Course 600 - Introduction to Occupational Safety and Health

Safety guides and audits to make your job as a safety professional easier

Hazard Controls


As you learned earlier, there are many different types of hazards in the workplace. Hazardous conditions include unsafe materials, equipment, the environment, and employees. Unsafe work practices include: allowing untrained workers to perform hazardous tasks, taking unsafe shortcuts, horseplay, or long work schedules. To combat these hazardous conditions and unsafe work practices, control strategies, called the "Hierarchy of Controls" have been developed.

Traditionally, a hierarchy of controls has been used as a means of determining how to implement feasible and effective controls. ANSI Z10-2005, Occupational Health and Safety Management Systems, encourages employers to employ the following five hazard control strategies:

  1. Elimination
  2. Substitution
  3. Engineering controls
  4. Administrative controls
  5. Personal protective equipment

The idea behind this hierarchy is that the control methods at the top of the list are potentially more effective and protective than those at the bottom. Following the hierarchy normally leads to the implementation of inherently safer systems, ones where the risk of illness or injury has been substantially reduced. Let's take a closer look at the hierarchy of control strategies.

What are "feasible" controls?

Hazard abatement (reduction) measures required to correct a hazard must be technologically and economically feasible (reasonable) for the employer. OSHA uses the following criteria to determine feasibility of engineering and administrative controls:

  • Technical Feasibility. Technical feasibility is the existence of technical know-how as to materials and methods available or adaptable to specific circumstances which can be applied with a reasonable possibility that employee exposure to hazards will be reduced.
  • Economic Feasibility. Economic feasibility means that the employer is financially able to undertake the measures necessary to abate identified hazards. Economic feasibility is a major issue to be considered when imposing hazard controls. OSHA may allow the use of PPE to abate a hazard, at least until such time as engineering controls become a less significant economic burden for the company when the following conditions are met:
    1. If significant reconstruction of a single establishment involving a capital expenditure which would seriously jeopardize the financial condition of the company is the only method whereby the employer could achieve effective engineering controls;
    2. If there are no feasible administrative or work practice controls; and
    3. If adequate personal protective equipment or devices are available.

Elimination and Substitution

Elimination and substitution, while most effective at reducing hazards, also tend to be the most difficult to implement in an existing process. If the process is still at the design or development stage, elimination and substitution of hazards may be inexpensive and simple to implement. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard.

Safety professionals consider these strategies first because they can completely eliminate the hazard. Eliminating the hazard will also eliminate the possibility of exposure to the hazard.

Some examples of these two strategies include:

  • Eliminating the source of excessive temperatures, noise, or pressure
  • Substituting a toxic chemical with a less toxic or non-toxic chemical

Engineering Controls

These controls focus on designing or redesigning the source of the hazard. Engineering controls are used to design or redesign the work environment to eliminate or reduce both the hazard, itself, and exposure to hazard. Just because this strategy is called "engineering" controls, it does not mean an engineer must design the control measure.

Some examples of this strategy include:

  • designing equipment to run more quietly
  • designing a work station to relieve physical stress and remove ergonomic hazards
  • designing general ventilation with sufficient fresh outdoor air to improve indoor air quality and generally to provide a safe, healthful atmosphere
  • ensure adequate lighting is installed for the environment and tasks performed

Redesigning or replacing equipment or machinery may be expensive, but remember, according to the National Safety Council, the direct and indirect costs of a lost work-time injury can be more than $70,000 and $1 million for fatality. The potential to save money in the long-term is great.

Enclosure of Hazards

When you cannot remove a hazard and cannot replace it with a less hazardous alternative, the next best control is enclosure. Enclosing a hazard usually means that there is no hazard exposure to workers during normal operations. There still will be potential exposure to workers during maintenance operations or if the enclosure system breaks down. For those situations, additional controls such as safe work practices or personal protective equipment (PPE) may be necessary to control exposure.

Some examples of enclosure designs are:

  • complete enclosure of moving parts of machinery
  • complete containment of toxic liquids or gases from the beginning to end of a process
  • glove box operations to enclose work with dangerous microorganisms, radioisotopes, or toxic substances
  • complete containment of noise, heat, or pressure producing processes with materials especially designed for those purposes

Barriers or Local Ventilation

A ventilation system with gaurds surrounding the fans
This is a good example of a barrier to prevent exposure.
(Click to Enlarge)

When the potential hazard cannot be removed, replaced, or enclosed, the next best approach is a barrier to exposure or, in the case of air contaminants, local exhaust ventilation to remove the contaminant from the workplace. This engineered control involves potential exposure to the worker even in normal operations. Consequently, it should be used only in conjunction with other types of controls, such as safe work practices designed specifically for the site condition and/or PPE. Examples include:

  • ventilation hoods in laboratory work
  • machine guarding, including electronic barriers
  • isolation of a process in an area away from workers
  • baffles used as noise-absorbing barriers
  • nuclear radiation or heat shields.

Administrative Controls

Administrative controls are aimed at reducing employee exposure to hazards that engineering controls fail to eliminate. Administrative controls work by designing safe work practices into job procedures and adjusting work schedules. Ultimately, effective administrative controls will successfully eliminate the human behaviors that result in 95% of all workplace accidents! Administrative controls are only as effective as the safety management system that supports them. It's always better to eliminate the hazard so that you don't have to rely on management controls that tend to work only as long as employees behave.

Safe work practices

Forklift lifting another Forklift
Safe work practices?
(Click to Enlarge)

Safe work practices may be quite specific or general in their applicability. They may be a very important part of a single job procedure or applicable to many jobs in the workplace. Safe work practices include:

  • removing tripping, blocking, and slipping hazards
  • removing accumulated toxic dust on surfaces
  • wetting down surfaces to keep toxic dust out of the air
  • using safe lifting techniques
  • maintaining equipment and tools in good repair
  • using personal protective equipment (PPE)

Other safe work practices apply to specific jobs in the workplace and involve specific procedures for accomplishing a job. A training program may be essential if employees are working with highly toxic substances or in dangerous situations.

Interim Measures

When a hazard is recognized, the preferred correction or control cannot always be accomplished immediately. However, in virtually all situations, interim measures can be taken to eliminate or reduce worker risk. These can range from taping down wires that pose a tripping hazard to actually shutting down an operation temporarily.

The importance of taking these interim protective actions cannot be overemphasized. There is no way to predict when a hazard will cause serious harm, and no justification to continue exposing workers unnecessarily to risk. By the way, OSHA believes there is always some kind of interim measure that can be used to temporarily abate a hazard.

Personal Protective Equipment (PPE)

types of PPE
Personal Protective Equipment

Using personal protective equipment is a very important safe work practice. It's important to remember that, like other administrative controls, the use of PPE does not control the hazard itself, but rather it merely controls exposure to the hazard by setting up a barrier between the employee and the hazard. Use of PPE may also be appropriate for controlling hazards while engineering controls being installed or work practices developed.

The hierarchy of controls is the standard system of strategies to effectively eliminate workplace hazards. Remember, the first question to ask when considering ways to eliminate a hazard is, "can we apply engineering controls?" You may need to use a combination of strategies to effectively eliminate the hazard. Whatever it takes, do it. You are not just saving a are saving a father, a mother, a son, or a are saving a family. It's worth the effort!

Hazard Controls

Machine Guarding


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Removing the source of excessive temperatures, noise or pressure is an example of _____.

2. Redesigning a piece of equipment so that it is not so noisy when operating is an example of _____.

3. Changing the work schedule so that workers have reduced exposure to noisy equipment is an example of _____.

4. Using ear plugs (PPE) when working around noisy equipment is an example of _____.

5. If a hazard exists, what action should be taken immediately?

Have a great day!

Important! You will receive an "error" message unless all questions are answered.