HAZMAT products are broken into nine classes, ranging from the most extreme materials like explosives, gases, toxic materials, and radioactive materials to more seemingly minor products like hair spray, liquor, and nail polish that still pose a shipping and handling risk. Each of these classes has a specific sub class that also provides more details on the classification.
 

1.Class 1: Explosives

As the name implies, these are products likely to explode under certain conditions.

• Division 1.1: Explosives with a mass explosion hazard
• Division 1.2: Explosives with a projection hazard
• Division 1.3: Explosives with predominantly a fire hazard
• Division 1.4: Explosives with no significant blast hazard
• Division 1.5: Very insensitive explosives
• Division 1.6: Extremely insensitive explosive articles

Examples of Class 1 HAZMAT products include ammunition, gun powder, fireworks, airbag inflators, and seat belt pretensioners.

2.Class 2: Gases

These are products that contain gases that are dangerous when inhaled or when they make contact with a surface.

• Division 2.1: Flammable gases
• Division 2.2: Non-flammable gases
• Division 2.3: Poison gases
• Division 2.4: Corrosive gases

Examples of Class 2 HAZMAT products include aerosols (spray paint, household cleaners, bathroom sprays, and spray cosmetics such as hair care products, deodorants, and perfumes), propane tanks, lighters, pepper spray, scuba tanks, self-inflating rafts, and fire extinguishers.

3.Class 3: Flammable liquids

These are liquids that will ignite when making contact with fire.

• Division 3.1: Flashpoint below -18°C (0°F)
• Division 3.2: Flashpoint below -18°C and above, but less than 23°C (73°F)
• Division 3.3: Flashpoint 23°C and up to 61°C (141°F)

Examples of Class 3 HAZMAT products include gasoline, nail polish, lighter refills, oil-based paints, paint thinner, and varnish.

4.Class 4: Flammable solids

Products that will ignite when making contact with fire fall into this category.

• Division 4.1: Flammable solids
• Division 4.2: Spontaneously combustible materials
• Division 4.3: Materials that are dangerous when wet

Examples of Class 4 HAZMAT products include matches, sulfur, coal, fish oil, potassium, sodium, and sodium batteries.

5.Class 5: Oxidizers/organic peroxides

These are chemicals that readily yield oxygen in reactions, thereby causing or enhancing combustion.

• Division 5.1: Oxidizers
• Division 5.2: Organic peroxides

Examples of Class 5 HAZMAT products include ammonium nitrate fertilizers, bleach, hydrogen peroxide, chlorine, and sodium nitrate.

6.Class 6: Toxic and infectious substances

In this class are substances that can cause death, serious injury, or harm to humans if inhaled or swallowed. Infectious substances are known to carry pathogens (bacteria, viruses, fungi, etc.).

• Division 6.1: Poisonous materials
• Division 6.2: Etiologic (infectious) materials

Examples of Class 6 HAZMAT products include biomedical waste (e.g., blood samples and used needles), arsenic, pesticides, and nicotine.

7.Class 7: Radioactive material

This is any material or combination of materials that spontaneously gives off ionizing radiation. It has a specific activity greater than 0.002 microcuries per gram.
Examples of Class 7 HAZMAT products include medical isotopes, radioactive medicines, isotopes used in research (Carbon-14, etc.), X-ray machines, and depleted uranium.

8.Class 8: Corrosives

A corrosive is a material, liquid, or solid that causes visible destruction or irreversible alteration to human skin or a liquid that has a severe corrosion rate on steel or aluminum.
Examples of Class 8 HAZMAT products include sulfuric acid, hydrochloric acid, sodium hydroxide, wet and NiCad batteries, drain cleaner, paint and paint stripper, and mercury thermometers and barometers.

9.Class 9: Miscellaneous hazardous materials

Products in this class include materials that present a hazard during transport but are not included in another hazardous freight classification.
Examples of Class 9 HAZMAT products include dry ice, lithium-ion batteries, vehicles, and first-aid kits.
Read more from the Federal Aviation Administration (FAA): Commonly Shipped Undeclared Hazardous Materials.

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