# Towards an Ergonomic Assessment Framework for Industrial Assembly Workstations--A Case Study
## 3 Results and Discussion  
### Characterization of the Initial Problem--Assembly Workers and Workstations  
The workforce of the assembly section is composed of 60 female workers divided across 3 work shifts. However, in the current study, a sample of 44 workers was constituted (who volunteered to participate). They are women with an age of 41.4 (\(\pm\) 10.3) years old, with a length of employment of 9.6 (\(\pm\) 2.2) years and all of them are right-handed. Of those, 17 workers had one or more medically diagnosed musculoskeletal problems. The musculoskeletal disorders identified and the number of workers affected are the following: (i) tendinitis at the upper limbs (\(n\) = 9); (ii) disc herniation (\(n\) = 7); (iii) carpal tunnel syndrome (\(n\) = 4); (iv) rheumatoid arthritis (\(n\) = 1); (v) arthrosis at the back (\(n\) =1). Relatively to the NMQ results (Figure 2), the McNemar test proved the existence of a perfect concordance (\(p\) = 1.000) between the workers' perceptions for the last 12 months and the last 7 days across the body regions considered. Therefore, the NMQ results presented in Figure 2 are related to the prevalence of musculoskeletal discomfort/pain along the last 12 months. The results demonstrate that all of the inquired workers reported any musculoskeletal symptoms, even the workers without previously disorders diagnosed. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Global Risk Level**} & \multicolumn{2}{c}{**RULA**} & \multicolumn{2}{c}{**KIM-MHO**} \\ \cline{2-5}  & **Final Score** & **Meaning** & **Final Score** & **Meaning** \\ \hline \multirow{4}{*}{**I**} & \multirow{4}{*}{1 or 2} & It indicates that posture is & \multirow{4}{*}{\(<\)10} & Low load situation, \\  & & acceptable if it is not & & health risk from physical \\  & & maintained or repeated for & & overload is unlikely to \\  & & long periods. & & appear. \\  & & & & Moderate load situation, \\  & & It indicates that further & & physical overload is possible \\
**II** & 3 or 4 & investigation is needed and & 10 to \(<\)25 & for less resilient persons. For \\  & & changes may be required. & & this group redesign of the \\  & & & & workplace is helpful. \\  & & & & Increased load situation, \\  & & It indicates that & & physical overload also \\
**III** & 5 or 6 & investigation and changes & 25 to \(<\)50 & resilient persons. \\  & & are required soon. & & The redesign of the \\  & & & & workplace should be \\  & & & & reviewed. \\  & & It indicates that & & High load situation, physical \\
**IV** & 7 & investigation and changes & \(\geq\)50 & overload is likely to appear. \\  & & are required immediately. & & Workplace redesign is \\  & & & & necessary. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Global risk levels’ definition based on the outputs of the methods considered. The results obtained by the FIOH method are presented in Table 5, indicating that the workstation presents several constraints for the workers' postures (topic 4), such as arms elevation above the shoulders' height. The work restrictiveness (topic 7) and repetitiveness (topic 10) are two of the parameters with a higher risk (4 points in the FIOH scale) due to the limited work content and short cycle durations (less than 5 min). The assembly workers (\(n=44\)) reported their perceptions through the FIOH method (Figure 3). The Friedman test proves that the answers' distribution is different across the 14 questions, with a test value Q (13) = 320,433. Therefore, the Friedman pairwise comparison reveals that 3 groups of the FIOH topics obtain an equivalent answer distribution. This statistical analysis demonstrates the division of the FIOH topics across the following groups: (i) more positive topics (7; 8; 9; 11; 12); (ii) intermediate (1; 3; 5; 14); and (iii) more negative topics (2; 4; 10; 13). One can also conclude from the analysis that the occupational conditions that require urgent intervention are: physical activity, postures and movements, work repetitiveness and thermal conditions.