| Abstract |
The manual material handling tasks in underground low seam mines present a myriad of ergonomic risk factors, which place inordinate demands on miners' neuromuscular system. Literature reports that serious injuries associated with handling material and slips or falls accounted for 36.4% (highest) and 16.4% (second highest), respectively, of all serious injuries. The mining industry requires work in restricted postures in mines with low-ceiling heights (low-seam mines). Material handling in restricted posture will cause potential of loss of stability/balance to increase; therefore, lifting task analysis should include information about postural stability/balance. Currently such information does not exist for material handling in astatic stooped/kneeling posture and dynamic (gait) stooped posture. The proposed study will provide this type of information. This information could be used for task analysis of material handling in mine site. The overall purpose of the study was to quantify postural instability of low seam miners while carrying out mine related tasks under exposure to individual and combined risk factors of environmental lighting, surface condition and footwear used. For this study, a total of 25 miner subjects were tested. Subjects (both males and females) were recruited from the United Mine Workers of America, (UMW A) District 17, Local 2264, Pikeville, KY as well as mines in Middlesboro, KY. Each subjects' postural stability was quantified while performing simulated mining tasks both in static (in a stationary position i.e. not walking) and dynamic (i.e. while walking) conditions under low seam ceiling. The quantification of postural stability during static condition constituted exposure to individual and combined risk factors of 3 types of surface So:(firm-dry DCOF: 0.90, uneven-dry DCOF: 0.59 and firm slippery surfaces DCOF: 0.22); 2 types of environmental lighting (poor and glare ); 2 types of postures (kneeling postures using I knee and 2 knees); 4 types of mining tasks (stationary, lifting buckets of bits, lifting cables and scaling). For the static condition all miners wore only one type of footwear (leather steel-toe boot). The quantification of postural stability during dynamic condition constituted the same risk factors as those used for static condition except for task type and footwear used. For the dynamic condition the footwear used were leather steel-toe boot and rubber steel-toe boot and task types were walking with and without weight (20 lbs). The results from the proposed study has now provided critical data to enhance an existing statistical model originally developed by us with NIOSH sponsorship [ R01-OH 002794 "Role of Postural Balance in Industrial Falls" (26)] showing the relationship between postural instability and/or loss of balance and the independent variables characterizing the Environmental and Job-Task factors for task performance in an environment simulating underground mines. The enhancement of the model will add the effects of new (currently not available in the model) risk factors of restricted posture, glare, kneeling, task type and uneven/slippery surface which are typically found in low-seam underground mines. In future field studies, this statistical model can be used to help evaluate the propensity for postural instability and/or loss of balance by measuring, in a walk-through evaluation, existing risk factors at the mining worksite. A determination of which of the risk factors need to be corrected to reduce the propensity for postural instability and/or loss of balance will then be possible. Availability of such models will have significant impact in identifying risk factors during job and workplace analysis of mining sites. Based on results from this study, improved work practices/training can now be developed to reduce the likelihood of workers' slips/falls while working in low seam mines. The results from this study can now be used to develop guidelines for mining workplace redesign to allow appropriate sufficient floor spacing so that workers can increase their base of support, minimizing the potential of postural instability. Results from this study can also be used to provide scientific data about postural instability under various combinations of workplace risk factors as input into the MSHA' s human factors, training program software. |
