## 3 Results
### Self-Reported Overall Fatigue and Musculoskeletal Pains by the Degree of Hazard Exposure
#### 3.3.2 Self-Reported Backache by the Degree of Hazard Exposure  
Table 7 shows the distribution of self-reported backache by the degree of hazard exposure.  
There were significant differences between the backache complaining group and the non-complaining group in noise exposure (\(\chi^{2}=8.923\), \(p=0.012\)), high-temperature exposure (\(\chi^{2}=11.152\), \(p=0.004\)), awkward posture exposure (\(\chi^{2}=10.545\), \(p=0.005\)), manual material handling exposure (\(\chi^{2}=7.082\), \(p=0.029\)), and infection exposure (\(\chi^{2}=6.786\), \(p=0.034\)). The proportion of the backache complaining group increases as the degree of hazard exposure increases. Longer exposure to infectious material shows the highest rate of backache (21.1%).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Factor**} & \multirow{2}{*}{**Variables**} & \multicolumn{3}{c}{**ADHE**} & \multirow{2}{*}{\(\chi^{2}\) **Test**} \\ \cline{3-5} \cline{5-6}  & & \(<\)**2** & & \(2\)**-4** & & \\ \hline \multirow{5}{*}{Physical hazard} & Vibration & 14.6\% & 16.3\% & 26.6\% & \(\chi^{2}=8.834\), \(p=0.012\) * \\ \cline{2-6}  & Noise & 15.6\% & 23.0\% & 27.5\% & \(\chi^{2}=7.999\), \(p=0.018\) * \\ \cline{2-6}  & High temperature & 15.0\% & 17.9\% & 38.2\% & \(\chi^{2}=25.913\), \(p<0.001\) * \\ \cline{2-6}  & Low temperature & 19.5\% & 20.8\% & 29.7\% & \(\chi^{2}=3.378\), \(p=0.185\) \\ \hline \multirow{5}{*}{Ergonomic hazard} & Awkward posture & 12.0\% & 17.1\% & 30.5\% & \(\chi^{2}=19.526\), \(p<0.001\) * \\ \cline{2-6}  & Manual material handling & 16.0\% & 16.9\% & 35.5\% & \(\chi^{2}=18.187\), \(p<0.001\)* \\ \cline{2-6}  & Standing posture & 11.7\% & 20.2\% & 23.2\% & \(\chi^{2}=4.062\), \(p=0.131\) \\ \cline{2-6}  & Repetitive motion & 8.5\% & 6.0\% & 24.9\% & \(\chi^{2}=14.407\), \(p=0.001\) * \\ \hline \multirow{5}{*}{Chemical and biological} & Fumes and dust & 13.2\% & 21.1\% & 42.2\% & \(\chi^{2}=37.465\), \(p<0.001\) * \\ \cline{2-6}  & Vapor & 17.5\% & 33.3\% & 36.6\% & \(\chi^{2}=13.235\), \(p=0.001\) * \\ \cline{1-1} \cline{2-6}  & Skin contact with chemical & 17.6\% & 21.9\% & 48.8\% & \(\chi^{2}=21.427\), \(p=0.001\) * \\ \cline{1-1} \cline{2-6}  & Tobacco smoke & 18.9\% & 26.1\% & 52.6\% & \(\chi^{2}=13.155\), \(p=0.001\) * \\ \cline{1-1} \cline{2-6}  & Infection & 19.3\% & 30.4\% & 47.4\% & \(\chi^{2}=9.867\), \(p=0.007\) * \\ \hline \hline \end{tabular}
* * Significant at 0.05. ADHE = adjusted daily hazard exposure time.  
\end{table}
Table 6: Distribution of subjective overall fatigue by the degree of hazard exposure.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Working Hours**} & \multicolumn{5}{c}{**Musculoskeletal Pains**} & \multirow{2}{*}{**Overall Fatigue**} \\ \cline{3-5} \multicolumn{2}{c}{**(Hours)**} & \multicolumn{1}{c}{**Backache**} & \multicolumn{1}{c}{**Upper Limb Pain**} & \multicolumn{1}{c}{**Lower Limb Pain**} & \multicolumn{1}{c}{**Any Pain**} \\ \hline \multirow{2}{*}{\(<\)41} & N = 272 & 20 & 52 & 27 & 64 & 46 \\ \cline{2-6}  & \% & 7.4\% & 19.1\% & 9.9\% & 23.5\% & 16.9\% \\ \hline \multirow{2}{*}{\(\geq\)41} & N = 174 & 14 & 48 & 25 & 58 & 48 \\ \cline{2-6}  & \% & 8.0\% & 27.6\% & 14.4\% & 33.3\% & 27.6\% \\ \hline \multirow{2}{*}{Total} & N = 446 & 34 & 100 & 52 & 122 & 94 \\ \cline{2-6}  & \% & 7.6\% & 22.4\% & 11.7\% & 27.4\% & 21.1\% \\ \hline \multirow{2}{*}{\(\chi^{2}\) test} & \(\chi^{2}\) & 0.072 & 4.375 & 2.032 & 5.133 & 7.269 \\ \cline{2-6}  & \(p\) & 0.788 & 0.036 * & 0.154 & 0.016 * & 0.007 * \\ \hline \hline \end{tabular}  
* Significant at 0.05. Note: Any pain = Pain complaints in any one area.  
\end{table}
Table 5: Distribution of subjective musculoskeletal pains and overall fatigue by working hours.