HAZMAT Classification

Class 1 – Explosives

Class 1 is comprised of:

a. Explosive substances (a substance which is not itself an explosive but which can form an explosive atmosphere of gas, vapour or dust is not included in Class 1), except those that are too dangerous to transport or those where the predominant hazard is appropriate to another class;

b. Explosive articles, except devices containing explosive substances in such quantity or such a character that their inadvertent or accidental ignition or initiation during transport shall not cause any effect external to the device either by projection, fire, smoke, heat or loud noise; and

c. Substances and articles not mentioned under (a) or (b) which are manufactured with a view to producing a practical, explosive or pyrotechnic effect.

Class 1 is further divided into six divisions:

Division 1.1 – Substances and articles which have a mass explosion hazard (a mass explosion is one which affects almost the entire load virtually instantaneously). Division 1.2– Substances and articles which have a projection hazard but not a mass explosion hazard.
Division 1.3–Substances and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard.This division comprises substances and articles which:

  1. Give rise to considerable radiant heat; or
  2. Burn one after another, producing minor blast or projection effects or both
Division 1.4 – Substances and articles which present no significant hazard. This division comprises substances and articles which present only a small hazard in the event of ignition or initiation during transport. The effects are largely confined to the package and no projection of fragments of appreciable size or range is to be expected. An external fire shall not cause virtually instantaneous explosions of almost the entire contents of the package.
Division 1.5 – Very insensitive substances which have a mass explosion hazard. This division comprises substances and blasting agents which have a mass explosion hazard but are so insensitive that there is very little probability of initiation or of transition from burning to detonation under normal conditions or transport. Division 1.6– Extremely insensitive articles which do not have a mass explosion hazard. This division comprises articles which contain only extremely insensitive detonating substances and which demonstrate a negligible probability of accidental initiation or propagation.

Class 2 – Gases

Division 2.1 – Flammable Gases: Gases which at 20°C and a standard pressure of 101.3 kPa:

  • Are ignitable when in a mixture of 13% or less by volume with air.
  • Have flammable range with air of at least 12% regardless of the lower flammable limit.

Division 2.2 – Non-flammable, non-toxic gases:

  • Gases which are asphyxiant – gases which dilute or replace the oxygen normally in the atmosphere.
  • Gases which are oxidizing – gases which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does.
  • Do not come under the other divisions.

Division 2.3 – Toxic Gases

  • Gases which are known to be so toxic or corrosive to humans as to pose a hazard to health.
  • Are presumed to be toxic or corrosive to humans because they have an LC50 value equal to or less than 5000 ml/m³ (ppm)


Class 3 – Flammable Liquids

Class 3 is comprised of: liquids or mixtures of liquids, or liquids containing solids in solution or suspension (for example, paints, varnishes, lacquers, etc., but not including substances otherwise classified on account of their dangerous characteristics) which give off a flammable vapor.  This class also includes:

  • Liquids offered for transport at temperatures at or above their flash point; and
  • Substances that are transported or offered for transport at elevated temperatures in a liquid state and which give off a flammable vapour at a temperature at or below the maximum transport temperature.

Class 4 – Flammable Solids

Class 4 is comprised of substances liable to spontaneous combustion; substances which, in contact with water, emit flammable gases.

Division 4.1 – Solids which, under conditions encountered in transport, are readily combustible or may cause or contribute to fire through friction; self-reactive substances which are liable to undergo a strongly exothermic reaction; solid desensitized explosives which may explode if not diluted efficiently.

Division 4.2 – Substances liable to spontaneous combustion: substance which are liable to spontaneous heating under normal condition encountered in transport, or to heating up in contact with air, and being then liable to catch on fire.

Division 4.3 – Substances which in contact with water emit flammable gases: substances which, by interaction with water, are liable to become spontaneously flammable or to give off flammable gases in dangerous quantities.

Class 5 – Oxidizing Substances and Organic Peroxides

Division 5.1 – Oxidizing Substances: substances which, while in themselves not necessarily combustible, may, generally by yielding oxygen, cause or contribute to, the combustion of other material.

Division 5.2 – Organic Peroxides: contain the bivalent -O-O- structure and may be considered derivatives of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals.  Organic peroxides are thermally unstable substances, which may undergo exothermic self-accelerating decomposition.

Class 6 – Toxic and Infectious Substances

Division 6.1 – Toxic Substances: these are substances liable either to cause death or serious injury or to harm human health swallowed or inhaled or by skin contact.

Division 6.2 – Infectious Substances: these are substances known or reasonably expected to contain pathogens.  Pathogens are defined as microorganisms (including bacteria, viruses, rickettsiae, parasites, fungi) and other agents such as prions, which can cause disease in humans or animals.

Class 7 – Radioactive Material

Radioactive material means any material containing radionuclides where both the activity concentration and the total activity in the consignment exceed threshold values.



Class 8 – Corrosive Substances

Substances which, by chemical reaction, will cause severe damage when in contact with living tissue, or in the case of leakage, will materially damage, or even destroy, other goods or the means of transport.

Substances and preparations of Class 8 are divided among the three packing groups according to their degree of hazard in transport:

  • Packing Group I: Very dangerous substances and preparations.
  • Packing Group II: Substances and preparations presenting medium danger.
  • Packing Group III: Substances and preparations presenting minor danger.

Class 9 – Miscellaneous Dangerous Substances and Articles,
Including Environmentally Hazardous Substances

Class 9 substances and articles are those which, during transport present a danger not covered by other classes.

(Source: United Nations, Recommendations on the Transport of Dangerous Goods)

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