DOT Hazard Classes

The DOT separates hazardous materials into nine different categories or “hazard classes.” They are defined by specific hazardous properties and have distinct regulatory requirements for packaging, markings, and labels. Keep reading for a general summary of those properties.

Hazard Class 1 – Explosives

Explosives 1.3.1
Explosives 1.4
Blasting Agents 1.5
Explosives 1.2.1
Explosives 1.1.1

The explosives hazard class is divided into six categories based on the kind of explosive hazard:

  • Mass explosion
  • Projection
  • Fire
  • Level of sensitivity

Explosives that most people are familiar with include dynamite, gun powder, and fireworks.

Hazard Class 2 – Gases

Flammable Gas 2
Non-Flammable Gas 2

Gases have three divisions:

  • Flammable gases (2.1) burn readily in air and are in a gaseous state at 68°F (e.g., propane and spray paints).
  • Non-flammable gases (2.2) may include liquified gases or cryogenic liquids (e.g., helium and asthma inhalers).
  • Poisonous gases (2.3) are toxic or presumed toxic to humans (e.g., carbon monoxide).

Hazard Class 3 – Flammable Liquids

Flammable liquids have a “flash point” of 140°F or less. A flash point is the temperature when an ignition source near the liquid can ignite the vapors. Examples of flammable liquids include the following:

  • Gasoline
  • Acetone
  • Ethanol
  • Xylene
  • Many paints and common solvents
Flammable Liquid

Hazard Class 4 – Flammable Solids

Spontaneous Combustible
Flammable Solids
Dangerous When Wet


These are the three divisions of flammable solids along with a common example for each:

  • Flammable solid (4.1) (e.g., match sticks),
  • Spontaneously combustible material (4.2) (e.g., oily rags)
  • Dangerous when wet (4.3) (e.g., magnesium fire starter)

Hazard Class 5 – Oxidizing Substance & Organic Peroxide

Organic Peroxide


Oxidizers (5.1) may contribute to the combustion of other materials. Concentrated hydrogen peroxide and silver nitrate are both examples of oxidizers.

Organic peroxides (5.2) contain both an oxidizer and an organic fuel. They are thermally unstable and can release dangerous amounts of heat and energy. They are sometimes used to initiate polymerization of epoxy resins.

Hazard Class 6 – Toxic & Infectious Substances

Toxic or poisonous material (6.1) can be solids or liquids known or presumed to be toxic to humans. Classification is based on oral, dermal, and inhalation exposure. In high doses, some medications are toxic, such as coumadin. Division 6.2 Infectious Substances are materials that are known or reasonably expected to contain a pathogen.


Hazard Class 7 – Radioactive

Uranium and plutonium are not the only radioactive materials. Exit signs, smoke detectors, and x-ray equipment are a few common sources of radioactive material in our day-to-day lives.


Hazard Class 8 – Corrosive Materials

Acids (low pH) and bases (high pH) are corrosive materials that can eat away at skin and steel. Sources for corrosive material include battery acid and degreasers.

Corrosive Materials

Hazard Class 9 – Miscellaneous Hazardous Material

Class 9 materials pose a hazard during transportation, so they are regulated when shipped, but they do not meet the definition of the previously listed hazard classes. Formalin sample containers and liquids fall under the class 9 category.

Miscellaneous Hazardous Material

Remember that small and large quantity generators of hazardous wastes must notify the EPA of their generation activities and receive an EPA identification number. Some states have stricter regulations. If you need help identifying your hazardous waste, contact Sharps Compliance. We offer comprehensive solutions for the management of regulated medical waste, hazardous waste, and unused medications.

Chandra Lippitt has a Bachelor of Science degree in Chemistry from Colorado School of Mines. She is certified in RCRA and DOT as well as 40 Hour HAZWOPER certified. Chandra has been in the hazardous waste industry since 2008 and has managed industrial, healthcare, retail, and governmental clients, both large and small.

published in Hazardous Waste