Journal of Health and Safety at Work

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Introduction: Low back pain is one of the most common musculoskeletal disorders leading to disability around the world. Several studies have suggested that prolonged computer/ laptop work contributes to the development of low back pain and discomfort. The results of the studies conducted on the association of back discomfort and muscle activity are contradictory. Thus, the present study aims to evaluate the relationship between the activity level and relative rest time of the trunk muscles with back discomfort while working with a laptop in a sitting position.
Material and Methods: First, 20 young healthy males performed laptop work including mouse work and typing in conventional and ergonomic setups. In the ergonomic setup, the screen height and keyboard placement were specifically adjusted for each individual. In addition, the electromyographic activity of the lumbar erector spinae, right and left multifidus and transversus abdominis, rectus abdominis, external oblique muscles, and the posture of the lumbar spine were recorded in the first and last two minutes of an 8-min task. After the end of each task, the participants scored their back discomfort.
Results: The results showed a positive correlation (r=0.57 and p=0.009) between back discomfort and the EMG amplitude of the lumbar erector spinae muscle. In addition, back discomfort was negatively correlated to the relative rest time of the multifidus muscle (r=0.50 and p=0.023), and a positive correlation was reported with the relative rest time of the transversus and rectus abdominis (r=0.47, p=0.039, and r=0.45, p=0.049, respectively).
Conclusion: The relative rest time of the trunk muscles may be a better index than that of the EMG amplitude to highlight the risk factors for back discomfort. However, a causative link between muscle activity and discomfort cannot be implied from this study. The current results do not undermine the role of other factors associated with the increased level of discomfort during sitting.

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Introduction: With the advancement of industries and increased use of metalworking fluids, controlling pollutants generated by machining operations has become increasingly challenging. This study aimed to address these challenges by designing an air filtration system designed specifically for this purpose.
Material and Methods: A local exhaust ventilation system was developed based on the VS-80-12 ACGIH standard, tailored to the working conditions and air sampling of the environment. The filtration system includes an aluminum pre-filter, an E11 class filter, and a nanofiber filter incorporating a metal-organic framework. The performance of the system was evaluated by measuring the numerical concentration of particles and the mass concentration of oil mist at both the inlet and outlet. The results were then compared to those obtained from an E1 class filter.
Results: The results obtained from XRD and FTIR analyses showed that ZIF-8 had high crystallinity and was successfully incorporated into the structure of the fibrous media filter containing metal-organic framework. The evaluation revealed that the filtration system effectively removed pollutant particles at their source. Notably, the initial efficiency for larger particles reached 100%, while the average removal efficiency for particles smaller than 2.5 microns was 99%.  
Conclusion: In conclusion, the combination of nanofiber filters with a metal-organic framework and aluminum pre-filters presents an effective solution for controlling particulate pollutants from machining operations. However, further research is necessary to comprehensively assess the system’s performance, particularly regarding dust loading capacity. Future studies should also explore the effects of various factors, such as airflow rate and the type of metalworking fluid, on the system’s efficacy.