Control measures are actions, devices, or procedures put in place to reduce or eliminate a hazard, whether in a workplace, a public health setting, or the environment. The concept applies broadly: anything designed to stand between a risk and the people it could harm counts as a control measure. In practice, control measures range from physically removing a danger to simply wearing protective gear, and the most effective approaches combine several layers of protection at once.
The Hierarchy of Controls
Safety professionals organize control measures into five levels, ranked from most to least effective. This ranking system, known as the hierarchy of controls, is the standard framework used by OSHA, NIOSH, and the CDC. The five levels are elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE).
The logic behind the ranking is straightforward: controls that remove a hazard entirely don’t depend on anyone remembering to follow a rule or wear a piece of equipment. The higher up the hierarchy you go, the less a control measure relies on human behavior, and the more reliably it works.
Elimination and Substitution
Elimination means getting rid of the hazard completely. If a particular chemical causes respiratory problems, you stop using it. If a task at height creates a fall risk, you redesign the workflow so the task happens at ground level. No hazard, no exposure, no injury.
Substitution replaces the hazard with something less dangerous. A factory might swap a toxic solvent for a water-based alternative, or a hospital might replace sharp scalpels with safer cutting devices. Both elimination and substitution are the most effective control measures because they address the root cause of the risk. They’re also the hardest to implement after a process or facility is already up and running, which is why they’re easiest to build in during the design phase.
Engineering Controls
Engineering controls physically isolate people from hazards. They modify equipment, workspaces, or processes so that a danger never reaches the worker. The key advantage is that once installed, they work continuously without requiring anyone to take action.
Common examples include:
- Ventilation systems that pull contaminated air away from workers, such as fume hoods in laboratories or local exhaust systems in welding shops
- Machine guards and shields that prevent contact with moving parts
- Guardrails around elevated platforms or open edges
- Noise enclosures around loud equipment
- Safety-engineered medical devices like needleless systems and self-sheathing scalpels
- Patient lifts that reduce the physical strain of moving people in healthcare settings
Because engineering controls are built into the physical environment, they protect everyone in the area automatically. A guardrail doesn’t care whether someone read the safety manual. That built-in reliability is what makes engineering controls more effective than the options below them on the hierarchy.
Administrative Controls
Administrative controls change the way work is organized, performed, or communicated. They don’t remove the hazard or block it physically. Instead, they reduce how often or how long people are exposed. These controls depend on people following procedures, which makes them less reliable than engineering solutions.
They include work process training, job rotation (so no single person is exposed to a hazard all day), scheduled rest breaks, limiting access to hazardous areas, adjusting production line speeds, and equipment inspection checklists. Warnings also fall into this category: safety signs, backup alarms, smoke detectors, labels, and color-coded instructions all give workers information to help them avoid harm.
Administrative controls are often used alongside higher-level measures. A factory might install a machine guard (engineering control) and also require lockout procedures before maintenance (administrative control). Layering controls this way creates redundancy, so if one measure fails, another still provides some protection.
Personal Protective Equipment
PPE is the last line of defense: gloves, respirators, hard hats, safety goggles, earplugs, high-visibility vests. It sits at the bottom of the hierarchy because it does nothing to reduce the hazard itself. If the equipment fits poorly, gets damaged, or isn’t worn correctly, the protection disappears entirely.
That said, PPE is sometimes the only practical option in the short term, or the necessary final layer when higher-level controls can’t reduce exposure to zero. Healthcare workers dealing with infectious patients, for example, rely on gowns, masks, and gloves even when engineering controls like isolation rooms and ventilation systems are already in place.
Control Measures in Public Health
Outside the workplace, control measures are central to managing infectious disease. Public health authorities use a parallel set of strategies to break chains of transmission. Screening travelers at border entry points catches potential cases early. Contact tracing and active surveillance identify who has been exposed. Quarantine and isolation physically separate sick or exposed individuals from the broader population. Vaccination programs eliminate susceptibility across entire communities.
In healthcare settings specifically, infection control measures include establishing designated isolation units, ensuring adequate supplies of PPE and disinfectant materials, and training staff on safe sample collection, storage, and transport. During outbreaks like Ebola, these measures are scaled up rapidly, with protocols covering everything from how specimens are deactivated to how family members of suspected cases are advised.
Control Measures for Environmental Hazards
Environmental control measures target pollution at the source, in transit, or at the point of exposure. The EPA’s preferred approach mirrors the workplace hierarchy: prevent pollution before it’s created. This can mean switching to less toxic raw materials, adopting cleaner industrial processes, or improving process efficiency so less waste is generated in the first place.
When pollution can’t be prevented entirely, capture and treatment technologies step in. For air pollution, these include mechanical collectors, wet scrubbers, fabric filters (sometimes called baghouses), and electrostatic precipitators that pull particles out of exhaust streams. For transportation-related emissions, control measures include tailpipe emission standards and requirements for cleaner fuels. Regulatory tools like emissions trading programs and caps on total emissions create economic incentives for companies to reduce pollution beyond what traditional regulations require.
Evaluating Whether Controls Actually Work
Implementing a control measure is only half the job. Regular testing and review are essential to confirm that a control is performing as intended. Without this step, organizations can operate for years under the assumption that a risk is managed when it isn’t.
Common methods for checking control effectiveness include spot checks, where someone watches a process being performed to verify it follows standard procedures, or randomly audits a sample of outputs for quality. Pressure testing examines controls from the perspective of someone trying to exploit them, which is particularly useful for fraud prevention. More formal assurance reviews evaluate whether controls align with internal policies and the broader risk management framework. Internal audits provide the most rigorous assessment, producing a documented report on control performance.
The people responsible for running a control day to day should be monitoring it informally and continuously. More structured reviews, led by internal auditors or dedicated risk teams, provide periodic independent verification. After each round of testing, findings feed back into the risk register so that weak or failing controls can be strengthened, replaced, or supplemented with additional layers of protection.