Need to know: the nine classes of dangerous goods
With our refreshed Cathay Dangerous Goods solution, we expertly fly all nine classes of DG – learn what they are
03 Sep 2025

For an industry that prides itself on safety, it might seem counterintuitive that aviation should permit dangerous goods on board aircraft. It is possible, but shippers and forwarders need to consult the IATA Dangerous Goods Regulations (DGR) to do so safely.

This tome-like guide outlines nine classes of dangerous goods (DG); Cathay Cargo is one of the few carriers to accept shipments from them all – though not every sub-category. Such shipments must be booked under the refreshed Cathay Dangerous Goods solution, which is designed to handle them properly.

“From a carrier point of view, most of what we are doing is checking packaging, marking and labelling prior to acceptance, keeping it in segregated storage facilities and then handling it with care, loading it appropriately and away from other types of shipment to further minimise risk on board,” says Joey Lee, Cargo Customer Solutions Manager.

To explore the work of the Cathay Dangerous Goods solution, we look at the nine classes and some of the shipments listed in them.

Class 1: Explosives

Definition: This class of DG covers substances or items that have the ability to rapidly conflagrate or detonate through chemical reaction. Goods could include fireworks, fuse igniters and detonators.

Commonly shipped: Given their nature, these are not common shipments for air cargo or Cathay Cargo.

Notes: “Class 1 dangerous goods have very stringent regulations for air carriage – understandably,” says Lee. “They cannot be mixed with any other class of DG.”

Class 2: Gases

Definition: This class refers to substances which are either completely gaseous at room temperature (approximately 20°C) or turn to vapour when warmed (50°C). It encompasses compressed gases, liquefied gases, dissolved gases, refrigerated liquefied gases, and articles charged with gas, such as aerosols.

Commonly shipped: Butane, helium, nitrogen, carbon dioxide, cryogenic liquids, gas turbine engines.

Notes: One of the more specialist shipments is liquid helium – not for an endless supply of party balloons, but for cooling medical MRI scanners. “The superconducting magnets in these scanners need to be kept very cold, so liquid gases such as helium are used to keep them as close to absolute zero as possible to function properly to produce high-quality images,” says Lee.

Class 3: Flammable liquids

Definition: This class refers to liquids or mixtures that release flammable vapours and are able to ignite at a variety of temperature ranges.

Commonly shipped: Adhesives, paints, alcohols, perfume products, fuels, pesticides.

Notes: This is one of the more popular DG categories, with products ranging from the industrial to bespoke consumer goods such as fragrances. “Paints are probably the most common of these, but we also move a lot of perfume,” says Lee. “We recently shipped quite a lot from Hong Kong to the US for a client launching a new fragrance brand.”

Class 4: Flammable solids; substances liable to spontaneous combustion; substances which, in contact with water emit flammable gases

Definition: Flammable solids are substances that are readily combustible; they may heat or cause a fire through friction (such as when being moved), or by reacting with air or water.

Commonly shipped: Alkali metals (potassium, sodium), metal powders, firelighters, matches, sulphur.

Notes: Because of their nature, these are not frequent travellers with Cathay Cargo. “One of the commonly shipped Class 4 commodities is tantalum powder, an element used in smartphone capacitors and medical equipment. ship,” says Lee.

Class 5: Oxidising substances and organic peroxides

Definition: Oxidisers are defined as substances which may cause a fire or burning, usually by releasing oxygen during a chemical reaction.

Commonly shipped: Ammonium nitrate fertilisers, nitrates, bleaches, hardener for fibreglass manufactured goods.

Notes: These substances are more common than might be supposed; although some look industrial, bleaches and related materials also appear in cosmetics.

Class 6: Toxic or infectious substances

Definition: Toxic substances are those liable to cause serious harm if swallowed, inhaled or touched. Infectious substances are those which are known or highly likely to contain pathogens.

Commonly shipped: Biological samples/specimens such as blood, tissue, viruses, bacteria; chemical substances.

Notes: At one end of the scale, this class includes nicotine compounds found in alternative smoking products; at the other, it includes raw materials used in medical research. “We ship a lot of medical materials for medical research and development that fall outside of our Cathay Pharma solution,” says Lee.

Class 7: Radioactive materials

Definition: In the DGR, radioactive materials are those that contain a certain concentration of unstable atoms which, as they break down, release radiation.

Commonly shipped: Radioactive ores and medical isotopes.

Notes: “The iconic shipments in this class are cancer treatments that have a radioactive component,” says Lee. “We often have shipments from Italy and other parts of Europe of these critical and time-sensitive treatments going to hospitals across Asia.”

Class 8: Corrosives

Definition: Corrosives are substances which degrade or disintegrate other materials upon contact.

Commonly shipped: Acids, acid solutions, battery fluid.

Notes: These products rely on strict compliance for packaging, as they can damage metal surfaces – like the inside of cargo holds – if they leak. “We ship quite a lot of nitric acid,” saysLee. “It has a lot of industrial uses but one of the more specialist ones is in semiconductor manufacturing, for cleaning and etching chips and wafers.”

Class 9: Miscellaneous dangerous substances and articles, including environmentally hazardous substances

Definition: Miscellaneous DG are substances and articles which present a transportation hazard not covered by other classes. This class could include environmentally hazardous substances, items that are transported at elevated temperatures, genetically modified organisms, magnetised materials and aviation regulated substances.

Commonly shipped: Dry ice, polymeric beads used in packing materials, lithium batteries, battery powered equipment and vehicles, fuel-cell engines, internal combustion engines, vehicles, car air-bag modules.

Notes: This is a broad category taking in multiple applications, from expandable packing materials that are flammable, to dry ice, which is used to chill temperature-sensitive shipments such as perishables. “There are limits to how much dry ice can be carried on each aircraft type,” says Assistant Manager Dangerous Goods Fiona Choy. “And the residual quantity of fuel within engines means that vehicles are also classed as dangerous goods.”

As for lithium-ion batteries, this type of shipment is growing in air cargo, fuelled by e-commerce. You can learn more about it here .

 

Related articles

  1. Our Business

    From sea to air with our new sales and solutions expert

    We catch up with new Head of Cargo Global Sales and Customer Solutions Toby Griffiths
    Read moreOpen in new window
  2. Our Business

    Need to know: the nine classes of dangerous goods

    With our refreshed Cathay Dangerous Goods solution, we expertly fly all nine classes of DG – learn what they are
    Read moreOpen in new window
  3. Our Business

    Cargo Connect brings digital efficiency to frontline teams worldwide

    The global roll-out of the app will enable ramp teams across the network to deliver better service
    Read moreOpen in new window
  4. Our Business

    How Cathay Cargo’s new VR CAVE is enhancing training

    More immersive than learning in a classroom, safer than learning on the job, virtual training is a step into the future
    Read moreOpen in new window

Cookies settings


Essential cookies are necessary for the website to function and cannot be switched off. They are usually only set in response to service requests, such as setting your privacy preferences, logging in, or filling in forms. You can set your browser to block or alert you about these cookies, but then some parts of our site will not work. These cookies do not store any personally identifiable information.

Experience & personalization cookies

These cookies enable our website to provide enhanced functionality and personalization. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies, some of the content in our website will not be customised for you.

Advertising cookies

Advertising cookies collect information about the browsing habits associated with your device and deliver targeted ads. They are also used by third parties providing their services on this website. Third parties provide these services in return for recognising that you have visited a certain website.

Measurement & analytics cookies

We use analytic cookies to analyse how our visitors use our website. This allows us to provide a high quality experience by customising our offerings and identifying and fixing any issues that arise. We may also use these cookies to highlight articles or site services that we think may interest you, based on your usage of the website.

Feedback