HAZWOPER guide · 8 min read · Updated 2026-11-03

HAZWOPER Glossary: 71 Terms and Acronyms Explained

Plain-English definitions of the terms and acronyms used in HAZWOPER training, OSHA 29 CFR 1910.120, EPA RCRA and hazardous materials work. Use the site search to jump to a term, or follow the links to the full guides.

Terms A to Z

Access control point
A controlled entry and exit point between work zones, where workers check in and out and pass through decontamination. Learn more
Acute exposure
A single or short-term exposure to a substance, usually at a high concentration, with effects that appear quickly. Learn more
APR (air-purifying respirator)
A respirator that removes contaminants from ambient air with filters or cartridges. Used in Level C; not for oxygen-deficient or IDLH atmospheres. Learn more
Buddy system
Organizing workers into groups so each one is observed by at least one other worker who can help or call for help in an emergency. Learn more
Bump test
A quick check that exposes a gas detector to a known gas to confirm its sensors and alarms respond. Usually done before each day's use. Learn more
CAS number
A unique number assigned by the Chemical Abstracts Service to identify a chemical substance.
Ceiling limit (C)
An exposure concentration that must never be exceeded, even briefly. Learn more
CERCLA
The Comprehensive Environmental Response, Compensation, and Liability Act of 1980, also called Superfund. It funds and directs cleanup of uncontrolled hazardous waste sites. Learn more
CGI (combustible gas indicator)
An instrument that measures flammable gases and vapors as a percentage of the lower explosive limit (LEL). Learn more
Chronic exposure
Repeated or continuous exposure over a long period, which can cause long-term health effects such as cancer or organ damage. Learn more
Colorimetric tube
A glass tube filled with a reagent that changes color when air containing a specific chemical is drawn through it, giving an estimated concentration. Learn more
Confined space
A space large enough to enter, with limited means of entry or exit, and not designed for continuous occupancy, such as tanks, vaults, pits and trenches.
Contamination reduction zone (CRZ)
The warm zone between the exclusion zone and the support zone, where decontamination takes place. Learn more
Contingency plan
A written plan required for large quantity generators and TSDFs describing actions to take in a fire, explosion or release of hazardous waste. Learn more
Decontamination (decon)
Removing or neutralizing contaminants from people and equipment so hazards do not leave the work area. Learn more
Direct-reading instrument
A monitoring device that gives real-time readings of air contaminants on site, such as a 4-gas meter or PID. Learn more
Emergency response
A response effort by employees from outside the immediate release area, or by other designated responders, to an occurrence that results, or is likely to result, in an uncontrolled release of a hazardous substance. Learn more
ERG (Emergency Response Guidebook)
The U.S. DOT guide first responders use to identify hazardous materials by UN/NA number or name and find initial protective actions. Learn more
Exclusion zone (EZ)
The hot zone where contamination is or could be present. Entry requires the specified PPE. Learn more
FID (flame ionization detector)
An instrument that detects organic vapors, including methane, by burning the sample in a hydrogen flame. Learn more
First responder awareness level
Responders who are likely to witness or discover a release and are trained only to start the response by notifying authorities. Learn more
First responder operations level
Responders who act defensively to protect people, property and the environment from a release, without trying to stop it. At least 8 hours of training. Learn more
Hazardous substance
Under HAZWOPER, any substance designated under CERCLA, biological or disease-causing agents, DOT hazardous materials, and hazardous wastes. Learn more
Hazardous waste
Waste listed by EPA or showing a hazardous characteristic: ignitability, corrosivity, reactivity or toxicity. Learn more
HASP
Health and safety plan: the site-specific safety and health plan required by 1910.120(b)(4). Learn more
HAZMAT team
An organized group of employees designated by the employer to handle and control actual or potential leaks or spills of hazardous substances. Learn more
Hazardous materials specialist
A responder with specific knowledge of hazardous substances who supports technicians. At least 24 hours of technician-level training. Learn more
Hazardous materials technician
A responder who approaches the point of release to plug, patch or stop it. At least 24 hours of training. Learn more
HAZWOPER
Hazardous Waste Operations and Emergency Response, the OSHA standard at 29 CFR 1910.120 and 1926.65. Learn more
Heat stress
A dangerous rise in body temperature, common when wearing chemical protective clothing. Ranges from heat rash and cramps to heat exhaustion and heat stroke. Learn more
Hot line
The boundary that marks the outer edge of the exclusion zone. Learn more
ICS (incident command system)
A standardized organizational structure for managing an emergency response, required by 1910.120(q)(3). Learn more
IDLH
Immediately Dangerous to Life or Health: a concentration that could cause death or serious permanent harm or prevent escape. Learn more
Incident commander
The person in charge of the on-scene emergency response. Needs at least 24 hours of training equal to operations level plus competencies. Learn more
Ionization potential (IP)
The energy needed to ionize a molecule. A PID detects a chemical only if its lamp energy is higher than the chemical's IP. Learn more
LEL (lower explosive limit)
The lowest concentration of a gas or vapor in air that will burn or explode if ignited. Also called lower flammable limit (LFL). Learn more
Level A
The highest level of PPE: SCBA or supplied air plus a totally encapsulating, vapor-tight chemical suit. Learn more
Level B
PPE with the highest respiratory protection (SCBA or supplied air) and splash-protective, non-vapor-tight clothing. Learn more
Level C
PPE with an air-purifying respirator and chemical-resistant clothing, used when contaminants and concentrations are known. Learn more
Level D
A work uniform with no respiratory protection, for nuisance contamination only. Learn more
LQG (large quantity generator)
A site that generates 1,000 kg or more of hazardous waste, or more than 1 kg of acute hazardous waste, in a calendar month. Learn more
Manifest
The Uniform Hazardous Waste Manifest (EPA Form 8700-22) that tracks hazardous waste from generator to destination facility. Learn more
Medical surveillance
The program of medical exams HAZWOPER requires for workers exposed above limits, respirator users and HAZMAT team members. Learn more
Oxygen deficient atmosphere
Air with less than 19.5% oxygen by volume. Learn more
Oxygen enriched atmosphere
Air with more than 23.5% oxygen by volume, which increases fire risk. Learn more
PAPR
Powered air-purifying respirator: a blower forces air through filters into the facepiece or hood. Learn more
PEL (permissible exposure limit)
OSHA's legally enforceable airborne exposure limit, usually an 8-hour time-weighted average. Learn more
PID (photoionization detector)
An instrument that uses ultraviolet light to ionize and measure many volatile organic compounds. Learn more
PPE
Personal protective equipment: respirators, protective clothing, gloves, boots, eye and face protection. Learn more
RCRA
The Resource Conservation and Recovery Act, the federal law governing hazardous waste from generation to disposal. Learn more
Refresher training
The 8 hours of annual training HAZWOPER requires to keep 40 and 24 hour workers current. Learn more
SARA
The Superfund Amendments and Reauthorization Act of 1986, which directed OSHA to write the HAZWOPER standard. Learn more
Satellite accumulation area (SAA)
An area at or near the point of generation where up to 55 gallons of hazardous waste (or 1 quart/1 kg of acute) can be collected under operator control. Learn more
SCBA
Self-contained breathing apparatus: a respirator with its own air supply carried by the user. Used in Level A and B. Learn more
SDS (safety data sheet)
The document from the manufacturer that lists a chemical's hazards, exposure limits, PPE and emergency measures. Learn more
Site characterization
Evaluating a hazardous waste site before and during entry to identify hazards and select controls and PPE. Learn more
Site safety and health supervisor
The person responsible to the employer with authority to develop and carry out the site safety and health plan. Learn more
Skilled support personnel
Workers skilled in operating specific equipment, such as cranes or backhoes, who are needed temporarily during an emergency response. Learn more
SQG (small quantity generator)
A site that generates more than 100 kg but less than 1,000 kg of hazardous waste in a calendar month. Learn more
STEL (short-term exposure limit)
A 15-minute time-weighted average exposure that should not be exceeded at any time in the workday. Learn more
Supplied-air respirator (SAR)
A respirator that supplies breathing air through a hose from a remote source. Used with an escape bottle in IDLH conditions. Learn more
Support zone (SZ)
The clean, cold zone upwind of the exclusion zone, holding the command post, first aid and support equipment. Learn more
TLV (threshold limit value)
ACGIH's guideline exposure limit, updated yearly. Learn more
TSDF
Treatment, storage and disposal facility for hazardous waste, regulated under RCRA (40 CFR 264/265) and covered by HAZWOPER 1910.120(p). Learn more
TWA (time-weighted average)
The average exposure concentration over a work shift, usually 8 hours. Learn more
UEL (upper explosive limit)
The highest concentration of a gas or vapor in air that will burn. Above the UEL the mixture is too rich to burn. Learn more
Uncontrolled hazardous waste site
An area where hazardous substances have accumulated and pose a threat to people or the environment, such as Superfund sites and abandoned dumps. Learn more
Universal waste
Common hazardous wastes such as batteries, lamps, pesticides, mercury equipment and aerosol cans, managed under simpler rules at 40 CFR 273. Learn more
Vapor density
The weight of a vapor compared with air. Vapors with a density above 1 sink and collect in low areas. Learn more
VSQG (very small quantity generator)
A site that generates 100 kg or less of hazardous waste, and 1 kg or less of acute hazardous waste, in a calendar month. Learn more

This guide summarizes federal OSHA, Cal/OSHA and EPA rules for training purposes. It is not legal advice. Always check the current regulation text and your site safety and health plan.

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