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Controlling Risk Factors

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Rid the Job of Risk Factors

Analyzing jobs to identify factors associated with risks for MSDs lays the groundwork for developing ways to reduce or eliminate ergonomic risk factors for MSDs.

The Hierarchy of Hazard Control Strategies

Controlling hazards and exposures to occupational hazards is the fundamental method of protecting workers. ANSI/ASSP Z10-2012, Occupational Health and Safety Management Systems, encourages employers to use the following hierarchy of hazard controls:

  1. Elimination
  2. Substitution
  3. Engineering controls
  4. Warnings
  5. Administrative controls
  6. 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.

1. Which of the following hazard control strategies is potentially most effective?

a. Administrative controls
b. Engineering controls
c. Elimination
d. Substitution

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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 an ergonomics hazard. Some obvious examples of elimination include eliminating the need to carry heavy containers by replacing them with smaller containers. You can substitute that old office chair with a new ergonomically designed chair.

These strategies are considered first because they have the potential of completely eliminate the hazard, thus greatly reducing the probability of an accident. Redesigning or replacing equipment or machinery may be expensive, but remember that, according to the National Safety Council, the average direct and indirect cost of a lost work time injury more than $38,000 and most injuries in the workplace are ergonomics-related.

Check out this short audio clip by Dan Clark of the Good workstation planning with effective ergonomics will also help guarantee worker safety.

2. Elimination and substitution are most effective at reducing hazards but _____.

a. are usually less effective in controlling behaviors
b. take longer to implement as an ergonomic solution
c. may be the most difficult to implement in existing processes
d. hard to implement as part of new processes

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Engineering Controls

The preferred approach to prevent and control MSDs is to design the job including:

  • the workstation layout
  • selection and use of tools
  • work methods to take account of the capabilities and limitations of the work force

A good match, meaning that the job demands pose no undue stress and strain to the person doing the job, helps ensure a safe work situation.

Engineering controls are preferred because they may completely eliminate the hazard. No hazard: No injury! They also do not rely on human behavior nor do they require continual oversight to work. Finally, engineering controls may save the company far more than the initial investment. Engineering control strategies to reduce ergonomic risk factors include the following:

  • Changing the way materials, parts, and products can be transported. For example, using mechanical assist devices to relieve heavy load lifting and carrying tasks or using handles or slotted hand holes in packages requiring manual handling.
  • Changing the process or product to reduce worker exposures to risk factors. Examples include maintaining the fit of plastic molds to reduce the need for manual removal of flashing or using easy-connect electrical terminals to reduce manual forces Modifying containers and parts presentation, such as height-adjustable material bins.
  • Changing workstation layout. Examples might include using height-adjustable workbenches or locating tools and materials within short reaching distances.
  • Changing the way parts, tools, machinery and materials are to be manipulated. Examples include using fixtures (clamps, vise-grips, etc.) to hold work pieces to relieve the need for awkward hand and arm positions or suspending tools to reduce weight and allow easier access.
  • Changing tool designs. For example, pistol handle grips for knives to reduce wrist bending postures required by straight-handle knives or squeeze-grip-actuated screwdrivers to replace finger-trigger-actuated screwdrivers.
  • Changes in materials and fasteners. For example, lighter-weight packaging materials to reduce lifting loads.
  • Changing assembly access and sequence. For example, removing physical and visual obstructions when assembling components to reduce awkward postures or static exertions.

3. Each of the following is an advantage of using engineering controls EXCEPT _____.

a. they require continual oversight and management
b. they do not depend on correct human behavior to work
c. they can save the company far more than their initial cost
d. they can eliminate the hazard

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Work Practice and Administrative Controls

Work practice and administrative controls are closely related attempts to change behaviors. They are management-dictated work practices and policies to reduce or prevent exposures to ergonomic risk factors. Work practice and administrative control strategies include:

  • Changes in job rules and procedures such as scheduling more rest breaks
  • Rotating workers through jobs that are physically tiring
  • Training workers to recognize ergonomic risk factors and to learn techniques for reducing the stress and strain while performing their work tasks

Although engineering controls are preferred, work practice and administrative controls can be helpful when engineering controls are not technically feasible. However, since work practice and administrative controls focus on eliminating or reducing exposure (not the hazard itself), they require diligent management, training, supervision, and enforcement to be effective. They work only as long as people behave!

Common examples of administrative control strategies for reducing the risk of MSDs are as follows:
  • Reducing shift length or curtailing the amount of overtime
  • Rotating workers through several jobs with different physical demands to reduce the stress on limbs and body regions
  • Scheduling more breaks to allow for rest and recovery
  • Broadening or varying the job content to offset certain risk factors (e.g., repetitive motions, static and awkward postures)
  • Adjusting the work pace to relieve repetitive motion risks and give the worker more control of the work process
  • Training in the recognition of risk factors for MSDs and instruction in work practices that can ease the task demands or burden

Check out this short audio clip by Dan Clark of the Stretch breaks for employees have big benefits. You lose a little production time, but make bigger gains in productivity. In this podcast, Dan mentions many computer and mobile apps to schedule and time a stretch break.

4. What is a major weakness of using administrative controls to mitigate ergonomic hazards?

a. They work only as long as workers comply with them
b. They are generally more expensive to implement
c. There are fewer options available for use by workers
d. They require more technical expertise than engineering controls

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Personal Protective Equipment

Back belts help to remind us to use proper lifting techniques, but as you can see here, it doesn't always work.

One of the most controversial questions in the preventing MSDs is whether using PPE (such as wrist supports, back belts, or vibration attenuation gloves) is effective.

Ergonomics PPE devices may, in some situations, reduce the duration, frequency, or intensity of exposure, but evidence of their effectiveness in injury reduction is inconclusive. In some instances they may decrease one exposure but increase another because the worker has to "fight" the device to perform his or her work. An example is the use of wrist splints while engaged in work that requires wrist bending.

Back belts are sometimes provided as PPE, but they are controversial. Back belts have been studied extensively, and experts have concluded that they are not effective in preventing back injuries. Some believe that, in fact, they may cause injury by encouraging workers to lift heavier objects or by making muscles weaker. Most importantly, they do not make workers stronger or more able to perform a lift that is awkward or too heavy.

The National Institute for Occupational Safety and Health (NIOSH) recommends that employers not rely on back belts to protect workers. Instead, it recommends that employers implement a comprehensive ergonomics program that includes workplace assessment, hazard reduction, and worker training.

Less controversial types of personal equipment include:

  • clothing that accommodates extreme temperatures
  • grinder
    This worker would benefit from using vibration attenuation gloves.
    • hand, wrist, elbow, knee, and ankle supports
    • vibration attenuation gloves, and
    • knee pads for carpet layers

    Remember, ergonomics control strategies may not be immediately obvious. If you can't figure out an effective solution, don't forget to take advantage of an outside expert. Participating in the consultation process with an ergonomist is a real win-win for your company and an excellent education for you.

    5. The most controversial ergonomics practice is the use of _____ as personal protective equipment.

    a. wrist supports
    b. clothing
    c. knee pads
    d. back belts

    Check your Work

    Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.



    In this video Dr. Ergo talks about using the knee or the hand to make repeated impacts.

    Here's another video that explains the arm-level equation to help train employees how to lift properly.


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