OSHA Safety Glossary

Abatement: The correction of a cited OSHA violation. When OSHA issues a citation, it includes an abatement date by which the employer must correct the hazard. Proof of abatement must be submitted to OSHA as documentation.
Abatement Date: The deadline specified in an OSHA citation by which a cited violation must be corrected. Missing an abatement date results in Failure to Abate penalties of up to $16,550 per day.
Action Level: A concentration of airborne contaminant below the permissible exposure limit that triggers additional obligations such as air monitoring, medical surveillance, or training. For example, the action level for noise is 85 dBA, which triggers hearing conservation program requirements.
Administrative Controls: Work practices or procedures that reduce worker exposure to hazards by changing how or when work is done. Examples include job rotation to limit repetitive motion exposure, scheduling heavy outdoor work during cooler parts of the day, and establishing written safe operating procedures.
Air-Purifying Respirator (APR): A respirator that removes contaminants from ambient air by passing it through a filter, cartridge, or canister before the worker inhales it. APRs cannot be used in oxygen-deficient atmospheres or IDLH conditions.
ANSI: American National Standards Institute. A private organization that coordinates development of voluntary consensus standards for safety equipment and procedures. Many OSHA standards reference ANSI standards (e.g., ANSI Z87.1 for eye protection, ANSI Z89.1 for hard hats).
Assigned Protection Factor (APF): The level of protection a respirator is expected to provide when properly fitted and used. A half facepiece has an APF of 10, meaning it reduces airborne concentration to 1/10th of ambient levels when properly worn.
Attendant: In confined space entry, the person stationed outside the permit space who maintains communication with entrants, monitors conditions, and has authority to order evacuation. The attendant must never enter the space.
Authorized Employee: In lockout/tagout, an employee who locks out or tags out machines or equipment in order to perform servicing or maintenance. Distinguished from affected employees, who operate the equipment.

Bloodborne Pathogens: Pathogenic microorganisms present in human blood and other potentially infectious materials (OPIM) that can cause disease. OSHA's Bloodborne Pathogen Standard (29 CFR 1910.1030) requires exposure control plans, training, and other protections for workers with occupational exposure.
Body Belt: A safety belt worn around the waist. Body belts may be used for positioning and restraint but are not permitted as the sole means of fall arrest — they can cause severe internal injuries during a fall. A full-body harness is required for fall arrest.

CFR: Code of Federal Regulations. The compilation of permanent rules published by federal agencies. OSHA standards are found in Title 29 of the CFR — general industry in Part 1910, construction in Part 1926, agriculture in Part 1928.
Competent Person: A person designated by the employer as capable of identifying existing and predictable hazards in the surroundings or working conditions that are unsanitary, hazardous, or dangerous to workers, and who has the authority to take prompt corrective measures to eliminate them.
Confined Space: A space large enough for a worker to enter, with limited or restricted entry or exit, and not designed for continuous occupancy. Examples include tanks, silos, manholes, and certain excavations. See: Confined Space Guide.
Contaminant: Any harmful, irritating, or nuisance material that is foreign to the normal composition of an atmosphere. Includes dusts, fumes, mists, vapors, gases, smoke, and biological agents.
Corrective Action: Steps taken to eliminate or control a hazard identified through an inspection, incident investigation, or employee report. Documentation of corrective actions is important evidence of good faith in OSHA proceedings.

De Minimis Violation: A technical violation of an OSHA standard that has no direct or immediate relationship to safety or health. OSHA may issue a de minimis notice rather than a citation and does not propose a penalty for de minimis violations.
Decibel (dB / dBA): The unit used to measure sound intensity. OSHA's noise standard uses the A-weighted decibel (dBA) scale, which approximates the human ear's sensitivity. The permissible exposure limit (PEL) for noise is 90 dBA as an 8-hour TWA; the action level is 85 dBA.

Emergency Action Plan (EAP): A written plan required by OSHA (29 CFR 1910.38) describing the actions employers and employees must take to ensure employee safety in fire or other emergencies. Must cover evacuation procedures, alarm systems, and employee accounting.
Employer of Record: The entity legally responsible for a worker's employment, including OSHA compliance obligations. On multi-employer worksites, determining the employer of record affects which employer can be cited for specific violations.
Energy Control Program: The written program required by OSHA's Lockout/Tagout standard (29 CFR 1910.147) describing the procedures an employer uses to prevent unexpected energization of equipment during servicing and maintenance.
Engineering Controls: Physical modifications to a work environment or process that eliminate or reduce exposure to hazards. Examples include ventilation systems, machine guards, noise enclosures, and substitution of less hazardous materials. Engineering controls are preferred over administrative controls or PPE.
Entry Permit: The written authorization required before any worker enters a permit-required confined space. Must include hazard identification, atmospheric test results, acceptable entry conditions, rescue procedures, and entry supervisor signature.
Exposure Control Plan: The written plan required by OSHA's Bloodborne Pathogen Standard (29 CFR 1910.1030) describing how an employer will protect workers from occupational exposure to bloodborne pathogens. Must be updated annually and reviewed after any exposure incident.

Failure to Abate: An OSHA violation category for an employer who fails to correct a previously cited violation by the abatement date. Penalties can reach $16,550 per day the violation continues beyond the abatement date.
Fatal Four: OSHA's term for the four hazards responsible for the most construction worker fatalities: falls, struck-by incidents, caught-in/between incidents, and electrocution. Together they account for roughly 60% of construction deaths.
Fit Testing: The process used to verify that a particular tight-fitting respirator properly seals against a specific worker's face. Required before initial use of any tight-fitting respirator and annually thereafter. Two methods: qualitative (using the wearer's sense of smell or taste) and quantitative (using instruments to measure actual seal leakage).
Flash Point: The lowest temperature at which a liquid produces enough vapor to ignite in air when an ignition source is present. Flammable liquids (flash point below 100°F) require special storage and handling procedures.
Fume: Solid particles generated by condensation from the gaseous state, generally after volatilization from molten metals. Welding fumes are a common occupational exposure concern — many are toxic and some are carcinogenic.

General Duty Clause: Section 5(a)(1) of the OSH Act, requiring every employer to furnish a place of employment free from recognized hazards likely to cause death or serious physical harm. OSHA uses this clause to cite hazards not addressed by a specific standard.
GHS: Globally Harmonized System of Classification and Labelling of Chemicals. An international framework for classifying chemicals and communicating hazard information through standardized labels and Safety Data Sheets. OSHA adopted GHS in 2012 through its revised HazCom standard.
Good Faith: In the context of OSHA penalties, an employer's genuine effort to comply with safety and health requirements. Documented safety programs, regular inspections, and prompt correction of identified hazards are evidence of good faith and can reduce proposed penalty amounts by up to 25%.
Guardrail System: A barrier consisting of a top rail, mid rail, and posts erected to prevent workers from falling from elevated work surfaces. OSHA requires top rails to be 42 inches (±3 inches) above the walking/working surface and capable of withstanding 200 pounds of force.

Hazard Communication (HazCom): OSHA's standard (29 CFR 1910.1200) requiring employers to identify and communicate chemical hazards to workers through written programs, Safety Data Sheets, container labels, and training. The most-cited general industry standard. See: HazCom Guide.
Hierarchy of Controls: A ranked approach to hazard control: (1) Elimination, (2) Substitution, (3) Engineering controls, (4) Administrative controls, (5) Personal protective equipment. Higher-ranked controls are more effective and preferred over lower-ranked ones.
Hot Work: Work that involves open flames, sparks, or heat sufficient to cause ignition of flammable or combustible materials. Includes welding, cutting, brazing, grinding, and similar operations. Typically requires a hot work permit system in facilities with flammable materials.

IDLH: Immediately Dangerous to Life or Health. An atmospheric concentration of any toxic, corrosive, or asphyxiating substance that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape. Air-purifying respirators cannot be used in IDLH atmospheres — supplied air or SCBA is required.
Incident Rate: A mathematical calculation that describes the number of recordable injuries or illnesses per 100 full-time workers per year. Used by OSHA to compare injury rates across employers and industries and to target programmed inspections.
Informal Conference: A meeting between an employer and the OSHA Area Director to discuss a citation before the formal contest deadline. Not a legal proceeding — an opportunity to negotiate penalty reductions, reclassifications, or withdrawals. Should be the first step for most employers after receiving a citation.
Injury and Illness Prevention Program (IIPP): A written safety program required by several state OSHA plans (notably California's Cal/OSHA) that addresses hazard identification, communication, correction, and ongoing safety management. Not currently required by federal OSHA but considered best practice.

LEL: Lower Explosive Limit (also called Lower Flammable Limit). The minimum concentration of a flammable gas or vapor in air below which the mixture will not ignite. OSHA generally requires entry into permit spaces to be halted when flammable gas concentrations reach 10% of LEL.
Lockout/Tagout (LOTO): Energy control procedures required by 29 CFR 1910.147 to prevent the unexpected energization, startup, or release of stored energy from machinery during servicing and maintenance. Involves physically locking energy isolating devices in the off position and verifying de-energization before work begins. See: LOTO Guide.

Material Safety Data Sheet (MSDS): The predecessor to the Safety Data Sheet (SDS) under the old HazCom standard. MSDS did not have a standardized format. OSHA's adoption of GHS replaced MSDS with the standardized 16-section SDS format. MSDS are no longer acceptable — SDS are required.
Multi-Employer Worksite: A worksite where workers of different employers are present simultaneously. OSHA's multi-employer worksite policy allows multiple employers to be cited for the same hazard based on their role as creating, exposing, controlling, or correcting employer.
Musculoskeletal Disorder (MSD): An injury or disorder affecting muscles, nerves, tendons, ligaments, joints, cartilage, or spinal discs. MSDs are the most common category of workplace injury and are frequently caused by ergonomic hazards including repetitive motion, forceful exertion, and awkward postures.

National Emphasis Program (NEP): An OSHA initiative that directs inspection resources toward specific high-hazard industries or hazards for a defined period. Active NEPs significantly increase the probability of inspection for targeted employers.
Near Miss: An unplanned event that did not result in injury, illness, or property damage but had the potential to do so. Near misses should be reported and investigated — they are early warnings of conditions that will eventually cause a serious incident if not corrected.
Notice of Contest: A written notification filed by an employer with the OSHA Area Director within 15 working days of receiving a citation, indicating the employer is challenging the citation, penalty, or abatement date. Filing a Notice of Contest initiates a proceeding before the Occupational Safety and Health Review Commission (OSHRC).
NRR: Noise Reduction Rating. A number assigned to hearing protection devices indicating the level of noise reduction provided under ideal laboratory conditions. Real-world protection is typically about half the labeled NRR. Used to select appropriate hearing protection for specific noise exposure levels.

Occupational Safety and Health Administration (OSHA): A federal agency within the U.S. Department of Labor responsible for setting and enforcing workplace safety and health standards. Created by the Occupational Safety and Health Act of 1970.
OSHRC: Occupational Safety and Health Review Commission. An independent federal agency that handles contested OSHA citations. When an employer files a Notice of Contest, the case is docketed with OSHRC for resolution through hearings or settlement.
Other-than-Serious Violation: An OSHA violation that has a direct relationship to job safety and health but would not likely cause death or serious physical harm. Penalties may be proposed up to $16,550 but are often significantly lower or zero for small employers with good faith.

PEL: Permissible Exposure Limit. The maximum concentration of an airborne contaminant to which a worker may be exposed over an 8-hour workday without adverse health effects. PELs are established by OSHA in 29 CFR 1910.1000. Many OSHA PELs are considered outdated — ACGIH TLVs and NIOSH RELs are often more protective.
Permit-Required Confined Space: A confined space that has one or more characteristics posing a serious safety or health hazard: potential for hazardous atmospheres, engulfment hazard, internal configuration hazard, or any other recognized serious hazard. Requires a permit system before entry.
Personal Fall Arrest System (PFAS): A system used to arrest a worker in a fall from a working level. Components include a full-body harness, lanyard or self-retracting lifeline, and anchor point rated for at least 5,000 pounds per attached worker.
Personal Protective Equipment (PPE): Equipment worn or used by workers to protect against workplace hazards. Includes hard hats, safety glasses, hearing protection, gloves, safety shoes, respirators, and fall arrest systems. PPE is the last line of defense in the hierarchy of controls and must be provided at no cost to the employee in most cases.
Pictogram: A standardized symbol used on GHS chemical labels to communicate hazard categories. OSHA's HazCom standard requires nine specific GHS pictograms including the flame, skull and crossbones, corrosion symbol, and health hazard symbol.
Powered Industrial Truck (PIT): OSHA's term for forklifts and similar motorized material handling equipment. Governed by 29 CFR 1910.178, which requires operator training and evaluation, daily pre-operation inspection, and specific safe operating procedures.

Qualified Person: A person who, by possession of a recognized degree, certificate, professional standing, or extensive knowledge, training, and experience, has successfully demonstrated the ability to solve problems relating to the subject matter, work, or project. Distinguished from "competent person" — a qualified person may have more formal credentials but the competent person has the on-site authority to take corrective action.

Recordable Incident: A work-related injury or illness that meets OSHA's recording criteria: results in days away from work, restricted work, job transfer, medical treatment beyond first aid, loss of consciousness, or diagnosis of a significant condition. Must be recorded on OSHA Form 300 within 7 days of notification.
Repeated Violation: A violation of any OSHA standard where the employer has been previously cited for the same or substantially similar violation within the past five years. Carries maximum penalties of $165,514 per violation — the same as willful violations.
ROPS: Rollover Protective Structure. A cab or frame structure on tractors and some construction equipment designed to protect the operator in the event of a rollover. Required by OSHA for agricultural tractors manufactured after October 25, 1976.

Safety Data Sheet (SDS): A standardized 16-section document providing detailed information about a hazardous chemical's properties, hazards, safe handling procedures, and emergency response information. Required by OSHA's HazCom standard (29 CFR 1910.1200) for every hazardous chemical in the workplace. Replaced the older MSDS format when OSHA adopted GHS.
Serious Violation: An OSHA violation where there is substantial probability that death or serious physical harm could result, and the employer knew or should have known of the hazard. OSHA must propose a penalty for serious violations. Maximum penalty is $16,550 per violation.
Signal Word: A word on a GHS-compliant chemical label that indicates the relative level of severity of the hazard. "Danger" indicates more severe hazards; "Warning" indicates less severe hazards. All GHS-classified hazardous chemicals must carry one of these signal words.
State Plan State: A state that has OSHA approval to operate its own occupational safety and health program. State Plans must be at least as effective as federal OSHA and may exceed federal requirements. 22 states and territories currently operate State Plans.
Struck-By Hazard: One of the Fatal Four construction hazards. A struck-by incident occurs when a worker is hit by a moving object — a vehicle, falling tool, swinging equipment, or flying debris. One of the leading causes of construction fatalities.
Subpart: A section of an OSHA standard organized by topic. For example, 29 CFR 1910 Subpart I covers Personal Protective Equipment, Subpart H covers Hazardous Materials, and Subpart S covers Electrical standards in general industry.

Tagout: A lockout/tagout method in which a tag is placed on an energy isolating device to warn that the equipment may not be operated. Tagout is only permitted when the isolating device cannot accept a lock. Additional protective measures must be used with tagout to achieve a level of protection equivalent to lockout.
TLV: Threshold Limit Value. Occupational exposure guidelines developed by the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs are not OSHA standards but are widely used by industrial hygienists and are generally more current and more protective than OSHA PELs.
Toolbox Talk: A short, informal safety meeting — typically 5–15 minutes — conducted at the job site before a shift or specific task. Toolbox talks are used to address specific hazards, reinforce safe work practices, and document ongoing safety communication. See: Free Toolbox Talk Topics.
TWA: Time-Weighted Average. The average exposure to an airborne contaminant over a specific time period, typically an 8-hour workday. OSHA PELs and many other exposure limits are expressed as 8-hour TWAs.

Unconfined Aquifer: Not an OSHA term — if you're looking for OSHA terms starting with U, see: Unqualified Person.
Unqualified Person: In electrical safety, a worker who has not received the training required to work safely on or near energized electrical conductors. Unqualified persons must maintain approach boundaries established by NFPA 70E and may not cross the limited approach boundary without continuous escort by a qualified person.

Vapor: The gaseous form of a substance that is normally liquid or solid at room temperature. Many solvents and flammable liquids emit vapors that can accumulate in enclosed spaces and create fire, explosion, or health hazards. Monitoring and ventilation are critical controls for vapor hazards.
Variance: An employer's formal request to OSHA for permission to use a different standard or method of compliance than what the applicable OSHA standard requires. Temporary variances may be granted while an employer installs required equipment or trains workers. Permanent variances require showing that the alternative provides equivalent or greater protection.

Walking-Working Surface: Any horizontal or vertical surface on or through which an employee walks, works, or gains access. OSHA's walking-working surfaces standard (29 CFR 1910 Subpart D) covers floors, aisles, stairways, ladders, dockboards, and similar surfaces in general industry.
Willful Violation: An OSHA violation committed with intentional disregard for, or plain indifference to, the requirements of the OSH Act. Carries maximum penalties of $165,514 per violation. If a worker dies as a result of a willful violation, criminal referral is possible. Willful violations indicate OSHA believes the employer knew about the hazard and chose not to address it.
Work-Related: An injury or illness is work-related if an event or exposure in the work environment caused or contributed to the condition or significantly aggravated a pre-existing condition. Work-relatedness is required for OSHA recordkeeping. Certain situations — personal tasks, common colds, injuries during commuting — are specifically excluded from work-relatedness.
Written Program: A documented set of procedures, policies, and practices required by specific OSHA standards. Common required written programs include the Hazard Communication Program, Energy Control (LOTO) Program, Respiratory Protection Program, and Emergency Action Plan. Written programs must be made available to workers and to OSHA on request.

Now You Know the Terms — Know the Requirements