NIOSH SHO Hazard Control key terms

The process of predicting potential workplace hazards and exposures before a task, process, or new facility begins, using knowledge of materials, operations, and similar past situations to design prevention in early.

Systematic effort to recognize agents, conditions, or activities capable of causing harm, such as chemical, physical, biological, ergonomic, and safety hazards, so they can be evaluated and controlled.

The process of measuring or estimating the intensity, frequency, and duration of worker contact with a hazard, often comparing results to occupational exposure limits to judge risk.

A structured observational visit of the workplace to observe processes, materials, work practices, and controls, and to identify hazards and conditions requiring further evaluation.

A method that breaks a job into steps, identifies hazards in each step, and specifies controls, often documented to guide training and safe work procedures.

A group of workers judged to share similar exposure profiles because they perform comparable tasks with comparable materials and controls, allowing representative sampling rather than sampling every worker.

A ranked framework for selecting controls, generally from most to least effective: elimination, substitution, engineering controls, administrative controls, and personal protective equipment.

Removing a hazard entirely by discontinuing a process, material, or task, which is the most reliable control because no residual exposure remains to manage.

Replacing a hazardous material, process, or equipment with a less hazardous alternative, such as a safer solvent, while verifying the replacement does not introduce new risk.

Physical changes to the workplace or process, such as ventilation, enclosure, isolation, or automation, that reduce exposure at the source without relying on worker behavior.

Work policies and practices that reduce exposure by changing how or when work is done, such as rotation, scheduling, training, and limiting time in hazardous areas.

Devices worn by workers, such as respirators, gloves, and eye protection, that reduce exposure at the individual level and are considered the last line of defense.

A system that captures airborne contaminants near their source using hoods, ducts, and a fan, then removes them before they enter the worker's breathing zone.

The air speed required at the point of contaminant release to draw the contaminant into a hood, typically highest for open processes and lower for enclosed or canopy hoods.

General ventilation that mixes clean air with contaminated workplace air to lower contaminant concentration, suitable only when contaminant generation is relatively uniform and low toxicity.

Separating workers from a hazard using distance, barriers, enclosures, or time scheduling, so exposure is prevented without changing the underlying process.

A physical barrier or closed system around a hazardous process or material that prevents release into the work area, often combined with exhaust to control fugitive emissions.

A specific way of performing a task that reduces exposure, such as keeping the face away from the source, cleaning spills promptly, or avoiding dry sweeping of dust.

A written, task-specific sequence of steps and precautions that workers follow to perform work safely, usually developed from a job hazard analysis and reinforced by training.

An administrative practice of moving workers among tasks to limit the duration of exposure to a hazard, reducing cumulative dose but not eliminating the hazard itself.

A procedure that checks whether a tight-fitting respirator seals against a worker's face, performed qualitatively or quantitatively before use and periodically thereafter.

The expected level of protection a properly functioning respirator class provides to a specified percentage of wearers, used to select a respirator for a measured exposure concentration.

Choosing a respirator type based on hazard identity, exposure concentration relative to exposure limits, assigned protection factor, and conditions such as oxygen deficiency or eye irritation.

A regulatory or advisory airborne concentration intended to protect workers from adverse health effects, often expressed as a time-weighted average, ceiling, or short-term limit.

Checking that installed controls actually function as intended, such as measuring hood airflow, testing alarms, or confirming that exposure is reduced after implementation.

Ongoing periodic checks of control performance over time, such as airflow gauges, maintenance records, and visual inspections, to detect degradation before exposure increases.

Scheduled servicing and inspection of control equipment, such as fans, filters, and guards, to keep performance within design specifications and prevent unexpected failure.

Collecting air or other samples from the worker's breathing zone with a wearable device, producing an exposure estimate that reflects the individual's actual work activities.

The air speed measured across the opening of a local exhaust hood, a common verification measurement used to confirm the system is drawing air as designed.

Structured instruction that gives workers the knowledge and skills to recognize hazards and follow controls, effective only when reinforced by practice and supervision.

A documented program that sets out identified hazards, selected controls, responsibilities, verification methods, and review schedules for a facility or process.

The degree of certainty that sampling results represent the exposure of a group, influenced by sample size, variability, and sampling strategy, and used when interpreting exposure data.

Building-wide air supply and exhaust intended to maintain air quality and comfort, which can supplement but rarely substitute for source-specific controls for toxic contaminants.

Periodic review of whether a hazard control program meets its objectives, using exposure data, verification records, incident trends, and worker feedback to guide improvements.