Iranian Journal of Ergonomics

Musculoskeletal disorders (MSDs) are the second most common occupational diseases followed by occupational respiratory diseases [1]. The main disadvantages of these disorders include: absenteeism, loss of time, increased costs and labor shortages, which in turn lead to reduced productivity [2]. Physical and mechanical risk factors for abnormalities include inappropriate posture, contact pressure, excessive force, full-body or local vibration, repetitive work, low work temperature, lifting and handling, and inadequate lighting [3].
Posture assessment methods in the field of ergonomics have made it possible to evaluate worker exposure to a range of musculoskeletal disorders risk factors [13]. There are several ways to reduce the damage caused by musculoskeletal disorders, such as the Quick Exposure Check (QEC) and WERA (Workplace Ergonomic Risk Assessment) [14, 13].
One of the most important steps in achieving workforce health is to apply the right principles of ergonomics, which can then be followed by human adaptation to the workplace and a reduction in musculoskeletal disorders. In the industry studied in this study, which is a modern brick industry, there is a risk of developing musculoskeletal disorders due to the risk factors such as repetitive work, inappropriate posture, shifting, etc. The purpose of this study was to evaluate the possibility of using WERA method to assess the risk of musculoskeletal disorders by correlating its results with the results of QEC method, which is a common method with appropriate validity and reliability.

 

In this descriptive cross-sectional study, 72 employees of workshop units of a modern brick industry in different occupations were enrolled. These jobs included brick layering, wagon unloading, metal casing and pallet making (Figure 1). The tools used in this study for data gathering were Nordic questionnaire for assessment of musculoskeletal disorders in the last 12 months, as well as two methods of "rapid exposure assessment (QEC)" and "workplace ergonomic risk assessment (WERA)". In this study, after obtaining informed consent from the subjects under study, the necessary training on the implementation of the plan and the benefits of the project were explained to the subjects.
Data were analyzed by SPSS 18 software (SPSS Inc., Chicago, Ill., USA) and analyzed by t-test, analysis of variance and correlation as well as significance level less than 0.05.

Figure 1. An overview of the different tasks in a modern brick industry. (a): Metal case (b): Pallet making (c): Wagon unload (d): Brick layering

The prevalence of back, shoulder, neck and wrist disorders were 41.7%, 20.8%, 16.7% and 33.3%, respectively (Table 1). Results of WERA showed that 88.9% of subjects had medium action level and 11.1% had high action level (Table 2). In QEC method, 6.9% of subjects had exposure level ‘one’, 20.8% of subjects had exposure level ‘two’, 48.6% of subjects had exposure level ‘three’, and 23.7% of subjects had exposure level ‘four’ (Table 3). The correlation between QEC total score and prevalence of musculoskeletal disorders was (r=0.67, P=0.038)9. The correlation coefficient between the final scores of the two methods was (r=0.53, P=0.021) (Table 4).
 

Table 1. Frequency and prevalence of MSDs from Nordic questionnaires in different parts of the body and their relationship with age

* There was a statistically significant difference (P<0.05). ** Analysis of variance


Table 2. Average WERA final score and priority level of corrective action in different tasks

Table 3. Survey results of exposure level to (MSDs) in quadrants based on QEC method score

Table 4. Investigation of Correlation between Results of QEC and WERA Methods in Different Tasks

Investigation of the correlation between the mean scores obtained from the two methods used in this study for all workers showed a significant but moderate correlation between the scores obtained from the two methods. Correlation between prevalence of musculoskeletal disorders obtained from Nordic questionnaire and final scores of QEC and WERA methods also showed that results of QEC method are closer and more consistent with results of Nordic questionnaire.

 

The results of this study showed that the results of QEC method compared to WERA method were more consistent with the results of the study of musculoskeletal disorders by Nordic questionnaire and also the QEC method was more sensitive than WERA method in determining the corrective action priorities. The practical significance of these findings is that using the QEC method is more appropriate than the WERA method for ergonomic risk factors of musculoskeletal disorders for the tasks studied in this study and many other tasks with similar risk factors.

 

The authors of this article wish to thank the management, the employees of the Safety and Health Unit and the honorable staff of Iran Refractory Products Company, who, despite all the difficulties, had a good and sincere cooperation in the implementation of this research. The research is funded by the authors.

 

The authors declared no conflict of interest regarding the publication of this article.