Hierarchy of Hazard Controls: OSHA Guide & Examples

A loose electrical wire, an unguarded machine, or a chemical with harmful fumes might seem like separate workplace problems. But they have something in common: each one can put employees at risk if the hazard is not properly controlled.

On a construction site, for example, workers may face fall hazards, moving equipment, dust, noise, and electrical risks during a single shift. Simply reminding everyone to be careful is not enough. Employers need practical measures that prevent exposure wherever possible.

That is where the hierarchy of controls comes in.

The hierarchy gives employers a way to compare different safety solutions and decide which ones are likely to provide the strongest protection. Rather than starting with warning signs or protective equipment, it encourages them to look at whether a hazard can be removed, replaced, or physically isolated from workers.

The five levels are:

1. Elimination

2. Substitution

3. Engineering controls

4. Administrative controls

5. Personal protective equipment (PPE)

The order matters. A solution that removes a hazard entirely will generally provide more dependable protection than one that relies on employees remembering to follow a procedure or wear the correct equipment.

Understanding the hierarchy of controls OSHA discusses in its workplace safety resources can help employers make more informed decisions about preventing injuries and reducing exposure.

For an overview of prevention practices, see OSHA's official guidance on Hazard Prevention and Control.

What Is the Hierarchy of Controls?

The hierarchy of controls is a workplace safety framework that ranks methods of controlling hazards according to their effectiveness. It helps employers decide how to protect workers after identifying something that could cause an injury or illness.

Think about a machine with exposed moving parts. One option is to put up a warning sign telling employees to keep their hands away. Another is to install a fixed guard that physically prevents access to the dangerous parts. Both are safety measures, but they do not offer the same level of protection.

The hierarchy encourages employers to consider the stronger solution first.

The framework is widely associated with the National Institute for Occupational Safety and Health (NIOSH). It is also relevant to OSHA's broader approach to identifying workplace hazards and implementing effective controls.

Its central idea is straightforward: control the hazard as close to its source as reasonably possible. Do not rely on worker behavior alone when a more dependable solution is available.

Why Does the Hierarchy of Hazard Controls Matter?

Choosing the wrong control can leave workers exposed even when a company has a safety policy in place. A warning sign, for instance, cannot stop a machine from operating dangerously. Similarly, handing out gloves does not remove the chemical that employees are handling.

The hierarchy helps employers look beyond basic precautions.

It can help a workplace:

• Find ways to remove hazards instead of simply warning employees about them.

• Reduce exposure to harmful substances, noise, machinery, and other risks.

• Decide whether equipment or process changes could improve safety.

• Use training and work procedures where they are genuinely needed.

• Choose PPE that supports other safety measures.

• Build a more consistent approach to preventing workplace injuries.

Before choosing a control, employers need to understand what they are dealing with. OSHA's Hazard Identification and Assessment guidance provides information about recognizing and evaluating workplace hazards.

What Are the Five Levels of the Hierarchy of Controls?

The five levels are arranged from the control method that generally offers the strongest protection to the one that relies most heavily on individual workers.

Here is what each level means in everyday workplace situations.

1. Elimination: Remove the Hazard Completely

Elimination means getting rid of a hazard so workers no longer have to deal with it. Because the source of danger is removed, this is generally the most effective level of the hierarchy.

Consider a construction project where workers would normally need to access an elevated area to install a component. If the project can be redesigned so that the component is assembled at ground level, the need for that particular elevated task may disappear.

Other examples include:

• Removing damaged electrical equipment from service.

• Discontinuing an unnecessary task that exposes workers to a dangerous condition.

• Removing a hazardous material from a production process.

• Redesigning a job so employees do not need to work at a dangerous height.

• Taking an unsafe machine or tool out of use.

• Ordering lumber pre-cut to the required sizes so workers do not need to operate saws onsite.

• Redesigning warehouse routes so forklifts and pedestrians do not cross paths.

Elimination is often easiest to achieve during the planning and design stage of a project. For example, deciding how materials will be prepared or how vehicles and pedestrians will move around a warehouse before operations begin can prevent certain hazards from being created in the first place.

Elimination is not always possible. Some jobs involve risks that cannot realistically be removed without changing the entire process. Still, it is worth considering before moving down to the other control levels.

2. Substitution: Choose a Safer Alternative

Sometimes a hazard cannot be removed, but the material, equipment, or process creating it can be changed. That is the purpose of substitution.

For example, a facility might use a cleaning chemical that produces harmful fumes. If a less hazardous product can do the same job, replacing the original chemical may reduce the risk to employees.

Other substitution examples include:

• Replacing a highly toxic cleaning product with a less hazardous one.

• Using water-based paint instead of a solvent-based product when appropriate.

• Choosing equipment that produces less noise.

• Replacing a hazardous material with a safer alternative.

• Changing a production method to reduce harmful exposure.

There is one important point to remember: a replacement is not automatically safe just because it is marketed as a greener or safer option. Employers should compare the hazards of both products, review the safety data sheets, and consider whether the replacement introduces different risks.

OSHA offers information about Transitioning to Safer Chemicals that can help employers think through chemical substitutions.

Hazardous Materials and Chemical Safety

Chemical safety also involves understanding how hazardous substances are identified and handled. The risks can vary depending on the material, how it is used, and whether employees are exposed through breathing, skin contact, or another route.

Transportation classifications are another part of hazardous material awareness. Our guide to the nine DOT hazard classes explains how hazardous materials are grouped according to their transportation-related dangers.

Keep in mind that DOT hazard classes and the hierarchy of controls are not the same system. DOT classifications relate to hazardous materials during transportation, while the hierarchy helps employers decide how to control hazards in the workplace.

3. Engineering Controls: Keep Workers Away From the Hazard

Engineering controls involve changing equipment, machinery, or the physical work environment to reduce employee exposure. Instead of asking workers to avoid a hazard every time they perform a task, these controls create a physical barrier or change how the hazard reaches them.

A simple example is a guard installed over moving machine parts. Employees can operate the equipment without having direct access to the dangerous components.

Other engineering control examples include:

• Machine guards and safety interlocks.

• Local exhaust ventilation.

• General ventilation systems.

• Noise barriers and sound enclosures.

• Physical barriers around hazardous equipment.

• Automated material-handling systems.

• Enclosed processes that limit exposure to harmful substances.

• Guardrails along elevated walkways and exposed edges.

• Remote-operated or automated equipment that allows workers to stay away from dangerous operations.

Imagine employees working near a process that releases dust into the air. Providing masks may offer some protection, but a properly designed local exhaust system can capture dust close to where it is produced. That reduces the amount that spreads into the work area.

Engineering controls are particularly useful in construction, manufacturing, laboratories, and industrial workplaces.

These controls may require a higher upfront investment than signs, training, or other procedural measures. However, once properly installed and maintained, they can provide ongoing protection without depending as heavily on workers remembering to take specific actions every time. Over the long term, they may also help reduce exposure-related incidents, work interruptions, and associated costs.

For more information about protecting employees from machinery hazards, visit OSHA's Machine Guarding resource.

What Are Some Engineering Controls Examples?

The right engineering control depends on the hazard. A machine guard will not solve a ventilation problem, just as a noise enclosure will not address an electrical exposure.

These examples show how equipment design and physical changes can reduce exposure without depending entirely on employees changing their behavior.

4. Administrative Controls: Make the Work Safer Through Better Procedures

Not every hazard can be eliminated or controlled through equipment changes. In those situations, administrative controls can help reduce how often or how long workers are exposed.

These controls change the way work is organized and performed. They may involve training, schedules, access rules, written procedures, or workplace policies.

Common examples include:

• Training employees to recognize job-related hazards.

• Creating written safe work procedures.

• Rotating employees to limit exposure time.

• Posting warning signs and hazard labels.

• Restricting access to dangerous areas.

• Scheduling regular equipment inspections.

• Establishing safe operating instructions.

• Setting work-rest schedules.

• Preparing emergency response procedures.

• Establishing procedures for controlling hazardous energy during equipment servicing and maintenance.

For example, employees working in a noisy area may spend only part of their shift there, with other tasks assigned during the remaining time. This can reduce individual exposure, although it does not remove the noise itself.

Administrative controls are useful, but they have a limitation: they depend on people following the rules. A procedure cannot physically stop someone from reaching into an operating machine. That is why employers should consider stronger controls where practical.

What Are Administrative Controls in OSHA Safety Programs?

In an OSHA-related safety program, administrative controls are measures that reduce exposure by changing work practices and employee responsibilities.

A workplace might introduce a daily inspection routine, require specific training before employees operate equipment, or limit access to an area while maintenance is underway.

Lockout/Tagout (LOTO) is another important example of a work-practice and energy-control procedure. Before covered maintenance or servicing work begins, employees follow the applicable procedure to isolate hazardous energy sources, apply appropriate locks and tags, control stored energy, and verify that the equipment cannot start unexpectedly.

For example, a maintenance worker repairing a conveyor system must follow the relevant energy-control procedure before working on the equipment. This helps prevent unexpected machine startup and the release of hazardous energy.

You can learn more about the process in our detailed guide to Lockout/Tagout (LOTO) procedures and OSHA requirements.

LOTO procedures depend on employees following the correct steps and receiving appropriate training. They should be part of a broader safety program and work alongside other protective measures rather than being treated as a replacement for physical safeguards.

These steps can make a real difference, especially when combined with engineering controls. However, training and written procedures should not be treated as substitutes for removing or physically controlling a hazard when a stronger solution is available.

5. Personal Protective Equipment (PPE): Protect Employees From Remaining Risks

Personal protective equipment is usually the final level of the hierarchy. It includes equipment employees wear to reduce their exposure to hazards that remain after other controls have been considered.

On a construction site, this might mean hard hats, safety glasses, gloves, hearing protection, or high-visibility clothing. In other workplaces, employees may need respirators or chemical-resistant protective clothing.

Common PPE includes:

• Safety helmets and hard hats.

• Safety glasses and goggles.

• Hearing protection.

• Respirators.

• Protective gloves.

• High-visibility clothing.

• Safety footwear.

• Chemical-resistant protective clothing.

PPE is important, but handing out equipment is not enough. Employers need to select protection that matches the actual hazard and make sure workers know how to use it. Fit, maintenance, storage, and replacement also matter.

OSHA provides a Personal Protective Equipment Assessment resource for evaluating PPE needs.

Why Is PPE the Least Effective Control?

PPE is generally considered the least effective standalone level because it protects the person wearing it without removing the hazard.

For example, safety glasses can help protect an employee from flying particles, but they do not stop the machine from producing those particles. If the glasses are damaged, unsuitable, or worn incorrectly, the protection may also be reduced.

Some limitations of PPE include:

• It does not remove the source of danger.

• Employees may wear it incorrectly or inconsistently.

• Equipment can become damaged or worn out.

• It needs regular inspection and maintenance.

• The wrong type or fit may provide inadequate protection.

That does not mean PPE is unimportant. It often plays an essential role in workplace safety, particularly when other controls cannot remove every risk. The goal is to avoid relying on PPE as the only answer when more effective measures are available.

Hierarchy of Controls Pyramid: Which Control Comes First?

The hierarchy of controls is often illustrated as an inverted pyramid. Elimination sits at the top because it removes the hazard. PPE appears at the bottom because it offers personal protection without removing the source of danger.

The order is:

1. Elimination: Remove the hazard.

2. Substitution: Replace it with a safer alternative.

3. Engineering controls: Physically separate workers from the hazard.

4. Administrative controls: Change work practices and procedures.

5. PPE: Protect workers from remaining exposure.

The pyramid is a useful way to remember the order, but it should not be treated as a rule that only one control can be used at a time.

In real workplaces, employers often combine several methods. A machine might have a physical guard, restricted operating procedures, employee training, and suitable PPE requirements. The important thing is to consider the stronger controls first rather than jumping straight to the easiest option.

What Is the Difference Between OSHA and NIOSH Hierarchy of Controls?

OSHA and NIOSH both work to improve occupational safety and health in the United States, but they have different responsibilities.

OSHA, the Occupational Safety and Health Administration, is part of the U.S. Department of Labor. It establishes and enforces workplace safety and health requirements.

NIOSH, the National Institute for Occupational Safety and Health, is part of the Centers for Disease Control and Prevention (CDC). It conducts research and develops recommendations to prevent work-related injuries and illnesses.

The hierarchy of controls is widely associated with NIOSH's occupational safety guidance, which presents the five levels in order of general effectiveness. OSHA also recommends considering the hierarchy when employers identify hazards and choose prevention measures.

These are not competing systems. NIOSH provides research-based recommendations, while OSHA establishes and enforces workplace safety requirements. Both support the use of effective controls to prevent workplace injuries and illnesses.

In practical terms, OSHA's requirements help employers understand their workplace safety responsibilities, while NIOSH research and recommendations provide useful information about preventing occupational hazards.

Which Level of the Hierarchy of Controls Is Most Effective?

Elimination is generally the most effective control because it removes the hazard itself.

Suppose a production process uses a chemical that creates a serious exposure risk. If the process can be redesigned so that the chemical is no longer needed, employees no longer face that particular exposure.

That is a stronger solution than asking workers to wear additional protective equipment while continuing to use the chemical.

Of course, some hazards cannot be eliminated completely. Employers should assess the available options and select the strongest practical controls for the situation.

Which Level of the Hierarchy of Controls Is Least Effective?

PPE is generally the least effective standalone control in the hierarchy. It provides a protective barrier for individual employees, but the hazard remains in the workplace.

A respirator, for example, may help protect a worker from certain airborne contaminants when properly selected and used. However, it does not remove the contaminant from the work environment.

This is why employers should first consider whether the hazard can be eliminated, substituted, or controlled through engineering changes. PPE can then provide an additional layer of protection where needed.

How to Apply the Hierarchy of Controls in the Workplace

Knowing the five levels is one thing; using them effectively is another. Employers need to connect the framework to the actual tasks employees perform and the hazards they face.

A practical approach looks like this.

Step 1: Identify Workplace Hazards

Start by looking at the work itself. Walk through the site, observe employees performing their tasks, review equipment, and ask workers about problems they encounter.

Depending on the workplace, hazards may include:

• Exposed moving machine parts.

• Slippery floors.

• Damaged electrical equipment.

• Excessive noise.

• Chemical exposure.

• Working at heights.

• Poor ventilation.

Employees who perform the work every day may notice risks that are easy to miss during a quick inspection, so their feedback is valuable.

Step 2: Assess the Risk

After identifying a hazard, consider how it could cause harm.

Ask questions such as:

• How serious could an injury or illness be?

• How likely is exposure?

• How many employees could be affected?

• How frequently does the task take place?

• Are current safety measures working as intended?

This helps employers decide which hazards need attention and what type of control may be appropriate.

Step 3: Work Through the Five Control Levels

Do not immediately jump to warning signs or PPE. Consider the options in order:

• Can the hazard be removed?

• Can a safer material, tool, or process replace it?

• Can equipment or workplace design isolate employees from it?

• Can procedures or schedules reduce exposure?

• What PPE is needed for any remaining risk?

The answer will vary from one job to another. Some hazards may be eliminated, while others may require a combination of controls.

Step 4: Put the Controls Into Practice

Once a suitable approach has been selected, make the necessary changes.

This could involve purchasing safer materials, installing guards, improving ventilation, updating work procedures, training employees, or providing appropriate protective equipment.

Employees should understand what is changing and why the new measures matter.

Step 5: Check Whether the Controls Are Working

Installing a control does not mean the job is finished. Equipment can wear out, processes can change, and new hazards can appear.

Employers should inspect safety systems, review incidents and near misses, listen to employee feedback, and reassess risks whenever workplace conditions change.

If a control is not reducing exposure as expected, it may need to be adjusted or replaced.

Hierarchy of Controls Examples in Construction

Construction sites are a good example of why the hierarchy matters. Workers may move between tasks involving heights, machinery, electrical systems, dust, noise, and hazardous materials throughout the day.

The same control will not work for every situation. Employers need to look at the specific task and decide how the risk can best be reduced.

Consider a worker who needs to install a component at an elevated location. Before relying on fall protection equipment, the employer could examine whether the task can be completed at ground level. If that is not practical, appropriate physical protections and safe work procedures may be needed.

This is the practical value of the hierarchy: it encourages employers to look for better ways to perform the work, not just ways to protect employees after a hazard has already been created.

Common Mistakes When Using the Hierarchy of Controls

Even workplaces with established safety programs can make poor control decisions. Sometimes the easiest solution gets chosen before anyone considers whether a stronger option is available.

Common mistakes include:

• Providing PPE without first evaluating whether the hazard can be removed or isolated.

• Treating employee training as a replacement for necessary engineering controls.

• Switching to a substitute chemical without checking its hazards.

• Installing equipment without confirming that it actually reduces exposure.

• Failing to inspect and maintain guards, ventilation systems, and other controls.

• Overlooking feedback from employees who work directly with the hazard.

• Assuming one control method will solve every workplace safety problem.

The hierarchy is meant to guide decisions, not serve as a box-ticking exercise. Employers should understand the source of each hazard, compare possible solutions, and check whether the selected measures are effective.

Frequently Asked Questions About the Hierarchy of Controls

1. What are the five levels of the hierarchy of controls?

The five levels are elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE). They are generally ranked from the most effective to the least effective control method.

2. What is the hierarchy of controls in OSHA?

The hierarchy of controls is a workplace safety framework for prioritizing ways to remove or reduce hazards. OSHA safety resources discuss hazard prevention and effective controls, while NIOSH is widely associated with the five-level hierarchy.

3. What is the correct order of hazard controls?

The usual order is elimination, substitution, engineering controls, administrative controls, and PPE. Employers should consider stronger controls before relying mainly on procedures or personal protective equipment.

4. Which hazard control is the most effective?

Elimination is generally the most effective because it removes the hazard from the workplace or work process.

5. Which hazard control is the least effective?

PPE is generally the least effective standalone control because it does not remove the hazard and depends on employees using suitable equipment correctly and consistently.

6. What are examples of engineering controls?

Examples include machine guards, local exhaust ventilation, noise enclosures, physical barriers, guardrails, and automated equipment that separates workers from hazardous processes.

7. What are examples of administrative controls?

Examples include employee safety training, written procedures, job rotation, warning signs, restricted access, work schedules, regular safety inspections, and energy-control procedures such as Lockout/Tagout.

8. Why is PPE at the bottom of the hierarchy of controls?

PPE is at the bottom because it protects individual workers without removing the hazard. Its effectiveness also depends on proper selection, fit, maintenance, and consistent use.

9. What is the difference between engineering and administrative controls?

Engineering controls use physical changes to isolate workers from hazards or reduce exposure. Administrative controls change how, when, or where employees perform their work.

10. What is the difference between elimination and substitution?

Elimination removes a hazard completely. Substitution replaces a hazardous material, product, or process with a safer alternative, although the replacement may still carry some risk.

11. What are the three most effective levels of hazard control?

The three highest levels are elimination, substitution, and engineering controls. They generally provide stronger protection because they address hazards at or near their source.

12. Is the hierarchy of controls used in construction?

Yes. Construction employers can use the hierarchy to evaluate hazards involving falls, machinery, chemicals, electricity, noise, and other job-site risks.

13. What is the NIOSH hierarchy of controls?

The NIOSH hierarchy of controls is a framework that ranks hazard prevention methods by effectiveness. It includes elimination, substitution, engineering controls, administrative controls, and PPE.

14. Must employers use all five levels?

No. Employers should assess each hazard and select controls that are appropriate for the situation. They may combine several methods, but the hierarchy encourages them to consider more effective controls first.

Improve Your Workplace Safety Knowledge With OSHA Training

Understanding the hierarchy of controls is useful for anyone who wants to recognize workplace risks and make better safety decisions. It helps explain why removing a hazard is usually a better starting point than relying on warnings or protective equipment alone.

If you want to build your understanding of workplace safety, explore the online training resources at Get OSHA Courses.

Our OSHA 10-Hour Construction Training Course introduces construction workers to important safety topics and common job-site hazards. The course offers self-paced online learning and is designed for eligible students located in the United States.

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