Worksite Analysis | Ergonomics

A worksite analysis provides for both the identification of problem jobs and risk factors associated with these jobs. The worksite analysis can be used to determine what jobs and workstations are the source of the greatest problems. Recognizing the signs that may indicate a problem through a systematic analysis of injury and illness records can be done to accomplish this step.

Analyze Company Data

First, analyze all existing medical, safety, and insurance records, including the OSHA 200 log and workers' compensation claims for evidence of ergonomic illnesses such as carpal tunnel syndrome, tendonitis, tenosynovitis, and low back pain. When you analyze the OSHA 200 log, look for these clues relating to cumulative trauma disorders associated with ergonomically hazardous jobs.

• When the illness began (was there a lot of overtime, a speed-up in production, or introduction of new equipment around this time).

• What is the employee's job title and department (a clue to the type of tasks being performed).

• Column F: Description of injury or illness. Terminology given may be confusing. Some key terms for cumulative trauma disorders include arthritis, carpal tunnel, numbness, pain, strain, and tendonitis. Check your first report of injury forms for more details on questionable cases.

• Column 7f: Disorders associated with repeated trauma. Check thoroughly. Not all repeated trauma cases are posted in this column. The descriptions in Column F are more inclusive, so always check both columns.

• Back disorders are not listed in Column 7f. Even though they are usually due to repeated trauma, they are classified as injuries on the 200 form and must be listed in Column F. You need to check there for back-related CTDs.

This process may need to involve health care providers to ensure confidentiality of patient records.

Identify and Analyze Trends

Second, identify and analyze any apparent trends or ergonomic problems relating to particular departments, process units, production lines, job titles, operations, or workstations.

• Certain jobs or work conditions cause worker complaints of undue strain, localized fatigue, discomfort, or pain that does not go away after overnight rest.

• Workers visiting the clinic make frequent references to physical aches and pains related to certain types of work assignments.

• Job tasks involve activities such as repetitive overhead lifts; awkward work positions; or use of vibrating equipment.

A company's initial efforts in ergonomics should be directed toward fixing the most obvious problem jobs. Implementing the program can have value by enabling early detection of and more timely interventions in potential ergonomic problems. Also, an ergonomics program can influence the design of future changes in work processes to reduce the possibility of musculoskeletal disorders.

This information will provide you with an idea about where "problem jobs" exist. Worker surveys and a background knowledge of certain jobs considered "high risk" can also help in targeting specific worksite analyses. Employee questionnaires on ergonomic problems and issues are a useful way to gather information about work conditions that may contribute to ergonomic hazards. Other forms of regular employee participation might include a complaint log or a suggestion book.

Determine Risk Factors

The next step to take is conducting a more detailed analysis of those job tasks and positions determined to be problem areas for their own specific ergonomic risk factors. This analysis can be done with a checklist and should be performed either by direct observation or, where feasible, through videotape review. The analysis should be routinely performed and documented by a qualified person, ideally an ergonomist, although trained engineers, managers, health care providers, and affected employees can often contribute significantly to the process.

A combination of risk factors rather than any single factor may be responsible for the occurrence of musculoskeletal disorders. Therefore, identifying all the risk factors that may be present in the job is important. Some typical risk factors for cumulative trauma and back disorders that are likely to be identified in a worksite analysis include:

• Excessive repetition or prolonged activities such as for an 8-hour shift, cause fatigue and muscle/tendon strain which can accumulate and may result in permanent tissue damage.

• Forceful exertions (including lifting, pushing, and pulling) place higher loads on the muscles, tendons, and joints. As the force increases, the muscles fatigue more quickly.

• Pinch grips which usually place three to four times more force on the tendons than power grips.

Postures determine which muscles are used in an activity and how forces are translated from the muscles to the object being handled. More muscular force is required when awkward postures are used because muscles cannot perform efficiently.

Look for these postures when analyzing a task:

• Prolonged static postures of the body, trunk or its extremities, either sitting or standing.

• Awkward postures of the upper body, including reaching above the shoulders or behind the back.

• Excessive bending or twisting of the hand or wrist.

• Continued elevation of the elbow and forearm.

• Continued physical contact with work surfaces, such as contact with edges of machines can inhibit nerve function and blood flow.

• Inappropriate or inadequate hand tools that cause awkward posturing.

• Restrictive workstations and inadequate clearances that may cause stooping and bending.

• Improper seating or support.

• Bad body mechanics such as continued bending at the waist, continued lifting below the knuckles or above the shoulders, or twisting at the waist while lifting.

• Lifting heavy objects or objects of abnormal sizes without mechanical aids.

• Lack of adjustable chairs, footrests, body supports, and work surfaces at workstations or slippery footing.

Perform the Job Analysis

Job analysis breaks a job into its various elements or actions, describes them, measures and quantifies risk factors inherent in the elements, and identifies conditions contributing to the risk factors. Most job analyses have several common steps. Each task is studied to determine the specific risk factors that occur during the task. Sometimes each risk factor is evaluated in terms of its magnitude, that is, the number of times it occurs during the task, and how long the risk factor lasts each time it occurs.

The tasks of most jobs can be described in terms of (1) the tools, equipment, and materials used to perform the job, (2) the workstation layout and physical environment, and (3) the task demands and organizational climate in which the work is performed. Job screening provides some of this data. More definitive procedures for collecting information on these components can include the following:

• Observing the workers performing the task in order to furnish time-activity analysis and job or task cycle data; videotaping the workers is typically done for this purpose.

• Still photos of work postures, workstation layouts, tools, etc., to illustrate the job.

• Workstation measurements (e.g., work surface heights, reach distances).

• Measuring tool handle sizes, weighing tools and parts, and measuring tool vibration and part dimensions.

• Determining characteristics of work surfaces such as slip resistance, hardness, and surface edges.

• Measuring exposures to heat, cold, and whole body vibration.

• Biomechanical calculations (e.g., muscle force required to accomplish a task or the pressure put on a spinal disc based on the weight of a load lifted, pulled or pushed).

• Physiological measures (e.g., oxygen consumption, heart rate).

• Special questionnaires, interviews, and subjective rating procedures to determine the amount of perceived exertion and the psychological factors influencing work performance.

Jobs in which current cases have been identified should receive immediate attention, followed by those in which past records have noted a high incidence or severity of musculoskeletal disorders despite the lack of current cases. Priority for job analysis and intervention should be given to those jobs in which most people are affected or in which work method changes are going to be taking place anyway.

The analysis should take multiple causes into consideration, as the combined effect of several risk factors often results in the onset of cumulative trauma disorders. Jobs, operations, or workstations that have multiple risk factors have a higher probability of causing these disorders.

Ideally, all risk factors within a problem area should be identified and proper controls implemented to eliminate each of them. The goal of an ergonomic approach is to make things better than they were before. Incremental improvements in reducing or eliminating some, if not all, risk factors within a problem area will reduce the cumulative risk and the overall level of physical stress for the worker. Thus, the benefits of hazard prevention and control strategies can be quite significant.