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Controlling Laboratory Hazards

Hierarchy of Control
Hierarchy of Controls
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The Hierarchy of Controls

There are many different types of hazards in the lab. Hazards are generally categorized into two types: 1) hazardous conditions and 2) unsafe work practices/behaviors.

  • Hazardous conditions include unsafe materials, equipment, environment and employees.
  • Unsafe work practices and behaviors 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.

The hierarchy of controls prioritizes intervention strategies based on the premise that the best way to control a hazard is to systematically remove it from the workplace, rather than relying on workers to reduce their exposure. The types of measures that may be used to protect laboratory workers, prioritized from the most effective to least effective, are:

  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.

  • The first three methods eliminate or reduce the hazard itself.
  • The last two methods attempt to control exposure to the hazard.

Following the hierarchy normally leads to the implementation of inherently safer systems, ones where the risk of illness or injury have been substantially reduced. Let's take a closer look at the hierarchy of control strategies.

Elimination and Substitution

Eliminate the Hazard – Napo

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.

These strategies are considered first because they have the potential of completely eliminating the hazard, thus greatly reducing the probability of an accident. Redesigning or replacing equipment or machinery may be expensive, but remember the average direct and indirect cost of a lost work time injury is over $39,000 and more than a million dollars to close a fatality claim.

Some examples of these two strategies include:

  • Removing 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 eliminating or reducing the actual source of the hazard, unlike other control strategies that generally focus on employee exposure to the hazard. The basic concept behind engineering controls is that, to the extent feasible, the work environment and the job itself should be designed to eliminate hazards or reduce exposure to hazards. While this approach is called engineering controls, it does not necessarily mean that an engineer is required to design the control.

Why Engineering Controls?

Although hazardous conditions directly account for only about 3% of all workplace injuries, top priority should be given to eliminating them. If elimination or substitution is not possible, OSHA law requires employers to attempt to remove hazards through the use of feasible engineering controls because they also have the potential to totally eliminate hazards in the lab.

Engineering controls do not necessarily have to be expensive or complicated. They can be quite simple in some cases. Engineering controls are based on the following broad strategies:

  1. If feasible, design or redesign the tools, equipment, machinery, materials and/or facility.
  2. Enclose the hazard to prevent exposure in normal operations; and
  3. If complete enclosure is not feasible, establish barriers or local ventilation to reduce exposure to the hazard in normal operations.

Enclosure of Hazards


When you cannot remove a hazard and cannot replace it with a less hazardous alternative, the next best control in the laboratory 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; and
  • Complete containment of noise, heat, or pressure producing processes with materials especially designed for those purposes.

Barriers or Local Ventilation


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

If elimination, substitution or engineering controls eliminate the hazard, it may also remove the need to control employee behaviors through the use of administrative controls. Remember:

No hazard... no exposure... no accident.

Administrative Controls

Safe Chemical Handling

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 most workplace accidents. Examples include:

  • Developing a Chemical Hygiene Plan, and
  • Developing Standard Operating Procedures for chemical handling.

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. Here’s an important principle that reflects this idea.

Any system that relies on human behavior is inherently unreliable.

To make sure management controls are effective in the long term, they must be designed from a base of solid hazard analysis and sustained by a supportive safety culture. They then must be accompanied by adequate resources, training, supervision, and appropriate consequences. Remember, administrative controls should be used in conjunction with, and not as a substitute for, more effective or reliable engineering controls. Now, let's look at examples of some administrative controls.

Personal Protective Equipment (PPE)

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Using personal protective equipment is a very important safe work practice. It's important to remember, 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 are being installed or work practices developed.

PPE Drawbacks

The limitations and drawbacks of safe work practices also apply to PPE. Employees need training in why the PPE is necessary and how to use and maintain it. It also is important to understand that PPE is designed for specific functions and are not suitable in all situations. For example, no one type of glove or apron will protect against all solvents. To pick the appropriate glove or apron, you should refer to recommendations on the safety data sheets of the chemicals you are using.

Your employees need positive reinforcement and fair, consistent enforcement of the rules governing PPE use. Some employees may resist wearing PPE according to the rules, because some PPE is uncomfortable and puts additional stress on employees, making it unpleasant or difficult for them to work safely. This is a significant drawback, particularly where heat stress is already a factor in the work environment. An ill-fitting or improperly selected respirator is particularly hazardous, since respirators are used only where other feasible controls have failed to eliminate a hazard.

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 reduce or remove a hazard.


Maintenance Strategies to Control Hazards

What two general types of maintenance processes are needed?

  • Preventive maintenance to make sure equipment and machinery operates safely and smoothly
  • Corrective maintenance to make sure equipment and machinery gets back into safe operation quickly

Hazard Tracking Procedures

An essential part of any day-to-day safety and health effort is the correction of hazards that occur in spite of your overall prevention and control program. Documenting these corrections is equally important, particularly for larger sites.

Documentation is important because:

  • It keeps management and safety staff aware of the status of long-term correction items.
  • It provides a record of what occurred, should the hazard reappear at a later date.
  • It provides timely and accurate information that can be supplied to an employee who reported the hazard.

Final Thoughts

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 life... you are saving a father, a mother, a son, or a daughter... you are saving a family. It's worth the effort.


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. To combat these hazardous conditions and unsafe work practices in the laboratory, control strategies, called the _____ have been developed?

2. Elimination, as a hazard control strategy is considered the top priority because it has the potential to do which of the following?

3. Which of the following hazard control strategies is aimed at reducing employee exposure to hazards that other controls fail to eliminate?

4. There is usually no hazard exposure to workers during normal operations by _____.

5. To pick the appropriate glove or apron, you should refer to recommendations on the _____ of the chemicals you are using.

Have a great day!

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