability, life-threatening or fatal disease in otherwise healthy humans or animals.’

When we talk about UN3373 compliance, we explicitly refer to the label and packaging compliance required to ship Category B substances.

Are you unsure whether your sample is Category A or Category B? Try using our simple UN Class 6.2 Classification chart below.

Class 6.2 Classification Chart


Adherence to UN3373 compliance is overseen by the bodies responsible for the transportation of dangerous goods via road and air: The European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) and The International Air Transport Association (IATA), which supports aviation with global standards for airline safety, security, efficiency, and sustainability. These bodies have separate, relevant guidelines to transport UN3373 infectious goods either by land or air, related specifically to the quality of the packaging used and the labels applied to that packaging. These are known as P650.

What is P650?

If a substance is classified as belonging to UN3373, it must be packed for transport according to guidelines known as Packing Instruction 650 (P650 or PI650). This is a list of requirements covering the quality and construction of the packaging used for transport. P650 is split into guidelines for ADR and IATA, with each having slightly different demands on packaging containing UN3373 infectious substances. Guidelines stipulate:

Packaging must consist of three components:

  1. A leak-proof primary receptacle(s) containing not more than 1 L / 1 kg (multiple primary receptacles must be individually wrapped or separated)
  2. Leak-proof secondary packaging
  3. A rigid outer packaging with one surface having minimum dimensions of 100 x 100 mm.

The packaging must be clearly labelled with the UN3373 diamond and adjacent to it the words: Biological Substance, Category B.

Some airlines prohibit the transport of Category B substances, and these must be consigned as Category A. Check with your airline or freight provider before shipping.

When transporting liquids, there must be sufficient absorbent between the primary and secondary packaging to absorb the entire liquid contents of the primary receptacle(s). Max 4 L per package.

When transporting solids, both the primary receptacle(s) and secondary packaging must be siftproof. Max 4 kg per package.

If you’re not 100% confident with the terms, phrases, and words associated with the sector, we have created this helpful guide to simplify some of the sector jargon you may encounter on this page or any of the pages we’ve linked in this resource.

What is 95kPa?

The pascal (Pa) and kilopascal (kPa) are the most common pressure units worldwide. As outlined by UN3373 Category B IATA guidelines: ‘The primary receptacle or the secondary packaging shall be capable of withstanding, without leakage, an internal pressure of 95 kPa (0.95 bar) in the range of -40 °C to +55 °C (-40 °F to +130 °F).’ Our PathoShield, PathoPak, PathoSeal and PathoPouch sample transport solutions are designed to withstand these pressures, ensuring the safety of your payload in transport.

Browse and purchase our 95kPa bags by clicking the button below.

View 95kPa Bags

UN3373 Label Compliance

We design complete sample transport solutions with the correct UN labelling built into the service; however, we have created a helpful guide if you’d like to inquire specifically about label compliance.

Label Compliance Guide

Intelsius UN3373 Packaging

At Intelsius, we’ve been designing and manufacturing UN3373 compliant packaging for over 20 years. We’re experts in ensuring your samples are shipped adhering to strict label and packaging compliance. To view our full range of UN3373 solutions, visit our dedicated webpage.

UN3373 Packaging

To continue the conversation or inquire further about our range of packaging solutions, get in touch with your local Intelsius branch member.

Get in Touch