Workplace Ergonomics Risk Assessment (WERA) and Standard Nordic Questionnaire (SNQ) Methods for Analysis of Work Posture Improvements in Ergonomics

Written by : Asael Juventino Karsten (WDE Assistant 2018)

Background

In the current era of industrial development, there is still quite a lot of work that is done manually and semi-automatically by a worker in the office, home, factory, or field project. Any work that is done manually or semi-automatically has the potential to cause fatigue and mild to severe injury. These situations can happen because the posture of workers in carrying out their duties and work does not reflect ergonomic principles.

Ergonomics itself according to Tarwaka and Sudiajeng (2004), comes from the Greek, namely “Ergon” which means work, and “Nomos” which means natural laws. Therefore, ergonomics can be defined as a study related to human aspects with their work environment which is reviewed in terms of anatomy, physiology, psychology, engineering, management and design. Meanwhile, according to Nurmianto (2004), work posture is an action taken by workers in doing their work. In its application, work posture is closely related to ergonomics science to reduce or eliminate the potential for Work-Related Musculoskeletal Disorders (WMSDs) and mental disorders.

According to Anizar & Suriadi (2008), Musculoskeletal Disorders (MSDs) themselves are complaints that are felt by a person on a very mild to very painful scale in parts of the skeletal muscles caused by the wrong attitude or position. Work postures that are classified as less ergonomic need to be improved by using an analytical approach to improving work postures in ergonomics. There are several analytical methods for improving work posture in ergonomics, including the Workplace Ergonomics Risk Assessment (WERA) and Standard Nordic Questionnaire (SNQ) methods.

Purpose

In the application of ergonomics, several methods can be used to measure and analyze workloads. Each of these methods has its advantages, disadvantages, and limitations. Therefore, the use of each selected method can be adjusted in advance to the case studies and existing research limitations. Some examples of methods that can be used are the Workplace Ergonomics Risk Assessment (WERA) and Standard Nordic Questionnaire (SNQ) methods.

According to Rahman (2011), the Workplace Ergonomics Risk Assessment (WERA) method is a tool used to quickly screen tasks to describe the physical risk factors associated with WMSDs. The WERA assessment consists of six physical risk factors including posture, repetition, strength, vibration, contact stress, and duration of work involving five main body parts, namely shoulders, wrists, back, neck, and feet. This method can be used in more detail to measure the potential for WMSDs that can be suffered by workers but requires computer aids to determine angles and other measurement tools to further analyze the existing factors.

Meanwhile, the Standard Nordic Questionnaire (SNQ) method is a form of checklist questionnaire in the science of ergonomics and is often used to determine the discomfort of workers. This method is also standardized and neatly arranged. This method is used to know and analyze in more detail the 27 body parts of workers that feel pain and cause the greatest potential for WMSDs compared to other body parts so that the recommendations for improvement can be more focused on that part of the worker’s body. This method does not require the use of measuring tools or computer aids to analyze, but only needs to be interviewed with related workers.

Application of Workplace Ergonomics Risk Assessment (WERA) Method

According to Rahman (2011), The Workplace Ergonomics Risk Assessment (WERA) method is a method used to measure the development of an ergonomic risk assessment in the workplace to detect physical risk factors associated with Work-related Musculoskeletal Disorders (WMSDs) in the work being reviewed. This method has an assessment system and a level of action that guides the level of risk and the need to conduct an assessment with more detailed provisions.

In the application of using the WERA method to detect physical risk factors associated with Work-related Musculoskeletal Disorders (WMSDs), there are five steps of the procedure :

1.Observing Tasks/Jobs

In this first step, observations are made on the tasks/jobs to be able to formulate an assessment of the ergonomics of the workplace, in general including the impact factors of the layout and work environment, use of equipment, and worker behavior related to risk-taking. If possible, the captured data is also stored in the form of photos or videos.

2. Selecting Tasks/Jobs for Assessment

In this second step, the tasks/jobs to be analyzed are determined based on the results of the first step. The following are criteria that can be used.

1. Tasks/jobs that are done repeatedly.
2. Extreme, unstable, or awkward posture.
3. Tasks/jobs that cause inconvenience to workers.
4. Requires great force, physical contact stress, and the use of tools that generate vibrations.

3. Determining the Score of the Tasks / Jobs

In this third step using the WERA method, the scores assigned to each risk factor item including part A and part B (items number 1-9) are determined as follows.

1. Part A (items number 1-5) : This section consists of five main body areas, including the shoulders; wrist; back; neck; and feet. This section covers two physical risk factors for each body part including posture and repetitive activities.
2. Part B (items number 6-9) : This section consists of four physical risk factors including strength, vibration, contact stress, and duration of the task/job.

4. Perform Exposure Score Calculations.

In this fourth step, the score is calculated for each item in both parts A and B, as well as the total final score. Then mark the number at the point where each circled pair crosses (column vs row). Here are the calculation details.

1. In part A, for items numbered 1-5, calculations are made based on pairs of posture measurements and also repeated activities. For example, in item 1, shoulder posture (1a) is compared with repetitive shoulder activity (1b).
2. In part B, for items 6-8, the side row is calculated the same as the posture following part A. For example, in item 6 – the strength section(6) is compared to the shoulder posture (3a). Then for item number 9, adjusted based on the strength row side (6).

After the score for each risk factor item numbered 1-9, then the total final score was calculated.

5. Action level considerations.

In this fifth step, the final total score will have an action level classification as follows.

1. Total final score 18-27  : the task/job is acceptable with a low level of risk
2. Total final score 28-44 : the assignment/job is still acceptable but needs further review and minor changes are needed and the risk level is moderate.
3. Final total score 45-54 : the task/job is unacceptable and needs to be made major changes immediately with a high level of risk.

The following is a worksheet for the Workplace Ergonomic Risk Assessment (WERA) method shown in Figure 1.

Figure 1. Workplace Ergonomics Risk Assessment (WERA) method worksheet 

Source: http://ergo.human.cornell.edu/ahWERA.html

Application of the Standard Nordic Questionnaire (SNQ) Method

Standard Nordic Questionnaire (SNQ) is an indirect ergonomic measurement method in the form of a questionnaire that is used to determine discomfort or complaints of pain in the body and can identify Work-related Musculoskeletal Disorders (WMSDs) from workers. SNQ can also identify the muscle parts that experience complaints with 4 levels of complaints, namely starting from No Pain (TS), Slightly Pain (AS), Pain (S), and Very Pain (SS). With this analysis based on a map of the human body, it is possible to estimate the type and level of skeletal muscle complaints felt by workers. The following is an example of a questionnaire for data collection.

Figure 2. Worksheet Nordic Body Map / Standard Nordic Questionnaire (SNQ)

In the Standard Nordic Questionnaire (SNQ) questionnaire method, direct data collection will be carried out through interviews or filling out questionnaires from workers who want to be studied. From the results of the questionnaire obtained, then a score will be given to workers related to the Likert scale that has been set to find out which part of the human body has the greatest potential for WMSDs for the worker. The scale used is following the information contained in the questionnaire itself, namely:

1. No Pain : score 1 – workers do not feel interference in certain parts,
2. Slightly Pain : score 2 – the worker feels a little disturbance or pain in the     

  certain parts, 

1. Pain : score 3 – feeling discomfort in certain body parts, 
2. Very Sick : score 4 – feel discomfort in a certain part of the large scale.

Based on the results of scoring according to a predetermined scale, then the scores for each type of complaint will be added up to identify the overall corrective action that needs to be taken for the workers concerned. The following is a classification of risk levels based on the total score of workers with a description of the level of improvement that needs to be applied.

Table 1. Classification of Risk Levels Based on Total Worker Score and Level of Improvement

Closing

Work that is done manually or semi-automatically in an office, factory, home, or fieldwork environment has the potential to cause Work-Related Musculoskeletal Disorders (WMSDs). Therefore, it is necessary to identify and analyze the workload of workers to reduce the risk of WMSDs and improve the quality of their work. In the identification and analysis of this workload, the Workplace Ergonomics Risk Assessment (WERA) method can be used to quickly and precisely analyze what activities have the greatest potential for WMSDs. Then based on the results of the analysis, a posture analysis can be carried out using the Standard Nordic Questionnaire (SNQ) method to be able to determine recommendations for improvement that can focus on what body part of the worker.

References

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Anizar & Joko Suriadi. (2008). Analisa Postur Kerja Operator Pada Bagian Boiler Dengan Metode Ovako Working Posture Analysis System Di PTPN V Sei Rokan Riau. Makalah dalam Seminar Nasional Teknik Industri dan Kongres BKSTI V. Makassar,16-17 Juli 2008.

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Rahman, M.N.A., Jaffar, M.S.M, Hassan, M.F., Ngali,, M.Z., Pauline, O. (2017). Exposure Level of Ergonomic Risk Factors in Hotel Industries. International Research and Innovation Summit. Malaysia.

Rahman, M.N.A., Rani, M.R.A., Rohani, J.M. (2011). WERA: An Observational tool Develop to Investigate the Physical Risk Factor Associated with WMSDs. NCBI. [Online]. Retrieved arch 8 March, 2018, from https://ncbi.nlm.nih.gov/pubmed/25665205.

Bridger, R.S. (2003). Introduction to Ergonomics 2nd edition. Taylor & Francis, Inc. London. 

Kroemer, K. H. E, H. B. Kroemer, dan K. E. Kroemer-Elbert. (2001). Ergonomics: How to Design for Ease and Efficiency. Prentice Hall: New Jersey.

Nurmianto. (1996). Ergonomi, Konsep Dasar dan Aplikasinya. PT. Guna Widya. Jakarta.

Tarwaka, Solichul HA. Bakri, Lilik Sudiajeng. (2004). Ergonomi untuk Keselamatan Kerja dan Produktivitas. Surakarta, Penerbit: UNIBA Press.

Tarwaka. (2011). Ergonomi Industri, Dasar-Dasar Pengetahuan Ergonomi dan Aplikasi di Tempat Kerja. Penerbit: Harapan Press Solo

Wignjosoebroto, Sritomo (2003), Ergonomi, Studi Gerak dan Waktu, edisi pertama, Penerbit Guna Widya, Surabaya.