# HAZWOPER Glossary: 71 Terms and Acronyms Explained

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

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](https://www.hazwoperosha.com/guides/site-control-work-zones/)
- **Acute exposure:** A single or short-term exposure to a substance, usually at a high concentration, with effects that appear quickly. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **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](https://www.hazwoperosha.com/guides/site-control-work-zones/)
- **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](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/what-is-hazwoper/)
- **CGI (combustible gas indicator):** An instrument that measures flammable gases and vapors as a percentage of the lower explosive limit (LEL). [Learn more](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/site-control-work-zones/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **Decontamination (decon):** Removing or neutralizing contaminants from people and equipment so hazards do not leave the work area. [Learn more](https://www.hazwoperosha.com/guides/hazwoper-decontamination/)
- **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](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **Exclusion zone (EZ):** The hot zone where contamination is or could be present. Entry requires the specified PPE. [Learn more](https://www.hazwoperosha.com/guides/site-control-work-zones/)
- **FID (flame ionization detector):** An instrument that detects organic vapors, including methane, by burning the sample in a hydrogen flame. [Learn more](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **Hazardous substance:** Under HAZWOPER, any substance designated under CERCLA, biological or disease-causing agents, DOT hazardous materials, and hazardous wastes. [Learn more](https://www.hazwoperosha.com/guides/what-is-hazwoper/)
- **Hazardous waste:** Waste listed by EPA or showing a hazardous characteristic: ignitability, corrosivity, reactivity or toxicity. [Learn more](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **HASP:** Health and safety plan: the site-specific safety and health plan required by 1910.120(b)(4). [Learn more](https://www.hazwoperosha.com/guides/site-safety-and-health-plan/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **Hazardous materials specialist:** A responder with specific knowledge of hazardous substances who supports technicians. At least 24 hours of technician-level training. [Learn more](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **HAZWOPER:** Hazardous Waste Operations and Emergency Response, the OSHA standard at 29 CFR 1910.120 and 1926.65. [Learn more](https://www.hazwoperosha.com/guides/what-is-hazwoper/)
- **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](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **Hot line:** The boundary that marks the outer edge of the exclusion zone. [Learn more](https://www.hazwoperosha.com/guides/site-control-work-zones/)
- **ICS (incident command system):** A standardized organizational structure for managing an emergency response, required by 1910.120(q)(3). [Learn more](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **IDLH:** Immediately Dangerous to Life or Health: a concentration that could cause death or serious permanent harm or prevent escape. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **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](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/air-monitoring/)
- **Level A:** The highest level of PPE: SCBA or supplied air plus a totally encapsulating, vapor-tight chemical suit. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **Level B:** PPE with the highest respiratory protection (SCBA or supplied air) and splash-protective, non-vapor-tight clothing. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **Level C:** PPE with an air-purifying respirator and chemical-resistant clothing, used when contaminants and concentrations are known. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **Level D:** A work uniform with no respiratory protection, for nuisance contamination only. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **Manifest:** The Uniform Hazardous Waste Manifest (EPA Form 8700-22) that tracks hazardous waste from generator to destination facility. [Learn more](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **Medical surveillance:** The program of medical exams HAZWOPER requires for workers exposed above limits, respirator users and HAZMAT team members. [Learn more](https://www.hazwoperosha.com/guides/hazwoper-medical-surveillance/)
- **Oxygen deficient atmosphere:** Air with less than 19.5% oxygen by volume. [Learn more](https://www.hazwoperosha.com/guides/air-monitoring/)
- **Oxygen enriched atmosphere:** Air with more than 23.5% oxygen by volume, which increases fire risk. [Learn more](https://www.hazwoperosha.com/guides/air-monitoring/)
- **PAPR:** Powered air-purifying respirator: a blower forces air through filters into the facepiece or hood. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **PEL (permissible exposure limit):** OSHA's legally enforceable airborne exposure limit, usually an 8-hour time-weighted average. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **PID (photoionization detector):** An instrument that uses ultraviolet light to ionize and measure many volatile organic compounds. [Learn more](https://www.hazwoperosha.com/guides/air-monitoring/)
- **PPE:** Personal protective equipment: respirators, protective clothing, gloves, boots, eye and face protection. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **RCRA:** The Resource Conservation and Recovery Act, the federal law governing hazardous waste from generation to disposal. [Learn more](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **REL (recommended exposure limit):** NIOSH's recommended exposure limit, often more protective than the OSHA PEL. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **Refresher training:** The 8 hours of annual training HAZWOPER requires to keep 40 and 24 hour workers current. [Learn more](https://www.hazwoperosha.com/guides/hazwoper-refresher-requirements/)
- **SARA:** The Superfund Amendments and Reauthorization Act of 1986, which directed OSHA to write the HAZWOPER standard. [Learn more](https://www.hazwoperosha.com/guides/what-is-hazwoper/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **SCBA:** Self-contained breathing apparatus: a respirator with its own air supply carried by the user. Used in Level A and B. [Learn more](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **SDS (safety data sheet):** The document from the manufacturer that lists a chemical's hazards, exposure limits, PPE and emergency measures. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **Site characterization:** Evaluating a hazardous waste site before and during entry to identify hazards and select controls and PPE. [Learn more](https://www.hazwoperosha.com/guides/site-safety-and-health-plan/)
- **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](https://www.hazwoperosha.com/guides/site-safety-and-health-plan/)
- **Skilled support personnel:** Workers skilled in operating specific equipment, such as cranes or backhoes, who are needed temporarily during an emergency response. [Learn more](https://www.hazwoperosha.com/guides/emergency-response-training-levels/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **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](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/ppe-levels-a-b-c-d/)
- **Support zone (SZ):** The clean, cold zone upwind of the exclusion zone, holding the command post, first aid and support equipment. [Learn more](https://www.hazwoperosha.com/guides/site-control-work-zones/)
- **TLV (threshold limit value):** ACGIH's guideline exposure limit, updated yearly. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **TWA (time-weighted average):** The average exposure concentration over a work shift, usually 8 hours. [Learn more](https://www.hazwoperosha.com/guides/exposure-limits-pel-tlv-idlh/)
- **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](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/what-is-hazwoper/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)
- **Vapor density:** The weight of a vapor compared with air. Vapors with a density above 1 sink and collect in low areas. [Learn more](https://www.hazwoperosha.com/guides/air-monitoring/)
- **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](https://www.hazwoperosha.com/guides/rcra-hazardous-waste-training-requirements/)

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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