## 3 Results
### Exposure Time to Hazards According to Musculoskeletal Pain
#### 3.2.2 Hazard Exposure Related to Upper Limb Pain  
Figure 3 and Table 4 show the \(t\)-test results comparing daily hazard exposure between workers who complain of upper limb pain and those who do not. Regarding physical hazards, workers between groups show significant differences in their exposure times to vibration (\(t=-2.181\), \(p=0.030\)), noise (\(t=2.553\), \(p=0.011\)), high temperature (\(t=-2.102\), \(p=0.036\)), and low temperature (\(t=-3.666\), \(p<0.001\)). Workers with upper limb pain experienced a daily exposure time that was 1.454 (1.838/1.264) times longer for low temperature, 1.270 times longer for noise, 1.204 times longer for high temperature, and 1.192 times longer for vibration than those without pain.  
Among biochemical hazards, there was a significant difference in average daily exposure time between groups for chemical contact (\(t=-3.131\), \(p=0.002\)) and tobacco smoke (\(t=-3.052\), \(p=0.002\)). Those who reported upper limb pain had 1.124 times longer exposure to chemical contact and 1.071 times longer exposure to tobacco smoke compared to those who did not.  
In terms of ergonomic risks, there was a significant difference in daily exposure time between complainers and non-complainers of upper limb pain in awkward posture (\(t=-4.807\), \(p<0.001\)), handling heavy loads (\(t=-4.058\), \(p<0.001\)), and repetitive motion (\(t=-2.690\), \(p=0.007\)). Complainers of upper limb pain were exposed 1.405 times more  
Figure 2: Mean exposure times (hours per day) for back pain complaints. * Differences between groups exist at a significance level of 0.05 (red letters); error bars = standard deviation.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Factor**} & \multirow{2}{*}{**Hazard**} & \multicolumn{2}{c}{**No Pain**} & \multicolumn{2}{c}{**Back Pain**} & \multirow{2}{*}{\(p\)**-Value**} \\ \cline{3-3} \cline{5-7}  & & **Mean ** & & & **SD** & \\ \hline \multirow{4}{*}{Physical hazards} & Vibration & 2.293 & 2.245 & 2.698 & 2.425 & 0.051 \\  & Noise & 1.659 & 1.833 & 2.005 & 2.080 & 0.054 \\  & High temperature & 1.350 & 1.424 & 1.587 & 1.550 & 0.081 \\  & Low temperature & 1.328 & 1.510 & 1.882 & 2.160 & 0.002 * \\ \hline \multirow{4}{*}{Biochemical hazards} & Vapor & 0.858 & 0.331 & 0.921 & 0.444 & 0.083 \\  & Chemical contact & 0.837 & 0.229 & 0.923 & 0.513 & 0.029 * \\  & Tobacco smoke & 0.832 & 0.204 & 0.875 & 0.242 & 0.038 * \\ \hline \multirow{4}{*}{Ergonomic hazards} & Awkward posture & 2.448 & 2.155 & 3.371 & 2.469 & \textless{}0.001 * \\  & Handling heavy loads & 2.222 & 1.934 & 3.066 & 2.294 & \textless{}0.001 * \\ \cline{1-1}  & Standing posture & 4.378 & 2.352 & 4.454 & 2.500 & 0.725 \\ \cline{1-1}  & Repetitive motion & 4.303 & 2.491 & 4.488 & 2.411 & 0.404 \\ \hline \hline \end{tabular} Note. * significant at 0.05, ** hours per day, SD = standard deviation.  
\end{table}
Table 3: \(T\)-test results comparing daily hazard exposure between groups regarding back pain.  
in awkward posture, 1.335 times more in handling heavy loads, and 1.061 times more in repetitive motion than non-complainers.