Worker in protective gear inspecting chemicals

Summary

HAZMAT—short for hazardous materials—refers to any substance or material capable of causing harm to people, property, or the environment when released, spilled, or improperly managed. These materials may be flammable, explosive, toxic, radioactive, corrosive, reactive, infectious, or otherwise dangerous because of their chemical, physical, or biological properties. In the U.S., the term is most closely tied to the Department of Transportation’s (DOT) classification system under 49 CFR, which governs the transportation of hazardous materials, but it’s also widely used in the Occupational Safety and Health Administration (OSHA), Environmental Protection Agency (EPA), and emergency response settings to identify substances that require special handling, packaging, training, and preparedness.

Key Takeaways

HAZMAT is the abbreviation for hazardous materials, which include substances capable of causing harm to people, property, or the environment.
Hazardous materials may present chemical, physical, biological, radiological, or environmental hazards depending on their characteristics.
OSHA, EPA, and DOT each regulate different aspects of hazardous material safety, including worker protection, waste management, and transportation requirements.
Workers should understand hazard communication, Safety Data Sheets (SDSs), labeling systems, and proper handling procedures before working with hazardous materials.
Selecting the appropriate personal protective equipment (PPE) depends on a site-specific hazard assessment and the hazards present.
Air monitoring, ventilation, decontamination, and emergency planning are essential components of safe hazardous material operations.
Hazardous materials are commonly encountered in manufacturing, construction, environmental remediation, healthcare, laboratories, transportation, utilities, and emergency response.
Employees involved in hazardous waste operations or emergency response activities may require HAZWOPER training under OSHA’s Hazardous Waste Operations and Emergency Response standard.
Employers are responsible for evaluating workplace hazards, providing appropriate training, supplying required PPE, and implementing safe work practices.
A strong safety culture, ongoing training, and regulatory compliance help minimize hazardous material incidents and protect workers, the public, and the environment.

In This Article

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DOT Definition of Hazardous Materials (HAZMAT)

Under DOT, a hazardous material or (HAZMAT)—as defined in 49 CFR §171.8—is any substance or material that the Secretary of Transportation determines is capable of posing an unreasonable risk to health, safety, or property when transported in commerce. This definition specifically applies to materials being shipped, offered for transport, or moved across public roads, railways, airways, or waterways.

DOT further clarifies that HAZMAT includes:

Any substance listed in the Hazardous Materials Table (49 CFR §172.101)
Materials that meet the criteria for any of the DOT hazard classes (Classes 1–9)
Hazardous substances, based on EPA reportable-quantity thresholds
Hazardous wastes, regulated under EPA’s Resource Conservation and Recovery Act (RCRA) but incorporated into DOT shipping rules
Marine pollutants
Elevated-temperature materials
Materials requiring special permits or handling

In short, if a material can endanger people, property, or the environment during transportation—and meets DOT’s classification criteria—it is regulated as a HAZMAT under 49 CFR. This definition forms the legal basis for packaging, marking, labeling, shipping papers, placarding, training, and emergency response requirements across the transportation industry.

The EPA Does Not Use “Hazardous Material” as an Official Regulatory Term

EPA does not define “hazardous material” or HAZMAT as a single regulatory category. Instead, the agency regulates materials that pose risk to human health or the environment under specific programs—primarily hazardous waste (RCRA), hazardous substances Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and extremely hazardous substances Emergency Planning and Community Right-to-Know Act (EPCRA). Any material that meets these criteria is considered hazardous when released, managed, stored, or disposed under EPA authority.

OSHA Definition of Hazardous Materials

OSHA defines hazardous materials or HAZMAT through the framework of its Hazard Communication Standard (29 CFR 1910.1200), which classifies any chemical that poses a physical or health hazard as a hazardous chemical. This includes flammable, explosive, reactive, corrosive, toxic, carcinogenic, and environmentally harmful substances, as well as simple asphyxiants and combustible dusts. While OSHA uses the term “hazardous materials” in several standards—such as Hazardous Waste Operations and Emergency Response (HAZWOPER)—the agency’s official regulatory definition is grounded in the classification of hazardous chemicals that can harm workers in the workplace.

Frequently Asked Questions

What does HAZMAT mean?

HAZMAT is short for hazardous materials. It refers to substances that can pose a risk to human health, property, or the environment because of their chemical, physical, or biological characteristics.

What are hazardous materials?

Hazardous materials include chemicals, gases, liquids, solids, biological agents, radioactive materials, and other substances capable of causing injury, illness, fire, explosion, environmental contamination, or property damage if not properly handled.

What types of hazards can hazardous materials present?

Hazardous materials may be flammable, combustible, explosive, corrosive, toxic, poisonous, oxidizing, reactive, radioactive, infectious, or environmentally hazardous. Many materials present more than one hazard.

Who works with hazardous materials?

Employees who commonly work with hazardous materials include environmental professionals, hazardous waste workers, emergency responders, laboratory personnel, industrial maintenance employees, utility workers, manufacturing personnel, transportation workers, healthcare professionals, and hazardous waste treatment, storage, and disposal facility (TSDF) employees.

What regulations govern hazardous materials?

Several federal agencies regulate hazardous materials depending on the activity being performed. OSHA establishes workplace safety requirements, EPA regulates hazardous waste management and environmental protection, and DOT governs the transportation of hazardous materials.

What is the difference between HAZMAT and HAZWOPER?

HAZMAT refers to hazardous materials themselves, while HAZWOPER is OSHA’s training and safety standard for employees involved in hazardous waste operations and emergency response to hazardous substance releases under 29 CFR 1910.120.

Do all employees working with hazardous materials need HAZWOPER training?

No. HAZWOPER training is required only for employees whose job duties fall within the scope of OSHA’s HAZWOPER standard. Other workers handling hazardous chemicals may instead require Hazard Communication training or other job-specific safety training.

What personal protective equipment (PPE) is used when working with hazardous materials?

The appropriate PPE depends on the hazards present and may include chemical-resistant clothing, gloves, safety glasses, face shields, protective footwear, and respiratory protection such as air-purifying respirators (APR) or self-contained breathing apparatus (SCBA).

Why is hazard communication important?

Hazard communication helps employees understand the hazards associated with the materials they work with through labels, Safety Data Sheets (SDSs), employee training, and standardized warning systems. Effective hazard communication reduces workplace injuries and improves regulatory compliance.

What should I do if a hazardous material is spilled?

Employees should follow their employer’s emergency response procedures, isolate the area if necessary, report the spill immediately, avoid unnecessary exposure, and respond only if they have received the appropriate training and are authorized to do so.

How can employers improve hazardous material safety?

Employers can improve HAZMAT safety by performing hazard assessments, providing appropriate training, maintaining written safety procedures, supplying proper PPE, conducting routine inspections, implementing emergency response plans, and encouraging employees to report unsafe conditions.

Why is proper HAZMAT training important?

Proper HAZMAT training helps employees recognize hazards, safely handle hazardous materials, respond appropriately during emergencies, protect themselves and others from exposure, and comply with applicable OSHA, EPA, and DOT regulations. Well-trained employees are better prepared to prevent incidents and contribute to a safer workplace.

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