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Purpose. Two groups of heavy earthmoving equipment operators, transport equipment (dumper) operators and non-transport equipment (drill and shovel) operators, in coal mines are assessed comparatively for their vibration magnitude and possible health consequences. Methods. Whole-body vibration exposure measurements were recorded according to Standard No. ISO 2631-1. Measurements were carried out at the operator-seat interface with a tri-axial seat pad accelerometer using a vibration analyser, followed by a questionnaire survey. The binary logistic regression model was used to comparatively assess the two groups of operators. Results. The binary logistic regression analysis revealed that the risk of lower back pain is 4.06 times greater (95% confidence interval [1.36, 12.08]) in transport equipment operators compared to non-transport operators. The daily vibration dose value of the transport equipment operators was 2.92 times greater than their counterparts (95% confidence interval [0.94, 9.09]). However, non-transport equipment operators belonging to the high driving experience category presented a value 5.26 times higher than the transport equipment operators. Conclusion. Transport equipment operators are more vulnerable to vibration hazards than their counterparts, as is evident from the vibration magnitude as well as from the symptoms of lower back pain.

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Whole-body vibration (WBV) is one of the leading risk factors for development of musculoskeletal disorders (MSDs) that develop symptoms of lower back pain, pain in the neck and shoulders, digestive problems, blood pressure and diabetes among professional dumper operators. The present study specifically aimed at assessing the WBV exposure of 79 dumper operators engaged in two Indian opencast coal mines through vibration measurements followed by questionnaire survey. From the daily frequency-weighted root mean square exposure, dumper operators have experienced vibration levels higher than the Health Guidance Caution Zone (HGCZ) of Standard No. ISO 2631-1:1997. However, on the basis of daily vibration dose values, 60.8% of operators have experienced vibration levels above the HGCZ. Finally, an attempt was also made to explore the potential of a Bayesian network to predict the risk factors for WBV of dumper operators in development of MSDs to prioritize the factors for human health risk assessment.

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BACKGROUND: This study aimed to assess the whole-body vibration (WBV) exposure among large blast hole drill machine operators with regard to the International Organization for Standardization (ISO) recommended threshold values and its association with machine- and rock-related factors and workers' individual characteristics. METHODS: The study population included 28 drill machine operators who had worked in four opencast iron ore mines in eastern India. The study protocol comprised the following: measurements of WBV exposure [frequency weighted root mean square (RMS) acceleration (m/s(2))], machine-related data (manufacturer of machine, age of machine, seat height, thickness, and rest height) collected from mine management offices, measurements of rock hardness, uniaxial compressive strength and density, and workers' characteristics via face-to-face interviews. RESULTS: More than 90% of the operators were exposed to a higher level WBV than the ISO upper limit and only 3.6% between the lower and upper limits, mainly in the vertical axis. Bivariate correlations revealed that potential predictors of total WBV exposure were: machine manufacturer (r = 0.453, p = 0.015), age of drill (r = 0.533, p = 0.003), and hardness of rock (r = 0.561, p = 0.002). The stepwise multiple regression model revealed that the potential predictors are age of operator (regression coefficient ß = -0.052, standard error SE = 0.023), manufacturer (ß = 1.093, SE = 0.227), rock hardness (ß = 0.045, SE = 0.018), uniaxial compressive strength (ß = 0.027, SE = 0.009), and density (ß = -1.135, SE = 0.235). CONCLUSION: Prevention should include using appropriate machines to handle rock hardness, rock uniaxial compressive strength and density, and seat improvement using ergonomic approaches such as including a suspension system.