Journal of Health and Safety at Work

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Introduction: The power tiller is a multipurpose hand tractor designed primarily for rotary tilling and other farm operations. Vibration, transmitted from the handles of the tiller to the operators’ body, causes many injuries such as, pain, musculoskeletal disorders and white finger syndrome. The aim of this study was to evaluate the hand-arm vibration exposure in the operators of tiller model HT900, as the most frequently used model of tillers.

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Material and Method: In this study, 40 operators tiller of model HT900 in the city of Kashmar, Khorasan Razavi were examined. Hand-arm vibration measurement was done according to ISO 5349-1 and ISO 5349-2 in three different modes including, static and neutral (mode), transition to the ground mode and plowing the land mode in different gears. In order to measure the vibrations, human response vibration meter of B and K model 2512 was utilized.

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Result: Results of the present study indicated that in all measured situations, exposure to hand arm vibration was higher than the standard limit suggested by Iranian occupational health committee and there was risk of vibration-induced disorders. The maximum exposure to vibration is in plowing ground. Exposure to hand arm vibration in three modes of plowing, transmission and natural, were respectively 16.95, 14.16 and 8.65 meters per second squared. Additionally, in all situations, vibration exposure was highest in the X-axis in comparison with Z- and Y-axes.

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Conclusion: This study emphasizes on the need to provide intervention and controlling and managing strategies in order to eliminate or reduce vibration transmitted from tiller to operators hand and arm and also prevent to serious problems including neurovascular disorders, discomfort and white finger syndrome. Meanwhile, more studies are necessary to identify the sources of vibration on different models of tiller.

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Introduction: Long-term exposure to hand-arm vibration causes musculoskeletal disorders mainly in hand and shoulder. The purpose of this study was to determine the effect of sport and using anti-vibration gloves on the grip strength of workers exposed to the hand-arm vibration.
Material and Methods: In this descriptive-interventionist study, 41workers working in one of the Isfahan metal industries were studied. Data were collected by the demographic questionnaire, hand-arm vibration acceleration measurement was performed based on the ISO 5349 standard and grip strength was measured using the dynamometer device model Jamar. The investigations were performed on 3 groups including sporting moves, using of anti-vibration gloves and combination of sporting move and using of gloves. Twenty workers were selected as control group without exposure to any hand-arm vibration. Data were analyzed by the SPSS-21 software.
Results: Workers’ grip strength difference was significant before and after vibration (PValue<0.001) and grip strength had significant and inverse relation with vibration (PValue<0.001, R= -0.411). Grip strength was higher in the group that used anti-vibration gloves accompanied with the sporting moves compared to before the intervention and significant relation was observed (PValue<0.001).
Conclusion: Vibration affects decreasing in grip strength and grip strength itself can be used as a screening measure for those workers exposed to the risk and diseases related to the vibration. Regular sporting moves and using anti-vibration gloves are effective on improvement of workers’ grip strength and preventing vibration-induced complications.

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Introduction: This study aims to determine the amount of hand-arm vibration transmitted from heavy electric destruction tools and the effect of using chisel with different lengths and shapes when demolishing concrete surfaces.
Material and Methods: To evaluate the magnitude of hand-arm vibration on the left and right handles of two powerful electric demolition hammers commonly applied in Iranian construction work and urban services, 323 measurements were made (RONIX and NEC). The demolition procedure was carried out by two experienced users on 49 concrete slabs of the same grade (20 C) with thicknesses of 10 and 15 cm while utilizing standard tools, such as hammers with two different chisel head shapes (flat and point) and lengths (40 and 60 cm). Utilizing two SVANTEK vibration meters concurrently on each hammer handle, measurement and evaluation were according to the ISO 5349:1, 2 procedures.
Results: The mean effective (frequency weighted root mean square) acceleration (awrms) for the Vector Sum Values (VSV) in the hammer handles were 15.71 m/s². The primary vibrational axis transmitted to the handle of tool was the vertical axis, at 13.60 m/s². When employing flat and point chisel, the mean awrms were 16.59 m/s² and 14.82 m/s², respectively. The difference between the results of 60 and 40 chisel was a little more than 2m/s2. The dominant and harmonic frequencies of the tools were generally in the range of 25 Hz to 80 Hz and 200 Hz to 400 Hz
Conclusion: The mean results generally indicated that point chisel with shorter lengths (40 cm) accelerates at a lower rate than flat chisel with longer lengths (60 cm). In the frequency range below 40 Hz, the RONIX hammer produced a larger acceleration than the NEC hammer indicating that the NEC hammer had a higher safety competitive advantage compared to the another hammer.