HAZWOPER Glossary

This HAZWOPER glossary will help you to understand the most important terms associated with hazardous waste cleanup, emergency response, OSHA 40 training, air monitoring, PPE, decontamination and site safety. Each definition is written in plain language while maintaining the technical meaning used in OSHA regulations and hazardous waste operations.

50 Essential Terms and Definitions for HAZWOPER

HAZWOPER Training and Certification Terms

1. HAZWOPER

HAZWOPER stands for Hazardous Waste Operations and Emergency Response. It is the OSHA standard that protects employees who may be exposed to hazardous substances during certain cleanup operations, hazardous waste facility operations, and emergency responses.

HAZWOPER requirements are primarily found in 29 CFR 1910.120 for general industry and 29 CFR 1926.65 for construction.

2. HAZWOPER Training

HAZWOPER training prepares employees to perform hazardous waste and emergency-response duties without endangering themselves or other workers. The required training depends on the employee’s assigned duties, exposure potential, work environment, and emergency-response role.

Training may include hazard recognition, toxicology, PPE, respirators, air monitoring, decontamination, site control, emergency procedures, and safe work practices.

3. HAZWOPER Certification

HAZWOPER certification is the common term for documented completion of the required HAZWOPER instruction, practical training, and field experience. OSHA does not approve or endorse individual HAZWOPER courses or training providers, but the standard requires qualified instructors and supervisors to certify successful completion and issue a written certificate.

The employer remains responsible for verifying that an employee is adequately trained and competent for the work being performed.

4. OSHA 40 or 40-Hour HAZWOPER

OSHA 40 is a common name for 40-Hour HAZWOPER training. It applies to general site workers who remove hazardous substances or perform activities that expose or potentially expose them to hazardous substances and health hazards.

The requirement includes:

• At least 40 hours of off-site instruction
• At least three days of supervised field experience
• Site-specific training before site entry
• Eight hours of refresher training annually

5. 24-Hour HAZWOPER

The 24-Hour HAZWOPER course is intended for certain workers with limited duties and lower exposure potential. It may apply to employees who are on site only occasionally for a specific task and are unlikely to be exposed above applicable exposure limits.

It may also apply to employees working regularly in fully characterized areas where exposures are below applicable limits, respirators are unnecessary, and no health hazard or emergency is expected. The requirement includes at least one day of supervised field experience.

6. 8-Hour HAZWOPER Refresher

The 8-Hour HAZWOPER Refresher is the annual training required for employees covered by the 40-hour or 24-hour cleanup-worker requirements. It reviews relevant HAZWOPER subjects, changes in site operations, lessons learned from incidents, and other topics connected to the employee’s duties.

Managers and supervisors covered by the cleanup provisions also receive the annual refresher.

7. HAZWOPER Training Levels

HAZWOPER training levels are determined by the employee’s duties and exposure potential—not simply by which course the employee prefers to take. The standard contains separate requirements for uncontrolled-site cleanup workers, RCRA treatment, storage and disposal facilities, and hazardous-substance emergency responders.

Common training categories include:

• 40-Hour General Site Worker
• 24-Hour Limited-Task Worker
• 8-Hour Annual Refresher
• HAZWOPER Supervisor
• First Responder Awareness
• First Responder Operations
• Hazardous Materials Technician
• Hazardous Materials Specialist
• On-Scene Incident Commander

8. Online HAZWOPER Training

Online HAZWOPER training can deliver the knowledge-based portion of the required instruction, but computer-based instruction alone does not satisfy every HAZWOPER training obligation. Workers must also have access to a qualified trainer, opportunities to ask questions, practical instruction, and assessment of hands-on skills.

The employer must separately ensure that site-specific instruction and supervised field experience are completed.

9. Hands-On HAZWOPER Training

Hands-on HAZWOPER training gives employees practical experience using the PPE, respirators, instruments, equipment, and procedures required for their duties. OSHA has stated that initial instruction must include an actual hands-on component rather than relying entirely on lectures or computer-based lessons.

Hands-on instruction should allow workers to practice tasks such as:

• Donning and doffing PPE
• Using respirators
• Operating air-monitoring instruments
• Performing decontamination
• Using spill-control equipment
• Communicating during emergencies

10. Site-Specific HAZWOPER Training

Site-specific training teaches workers about the actual hazards, controls, procedures, and emergency arrangements at the site where they will work. Even previously certified employees must receive appropriate site-specific instruction before entering a new hazardous waste site.

Site-specific training commonly covers the HASP, contaminants, PPE, monitoring, work zones, communications, decontamination, emergency signals, and evacuation procedures.

11. Supervised Field Experience

Supervised field experience allows a worker to apply HAZWOPER knowledge under the direct supervision of a trained and experienced supervisor. The 40-hour cleanup-worker requirement includes at least three days of field experience, while qualifying 24-hour workers receive at least one day.

Field experience is part of initial qualification and is not replaced by completion of the online or classroom portion.

12. HAZWOPER Supervisor Training

HAZWOPER supervisors must receive the training and field experience required for the employees they supervise, plus at least eight additional hours of specialized supervisory training at the time of assignment.

Specialized subjects include:

• The employer’s safety and health program
• Employee training
• PPE selection and use
• Spill containment
• Health-hazard monitoring
• Implementation of the site-specific HASP

13. HAZWOPER Expiration or Renewal

HAZWOPER cleanup workers are required to receive eight hours of refresher training annually, generally within 12 months of their previous training. A missed anniversary does not create one automatic retraining rule for every worker; the employer must evaluate the worker’s familiarity, retained competency, previous experience, and current assignment.

A worker who misses the refresher should take the next available course. A lengthy absence may require more than eight hours or repetition of portions of the initial training.

14. 29 CFR 1910.120

29 CFR 1910.120 is OSHA’s general-industry Hazardous Waste Operations and Emergency Response standard. It contains requirements for hazardous waste site cleanup, RCRA treatment, storage and disposal operations, and emergency response to hazardous-substance releases.

The comparable construction-industry standard is 29 CFR 1926.65.

15. HAZWOPER Scope and Application

HAZWOPER applies to five major categories of work involving actual or potential exposure to hazardous substances.

They are:

1. Government-required cleanup at uncontrolled hazardous waste sites
2. RCRA corrective-action cleanup
3. Voluntary cleanup at government-recognized uncontrolled sites
4. Certain operations at RCRA treatment, storage and disposal facilities
5. Emergency response to releases or substantial threats of releases of hazardous substances

HAZWOPER does not apply to every workplace that uses a hazardous chemical. The type of operation, release, exposure potential, and employee responsibilities must be evaluated.

Hazardous Waste and Regulatory Terms

16. Hazardous Substance

A hazardous substance is a broad regulatory category covering materials that may create serious health, safety, environmental, fire, explosion, corrosivity, toxicity, or other hazards. Under HAZWOPER, the term includes substances designated under several federal environmental and workplace laws and certain biological or disease-causing agents.

A hazardous substance is not necessarily a waste. A raw material, process chemical, product, or released material may qualify.

17. Hazardous Waste

Hazardous waste is discarded material with properties that make it dangerous or capable of harming human health or the environment. Under RCRA, a waste may be hazardous because it is specifically listed or because it exhibits a hazardous-waste characteristic.

The primary hazardous-waste characteristics are:

• Ignitability
• Corrosivity
• Reactivity
• Toxicity

18. Uncontrolled Hazardous Waste Site

An uncontrolled hazardous waste site is a government-identified area where accumulated hazardous substances threaten human health, safety, the environment, or a combination of these.

Examples may include abandoned disposal areas, former industrial sites, illegal dumps, contaminated landfills, and government-recognized remediation sites.

19. RCRA

RCRA stands for the Resource Conservation and Recovery Act. It establishes the federal framework for managing hazardous waste from generation through treatment, storage, and final disposal.

HAZWOPER may apply to:

• Corrective-action cleanup at RCRA-covered sites
• Certain operations at permitted treatment, storage and disposal facilities
• Emergency response involving hazardous substances at regulated facilities

20. CERCLA or Superfund

CERCLA stands for the Comprehensive Environmental Response, Compensation, and Liability Act and is commonly called Superfund. It authorizes investigation and cleanup of contaminated sites and provides mechanisms for identifying responsible parties.

Government-required or government-recognized cleanup at a qualifying uncontrolled site may fall under HAZWOPER.

21. Treatment, Storage and Disposal Facility

A treatment, storage and disposal facility, or TSDF, is a facility that treats, stores, or disposes of hazardous waste under the RCRA regulatory system. Certain employees at permitted or interim-status TSDF operations are covered by paragraph 1910.120(p).

Covered TSDF employees generally receive:

• 24 hours of initial training
• Eight hours of refresher training annually
• Facility-specific emergency-response training where applicable

Site Planning and Control Terms

22. Health and Safety Plan

A Health and Safety Plan, commonly called a HASP, is the site-specific document that describes how workers will be protected during hazardous waste operations. The HASP must be kept on site and address the hazards and protective procedures for each phase of the operation.

A complete HASP commonly addresses:

• Hazard analysis
• Training assignments
• PPE
• Medical surveillance
• Air monitoring
• Site control
• Decontamination
• Emergency response
• Confined-space procedures
• Spill containment

23. Site Characterization

Site characterization is the process of collecting and evaluating information to identify site hazards and determine the controls needed to protect employees.

Information may come from:

• Historical records
• Site inspections
• Interviews
• Safety data sheets
• Air monitoring
• Environmental sampling
• Maps and drawings
• Container inventories
• Previous investigation reports

Site characterization begins before entry and continues as operations reveal new information.

24. Initial Entry

Initial entry is the first controlled entry into a hazardous waste site or work area for the purpose of evaluating conditions and beginning planned operations. Representative air monitoring must identify potential IDLH conditions, excessive exposures, flammable atmospheres, oxygen deficiency, radiological hazards, and other dangerous conditions.

Where hazards are not sufficiently identified, OSHA requires conservative protection and appropriate direct-reading instruments.

25. Site Control Program

A site control program organizes people, equipment, communications, and work areas to reduce exposure and prevent contaminants from spreading.

The program must include, at minimum:

• A site map
• Clearly identified work zones
• The buddy system
• Site communications
• Emergency-alert procedures
• Safe work practices
• Identification of nearby medical assistance

26. Exclusion Zone

The Exclusion Zone is the contaminated or potentially contaminated work area where access is restricted to authorized, trained, and properly protected personnel. It is frequently called the Hot Zone.

The boundary should reflect contamination, monitoring results, work activities, wind direction, physical hazards, and the potential for conditions to change.

27. Contamination Reduction Zone

The Contamination Reduction Zone, or CRZ, is the controlled transition area between the Exclusion Zone and the clean Support Zone.

The CRZ commonly contains the decontamination corridor, personnel-control points, equipment drop areas, and procedures designed to prevent contaminants from reaching clean areas.

28. Support Zone

The Support Zone is the clean area outside the contaminated and decontamination zones. It is used for command, administration, medical support, equipment staging, communications, and other functions that should remain free from site contamination.

It is also commonly called the Cold Zone.

29. Buddy System

The buddy system organizes employees so that every worker is observed by at least one other worker who can provide or summon rapid assistance during an emergency.

The buddy system does not replace rescue planning, communications, standby personnel, or the additional requirements that apply to IDLH entry.

30. Decontamination

Decontamination is the controlled removal, neutralization, cleaning, or isolation of hazardous substances from workers, PPE, instruments, tools, and equipment. Decontamination procedures must be developed, communicated, and implemented before employees or equipment enter areas where exposure may occur.

The decontamination method must account for the contaminant, PPE ensemble, work activity, environmental conditions, waste handling, and potential for secondary exposure.

31. Medical Surveillance

Medical surveillance is an employer-managed program used to evaluate the health of certain employees who may be significantly exposed to hazardous substances or who perform designated HAZWOPER duties.

Coverage may include:

• Employees exposed above applicable limits for 30 or more days per year
• Employees who wear respirators for 30 or more days per year
• Members of organized HAZMAT teams
• Employees who develop signs or symptoms of overexposure
• Employees injured or exposed during an emergency

Medical surveillance is different from emergency first aid or treatment after an incident.

Air Monitoring and Exposure Terms

32. Air Monitoring

Air monitoring is the use of direct-reading instruments, sampling equipment, and analytical methods to identify airborne hazards and evaluate worker exposure. Monitoring results support decisions about PPE, respiratory protection, engineering controls, work practices, site boundaries, and emergency actions.

Air monitoring may be:

• Initial
• Periodic
• Continuous
• Personal
• Area-based
• Perimeter-based
• Task-specific

33. Personal Air Sampling

Personal air sampling measures the exposure of an individual employee during a task, part of a shift, or a full work shift. Sampling equipment is worn by the employee so the result represents that worker more closely than a stationary area monitor.

After cleanup work begins, OSHA requires monitoring of employees expected to have the highest exposures and expansion of sampling when results indicate that other workers may also exceed applicable limits.

34. Permissible Exposure Limit

A Permissible Exposure Limit, or PEL, is an OSHA occupational exposure limit that employers are legally required to follow. A PEL may be expressed as a time-weighted average, short-term limit, ceiling limit, or another substance-specific exposure restriction.

A PEL is not the level at which every employee will experience symptoms, and compliance with a PEL does not eliminate the need to evaluate skin exposure, acute hazards, or more protective published limits.

35. Recommended Exposure Limit

A Recommended Exposure Limit, or REL, is an occupational exposure recommendation established by NIOSH.RELs may be expressed as time-weighted averages, short-term limits, or ceiling values.

When OSHA has no applicable PEL, employers may consider RELs and other credible published exposure limits when selecting protective controls.

36. Immediately Dangerous to Life or Health

IDLH means an atmosphere that poses an immediate threat to life, may cause irreversible or delayed adverse health effects, or could prevent a worker from escaping.

Unknown concentrations and most oxygen-deficient atmospheres must be treated conservatively. Entry into IDLH conditions requires highly reliable positive-pressure respiratory protection and specific standby and rescue arrangements.

37. Short-Term Exposure Limit

A Short-Term Exposure Limit, or STEL, is the maximum average exposure permitted or recommended over a short period, commonly 15 minutes.

A full-shift exposure may be below the TWA limit while a short task still exceeds the STEL.

38. Time-Weighted Average

A Time-Weighted Average, or TWA, is the average airborne concentration to which a worker is exposed over a defined period. OSHA limits commonly use an eight-hour workday, while many NIOSH RELs use up to a 10-hour workday during a 40-hour workweek.

A TWA can conceal brief concentration spikes, so short-term and ceiling limits must also be considered.

39. Lower Explosive Limit

The Lower Explosive Limit, or LEL, is the minimum concentration of a gas or vapor in air that can burn when an ignition source is present. Below the LEL, the mixture is generally too lean to burn.

Combustible-gas monitors commonly display a percentage of the LEL. A display of 10% LEL means the instrument is indicating one-tenth of the concentration associated with the lower explosive limit for the gas and calibration conditions involved.

40. Photoionization Detector

A Photoionization Detector, or PID, is a direct-reading instrument used to screen for many volatile organic compounds and other ionizable vapors. A PID can help locate vapor sources and track changing concentrations, but it generally cannot identify a chemical solely from the displayed reading.

PID response depends on:

• Lamp energy
• Chemical ionization potential
• Calibration gas
• Response factor
• Humidity
• Interferences
• Instrument condition

A zero PID reading does not prove that every toxic contaminant is absent.

PPE and Respiratory Protection Terms

41. Personal Protective Equipment

Personal protective equipment, or PPE, includes clothing and equipment worn to reduce exposure to chemical, physical, biological, radiological, and other workplace hazards. At a HAZWOPER site, PPE must be selected for the specific contaminants, concentrations, exposure routes, tasks, environmental conditions, and emergency potential.

The commonly referenced Levels A, B, C, and D are selection guidelines rather than substitutes for a site-specific hazard assessment.

42. Level A PPE

Level A provides the greatest combined level of skin, respiratory, and eye protection. A typical Level A ensemble includes a totally encapsulating chemical-protective suit with a positive-pressure SCBA enclosed inside the suit.

Level A may be appropriate when:

• A severe skin hazard is known or suspected
• High vapor concentrations may be present
• Splash, immersion, or vapor exposure is possible
• Conditions are poorly characterized
• The absence of a Level A hazard has not been established

43. Level B PPE

Level B provides the highest level of respiratory protection but less skin protection than Level A. It normally includes a positive-pressure SCBA or supplied-air respirator with escape SCBA and chemical-resistant splash-protective clothing.

In a typical Level B ensemble, the SCBA cylinder is worn outside the chemical-protective suit.

44. Level C PPE

Level C uses an air-purifying respirator with chemical-protective clothing appropriate for the identified hazards. It may be used only when contaminants are known, concentrations have been measured, sufficient oxygen is present, the correct cartridges or filters are available, and all APR-use criteria are satisfied.

Level C is not appropriate for an unknown atmosphere or an IDLH condition.

45. Level D PPE

Level D is a basic work uniform that provides minimal protection and no respiratory protection. It is used only where the atmosphere contains no known hazard and the work does not create a significant potential for hazardous inhalation, splash, immersion, or skin contact.

Level D may include coveralls, safety footwear, gloves, safety glasses, and a hard hat as required by the work.

46. Self-Contained Breathing Apparatus

A Self-Contained Breathing Apparatus, or SCBA, is an atmosphere-supplying respirator in which the breathing-air source is carried by the user.

A full-facepiece, positive-pressure SCBA is used for many unknown or IDLH atmospheres because it does not depend on the surrounding air for oxygen or contaminant removal.

47. Air-Purifying Respirator

An Air-Purifying Respirator, or APR, removes specific contaminants from ambient air using filters, cartridges, or canisters.

An APR:

• Does not provide oxygen
• Must be matched to the contaminant
• Requires sufficient oxygen
• Requires known and measured conditions
• Must not be used in an IDLH atmosphere
• Requires a cartridge-change schedule or approved end-of-service-life indicator where applicable

48. Supplied-Air Respirator

A Supplied-Air Respirator, or SAR, delivers breathing air from a remote source through an airline rather than carrying the primary air supply on the worker’s back.

For IDLH entry, an SAR must be configured as an approved positive-pressure system with an appropriate auxiliary escape SCBA. Airline length, air quality, escape capability, hose protection, and compressor placement must all be controlled.

Emergency-Response Terms

49. Emergency Response Versus Incidental Release

An emergency response involves an uncontrolled or potentially uncontrolled hazardous-substance release requiring action by employees outside the immediate release area or by designated emergency responders. An incidental release is limited enough that trained employees in the immediate area can safely control it using available equipment and established procedures.

The distinction depends on factors such as:

• Quantity released
• Toxicity
• Flammability
• Volatility
• Confined-space conditions
• Ventilation
• Employee knowledge
• Available PPE
• Available control equipment
• Potential for the release to escalate

A spill is not incidental merely because the quantity appears small.

50. HAZWOPER Emergency-Response Levels

HAZWOPER emergency-response levels define what responders are trained and authorized to do during a hazardous-substance release. Training must be based on the duties and functions each responder is expected to perform.

First Responder Awareness Level

Recognizes a release, protects themselves, initiates the emergency-response sequence, and notifies the appropriate authorities. Awareness-level personnel take no further response action.

First Responder Operations Level

Responds defensively to protect people, property, and the environment. Operations-level personnel may contain or confine a release from a safe distance but do not approach the source to stop it.

Hazardous Materials Technician

Approaches the point of release to plug, patch, close, or otherwise stop the release. The technician performs offensive control actions using specialized PPE, instruments, and procedures.

Hazardous Materials Specialist

Provides advanced substance-specific knowledge and technical support to hazardous materials technicians. The specialist may also serve as liaison with federal, state, local, and other government agencies.

On-Scene Incident Commander

Assumes control of the incident scene and directs the response through the Incident Command System. The Incident Commander evaluates hazards, establishes objectives, coordinates resources, and ensures responders operate within the emergency-response plan.

51. TLV – Threshold Limit Value

The chemical exposure guidelines recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). While PELs are the legally enforceable limits, TLVs are often stricter, representing the maximum airborne concentration to which nearly all workers can be exposed daily without adverse health effects. 

52. ERG – Emergency Response Guidebook

 A guide developed jointly by the DOT, Transport Canada, and the Secretariat of Communications and Transportation of Mexico. It is the primary resource used by first responders and HAZWOPER-certified personnel to quickly identify specific or generic hazards of materials involved in a transportation incident and protect themselves during the initial response phase.