Ask the Experts: Evaluating Ergonomics Hazards
By Walt Rostykus, CPE, CSP, CIH

Question:

Our manufacturing facility has some workstations that we are planning on evaluating for ergonomic hazards, such as too far of a reach for work tasks and repetitive motions. What are the initial hazard assessment questions we should ask as we evaluate each work area?
R.L., Des Moines , Iowa

Response:

For any workplace or job task, an assessment of ergonomic hazards should look for and measure the three primary risk factors known to contribute to work-related musculoskeletal disorders (WMSDs):

• Awkward posture
• High force
• Time (either high frequency or long duration)

The presence of one, two, or all three risk factors indicates increasing exposure to the causes of WMSDs at a given part of the body.

A hazard assessment for ergonomic risk factors is best accomplished by questioning, observing and measuring. Instead of relying on a written job description, ask employees about challenges they encounter in performing their task and for ideas on changes to improve it. Employees know best the challenges involved and can provide valuable information needed to identify solutions. Remember, however, that their input may be subjective.

Simple observation-based checklists can help you look for and record instances of awkward postures and/or high forces held for a long duration or performed with great frequency. The presence of such risk factors is a good indicator that there may be an ergonomic issue in your workplace. You can use the results of this initial assessment to determine where potential risks exist and where to focus more in-depth assessments.

To objectively assess ergonomic risk factors, use a valid, quantifiable method. A measurable assessment method enables you to determine and compare the postures, forces, frequency and duration of a required task with known limits of human performance. Just as occupational noise exposure is compared with existing thresholds, valid ergonomic assessment methods allow comparison with known thresholds for ergonomic risk factors. One challenge with determining a threshold for ergonomic risk is the differences in the muscle and joint structures at each major joint in the body. For example, the thresholds for awkward posture, high force, and frequency/duration vary for the wrist, elbow, shoulder, and neck.

The key is to use a valid and repeatable ergonomic assessment method that is based on current research. Several proven assessment methods are available both commercially and through the public sector, including the National Institute for Occupational Safety and Health's (NIOSH) lifting equation and the rapid entire body assessment (REBA). (See sidebar below.) Some assessment methods are specific to a part of the body, while some are used for whole-body assessment. Know the capabilities and limitations of the method you choose.

WP

Walt Rostykus, CPE, CSP, CIH, is an ergonomics engineer and vice president for Humantech.

Calculating the Lifting Equation

The "Applications Manual for the Revised NIOSH Lifting Equation" [DHHS (NIOSH) Publication No. 94-110] includes methods and examples for accurately applying the lifting equation to a variety of lifting tasks.

To view the document, visit http://www.cdc.gov/niosh/docs/94-110.

Types of Controls for Reducing Ergonomic Injuries

• Engineering controls reduce or eliminate potentially hazardous conditions. Examples of engineering controls to reduce ergonomic injuries include changing methods for transporting products, changing the process or product, modifying containers, and changing workstation layout.
• Administrative controls are changes in work practices or management policies. These can include additional rest periods, rotating workers through jobs that are physically challenging, and worker training to recognize ergonomic risk factors.
• The use of personal protective equipment (PPE) to reduce ergonomic injuries has been studied for some years, but its effectiveness remains inconclusive. The expectation of PPE is that it will place a barrier between the worker and the hazard, such as respirators, hearing protection or eye protection. Although ergonomic equipment, such as braces, wrist splints or back belts, may reduce some exposure to ergonomic hazards, use of the equipment may require a worker to overcompensate in another area to work around the equipment.

WP

Source: National Institute for Occupational Safety and Health Institute, Safety and Health Topic: Ergonomics and Musculoskeletal Disorders
http://www.cdc.gov/niosh/