Hazard Classes: How Many Are There for Fully Regulated Items?

Hazardous materials and dangerous goods are transported daily around the United States. To keep everyone safe, the U.S. Department of Transportation regulates how materials are packaged, labeled, and transported based on the type of risk they present and the conditions under which the item is dangerous.

These materials are separated into different classes depending on how hazardous they are. These are the DOT hazard classes, and anyone involved in commercial road, rail, air, marine, or pipeline transportation should be aware of what they are to prevent accidents.

So how many HazMat classes are there, and which ones are the most dangerous? Keep reading to find out.

How Does the DOT Regulate Hazardous Goods?

In order to mitigate the risks of hazmat exposure during transport, the DOT issues and enforces the Hazardous Materials Regulations (HMR) under Title 49 of the Code of Federal Regulations (CFR).

DOT Hazardous Materials Regulations fall into four general types of requirements:

• Operational rules
• HazMat identification and classification
• Hazard communication
• Packaging requirements

By creating these classifications and setting labeling requirements, the DOT has made it easier for everyone along the transportation route to know what precautions need to be taken.

How Many Hazard Classifications Are Used By the DOT?

The DOT classifies hazardous materials and dangerous goods into nine categories.

The 9 DOT hazard classes are:

• Class 1: Explosives
• Class 2: Gases
• Class 3: Flammable Liquid and Combustible Liquid
• Class 4: Flammable Solid, Spontaneously Combustible, and Dangerous When Wet
• Class 5: Oxidizer and Organic Peroxide
• Class 6: Poison (Toxic) and Poison Inhalation Hazard
• Class 7: Radioactive
• Class 8: Corrosive
• Class 9: Miscellaneous

DOT categories help the agencies regulate the types of containers that are safe for each class (and subclass) of materials, as well as which materials should never be loaded, transported, or stored together.

How Many Hazard Classes for Fully Regulated Items vs. Partially Regulated Items?

You'll see the phrase "fully regulated" when it comes to hazard classes. Does that mean there are partially regulated hazard classes?

Not exactly.

There are nine hazard classes laid out in the Hazard Materials Regulations. Most of the items that fall into one of these hazard classes are "fully regulated," meaning that all requirements apply to those shipments.

However, some exemptions apply to various hazard classes, where only some of the HMR requirements apply. In these cases, the goods are "partially regulated," although no one uses that terminology.

Essentially, each class is "mostly fully regulated" and "occasionally partially regulated."

What Is in Each of the DOT Hazard Classes?

DOT hazard classes group dangerous goods together based on their physical and chemical properties.

Each DOT class (and many of the subclasses) comes with requirements for special placards, types of packaging, and labeling.

Class 1 Hazardous Materials: Explosives

DOT Class 1 is explosive, meaning they can produce hazardous amounts of heat, light, sound, smoke, or gas at damaging speeds and pressures.

Special permits are required to transport certain DOT Class 1 materials. For the most hazardous divisions of 1.1 and 1.2, transportation must follow pre-planned routes that avoid bridges, tunnels, fires, or crowded places.

Class 1 examples include dynamite, ammonium nitrate–fuel oil (ANFO), fireworks, ammunition, blasting agents, blasting caps, and detonating cords.

Class 2 Hazardous Materials: Gases

All gases that are compressed and stored for transportation are in the HazMat Class 2 category. Some of these gases are inherently dangerous because they're toxic or flammable.

However, even non-flammable, non-toxic gases are hazardous, either because they're under pressurized storage or because they're a potential asphyxiant.

Common examples of Class 2 hazardous materials include propane, helium, oxygen, and aerosols.

Class 3 Hazardous Materials: Flammable/Combustible Liquids

Flammable and combustible liquids are HazMat Class 3. They have to be stored in containers designed to prevent leaks or spills.

DOT Class 3 examples include acetone, paint, gasoline, adhesives, and certain pesticides.

Class 4 Hazardous Materials: Flammable Solids

Class 4 materials are solids that ignite easily and burn rapidly. This includes self-reactive substances, desensitized explosives, materials that can spontaneously combust, and those that have certain reactions to water.

As a result, they need to be stored in containers designed to prevent ignition and labeled with specific warnings, like "Dangerous When Wet" for Division 3 substances that emit flammable gases when they come into contact with water.

Examples of Class 4 hazardous materials include magnesium and matches.

Class 5 Hazardous Materials: Oxidizers

Oxidizing materials and organic peroxides are categorized HazMat Class 5 because they're highly reactive and can cause other materials to burn or explode, even if they're not combustible themselves. To prevent accidental combustion or explosion, DOT Class 5 materials have special handling instructions.

Examples of hazardous oxidizers include hydrogen peroxide and potassium permanganate.

Class 6 Hazardous Materials: Toxic

HazMat Class 6 items are substances with oral, dermal, or inhalation toxicity, as well as infectious biohazards.

Pesticides, lead, live pathogens, and used sharps such as hypodermic needs or disposable razor blades all fall under the Class 6 category.

Class 7 Hazardous Materials: Radioactive

The DOT categorizes all substances that emit ionizing radiation as Class 7 because ionizing radiation can cause long-term health problems. Special permits and training are required for Class 7 materials transportation.

Examples of DOT Class 7 include uranium and plutonium.

Class 8 Hazardous Materials: Corrosive

HazMat Class 8 is for materials that can degrade or disintegrate other materials upon contact through a chemical reaction. Corrosiveness to human skin is often the reference point, but materials with severe corrosion rates on steel or aluminum also qualify.

Examples include any solutions with a pH below 2 (extremely acidic) or over 12.5 (extremely basic). Since car batteries contain sulfuric acid, they're categorized as Class 8.

Class 9 Hazardous Materials

HazMat Class 9 materials are substances that present an imminent threat not covered by the other eight DOT classes.

In 2017, lithium batteries became a new subclass, HazMat 9A, which requires special labeling.

Otherwise, this category may include:

• Environmentally hazardous substances
• Substances that are transported at elevated temperatures
• Genetically modified organisms and micro-organisms
• Magnetized materials
• Aviation-regulated substances
• Miscellaneous articles and substances

Who Needs DOT HazMat Training?

The DOT requires "HazMat employers" to train "HazMat employees" every three years in the Hazardous Materials Regulations that are relevant to their jobs.

That's a rabbit hole of things that need defining, so here we go.

DOT defines a "HazMat employer" as any person or entity who uses employee(s) in connection with

• Transporting hazardous materials in commerce
• Causing hazardous materials to be shipped in commerce
• Repairing or modifying the containers/drums/packages used in the transportation of hazardous materials

DOT defines a "HazMat employee" as anyone whose job duties affect HazMat transportation safety. That includes responsibilities like:

• Preparing hazardous materials for transportation
• Handling, loading, or unloading hazardous materials
• Operating a vehicle that is transporting hazardous materials
• Exercising responsibility for the safety of hazardous material transportation
• Manufacturing, testing, reconditioning, repairing, modifying, marking, or otherwise representing containers/drums/packages as qualified for use in the transportation of hazardous materials

Get Your DOT HazMat Training Online

We offer a full suite of DOT HazMat courses to help you comply with the HMR training mandate. These courses are online and self-paced, so you can study whenever and wherever it's convenient for you.

Get started today!

https://www.osha.com/courses/transportation.html