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Back injury interventions for small contractors.

Mirka-GA; Bernold-L; Dement-J; Lipscomb-H; Moon-S
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-CCR-413061, 2000 Sep; :1-92
The specific aim of this project was to study the effectiveness and the efficacy of ergonomic interventions for the reduction of low back injuries in small, residential contractors. Three trades identified in the literature as high risk occupations for low back injury were the focus of this study: masons, framing carpenters and drywall hangers. This research effort can be broken down into four research projects that were completed during the period of this grant. Project # 1 was to develop a low back biomechanical risk assessment model that is able to evaluate the physical demands placed on workers in the home building industry. The result of this work is the CABS risk assessment methodology. The strength of this new hybrid assessment tool is its ability to evaluate jobs with highly variable biomechanical demands. It is able to do this by using three well-established assessment tools: the Revised NIOSH Lifting Equation, the University of Michigan Three-Dimensional Static Strength Prediction Programs and the Ohio State University Lumbar Motion Monitor Model and then creating time-weighted histograms of each model's assessment of low back stress. This risk assessment tool was then employed in Project #2 to identify the high risk activities being performed by workers in each of the three trades. These activities were then prioritized by level of risk and the specific risk factors for each task were identified. The focus of Project #3, then, was to identify/develop ergonomic interventions designed to reduce or eliminate exposure to the specific identified risk factors. The philosophical approach to developing/evaluating ergonomic interventions for workers was to try and make use of as many existing tools/technologies as possible. This came in the form of using technologies "off the shelf" or finding ones that could be modified to be useful in the specific application. It was reasoned the we could make a significant contribution by performing a thorough analysis of these technologies and illustrate to the industry that their limited resources could be well spent on these items. Further, if we are able to modify an existing product to suit the purposes identified in Project #2, the likelihood that these tools could get to market and be useful is increased. Manufacturers might only have to make minor changes to their designs and open up a new market for their product lines, thus increasing the likelihood that these beneficial designs get to market. In total 18 different prototypes were developed in this phase of the project. Finally, Project #4 was a detailed ergonomic and productivity assessment of a subset of the most promising interventions developed in Phase #3. This process included gathering impressions from the workers. In total ten ergonomic interventions were evaluated in the field. The results of this analysis showed that, averaged across all interventions, there was a 40% reduction in peak spine compression and a 41 % reduction in average spine compression with the use of the interventions. The interventions for the framing carpentry tasks on average generated a 51 % and 53% reduction in peak and average spine compression values. These values for the masonry work (32% and 35% reduction) and drywall work (14% and 5% reduction) also showed improvement. The results with regard to productivity have shown that, of the ten ergonomic interventions evaluated in this study, seven had positive impacts on productivity, two had mixed effects on productivity and one had a negative effect on productivity. The increase in productivity averaged across all interventions was 28%. The subjective impre.ssions of the workers towards these interventions was mixed. In general, those interventions that improved productivity were enthusiastically embraced while those that slowed them down, regardless of how well it reduced the loads on the back, were not considered feasible.
Construction-industry; Construction-workers; Ergonomics; Back-injuries; Musculoskeletal-system-disorders; Environmental-factors; Weight-factors; Posture
The Ergonomics Laboratory, Department of Industrial Engineering, North Carolina State University, Raleigh, NC 27695-7906
Publication Date
Document Type
Final Grant Report
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Fiscal Year
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NIOSH Division
Source Name
National Institute for Occupational Safety and Health
Performing Organization
North Carolina State University, Raleigh, North Carolina 27695-7906