Occupational Ergonomics - Volume 8, issue 2-3

Authors: Kozey, John W. | Brooks, Chris J. | Dewey, Sherma L. | Brown, Robert C. | Howard, Kimberly A. | Drover, Danika | MacKinnon, Scott | McCabe, John

Article Type: Research Article

Abstract: Representative samples of offshore workers engaged in the use of totally enclosed lifeboats were recruited in two different regions of Atlantic Canada for this study. Body mass, height and three selected anthropometric dimensions were measured with and without the presence of an immersion suit. Statistical comparisons were made between the two groups and to the main criteria values for body weight and space allocation used international standards for lifeboat capacity rating. There was no difference in the height, body mass and BMI values between the two groups. Both groups were found to be considerably heavier than the IMO Life Saving …Code standard of 75 kg. Not surprisingly, the shoulder breadths measurements were always greater than the hip breadth measurements. The seat pan allocation of 430 mm was found to be inadequate for this population and needs to be increased. Finally, the wearing of an immersion suit increases the physical size of each subject by substantial amounts. The magnitude of increase is related to the type of suit and whether there was external compression applied during the measurement. It was recommended that the international standard should be altered by reducing the lifeboat capacity ratings by 20%. Show more

Keywords: Human anthropometry, lifeboats, immersion suits, standards

DOI: 10.3233/OER-2009-0160

Citation: Occupational Ergonomics, vol. 8, no. 2-3, pp. 67-79, 2009

Authors: McClellan, Annie J. | Albert, Wayne J. | Fischer, Steve L. | Seaman, Fearon A. | Callaghan, Jack P.

Article Type: Research Article

Abstract: The purpose of this study was to complete in depth task analyses for a series of automobile parts assembly jobs and quantify the range of mechanical shoulder loading sustained by the workers. Nine jobs were selected from within an automobile parts assembly plant and 26 participants (12 males, 14 females) were filmed while they performed regular assembly line duties. Workers spent the majority of their time in neutral shoulder postures, and about 1/3 of the shift in mild shoulder flexion or abduction. Cumulative shoulder flexion moments ranged from 76–160 kNm*s while cumulative shoulder abduction moments ranged from 42–119 kNm*s. Peak …shoulder flexion moments ranged from 26–124 Nm and peak shoulder abduction moments ranged from 30–93 Nm. The analysis revealed a wide range of shoulder loading between jobs, and workers completing the same job. This study demonstrates the importance of measuring a variety of postural and mechanical demands for every job to adequately address all aspects of the work that might influence the development of injury. This is the first study to document entire shift cumulative shoulder moments during automotive parts assembly work. This quantitative assessment provides insight into the range of loading that workers are currently experiencing, and demonstrates the variability between workers completing the same task. Show more

Keywords: Shoulder posture, shoulder loading, cumulative loading, automotive assembly

DOI: 10.3233/OER-2009-0162

Citation: Occupational Ergonomics, vol. 8, no. 2-3, pp. 81-90, 2009

Authors: Bhattacharya, Amit | Succop, Paul | Kincl, Laurel | Gordon, Jessica | Sobeih, Tarek

Article Type: Research Article

Abstract: The manual material handling tasks in underground low seam mines present a myriad of ergonomic risk factors, which place inordinate demands on the miners' neuromuscular system. The mining industry requires work in restricted postures in mines with low-ceiling heights (low-seam mines). Material handling while in a restricted posture will cause an increase in the potential of loss of stability/balance to increase. Currently, such information does not exist for material handling while in a stooped/kneeling posture. The overall purpose of the study was to quantify postural instability of low seam miners while carrying out mine related tasks. For this study, a …total of 25 miner subjects were tested. Each subject's postural stability was quantified while performing simulated mining tasks under a low seam ceiling. The quantification of postural stability constituted exposure to individual and combined risk factors of 3 types of surfaces (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 one knee and two knees); and 4 types of mining tasks (stationary, lifting buckets of bits, lifting cables and scaling). Based on the results, the tasks of lifting of bits, cable lifting, scaling and stationary were ranked least to most stable as they relate to miners' postural balance, respectively. This finding is consistent with ranking of tasks producing the most to least number of observed slip events (during task performance) to be lifting of bits (19.4% slips observed), cable lifting (18.9% slips), scaling (16.3% slips) and stationary tasks (4% slips), respectively. Based on all the experimental conditions that were varied, the one knee posture was more unstable compared to the two-knee posture. A one-knee posture was rated higher in terms of both RPE and PSOS as compared to a two-knee posture, which is consistent with the objective measures of postural stability/balance. While consistency between subjective and objective measure supports the fact that miners were correctly judging the threat of instability associated with the one-knee posture, they were not successful in deploying appropriate and corrective postural responses to minimize slips during task performance with one-knee posture as this posture (as opposed to two-knee posture) produced the largest numbers of slips. This may suggest that a re-evaluation of the methods used to complete tasks be accomplished in order to develop changes in work methods that will minimize slips and/or falls during task performance. Show more

Keywords: Low seam mining task, postural instability, miners, loss of balance, base of support, perceived sense of slip and fall

DOI: 10.3233/OER-2009-0161

Citation: Occupational Ergonomics, vol. 8, no. 2-3, pp. 91-114, 2009

Authors: Davis, Kermit G. | Sobeih, Tarek M. | Succop, Paul | Jetter, William | Kotowski, Susan E. | Bhattacharya, Amit

Article Type: Research Article

Abstract: Slips and falls account for a significant number of injuries suffered by firefighters. Obesity may be a contributing factor to these slips and falls since many firefighters have become significantly heavier over the last decade. This study's objective was to determine whether obesity places firefighters at a higher risk of slips/falls by impacting postural balance. Thirteen firefighters – 6 obese and 7 overweight/normal, had their postural balance measured over a single shift (at 12-hour intervals). Each assessment contained three specific tasks: eyes open while standing, eyes closed standing on foam, and a dynamic reach task. The firefighters wore turnout gear …with and without SCBA. Obese firefighters were found to have less postural sway, particularly when their postural control systems were compromised. When standing on foam, obese firefighters reduced their sway area by 26% as compared to overweight/normal firefighters. Similarly, obese firefighters had an 18% decrease in postural sway during the reach task. In all, the results indicate obese firefighters compensated posturally, reducing the potential for external demands resulting in a slip or fall. The key issue is that the obese firefighters sampled in the current study were able to compensate under ideal situations, particularly when required to wear gear and equipment. Show more

Keywords: Postural balance, emergency response, personal protective equipment, slips and falls

DOI: 10.3233/OER-2009-0159

Citation: Occupational Ergonomics, vol. 8, no. 2-3, pp. 115-123, 2009

Authors: Levin, Erik | Macintosh, Deborah | Baker, Tanya | Weatherall, Mark | Beasley, Richard

Article Type: Research Article

Abstract: The objective of the research was to assess the effect on lower limb venous blood flow of sitting in two ergonomic chairs. In a cross-over design 12 healthy subjects had popliteal vein blood flow measured by Doppler ultrasound in different sitting positions, in the Aeron and airCentric chairs. Measurements were made lying prone, sitting with the leg flexed 90° and sitting with the leg flexed 120° in one chair, followed by the same measurements in the second chair, the order determined randomly. The primary outcome measure was popliteal vein peak systolic velocity. Simple paired t-tests and a mixed linear model …were used to compare blood flow between chairs and different sitting positions. For the Aeron chair, the prone to 90° position resulted in a reduction in peak systolic velocity from 27.8 to 3.5cm/s, adjusted difference 21.0 (95% CI 17.3 to 24.8), and for the airCentric chair from 21.4 to 3.7cm/s, adjusted difference 21.2 (95% CI 17.4 to 24.9). There was no statistically significant difference in peak systolic velocity between the two chairs, in the two sitting positions. There was a marked reduction in popliteal vein blood flow with sitting, but no significant difference in effect between the two ergonomic chairs. Show more

Keywords: Venous, blood flow, sitting, posture

DOI: 10.3233/OER-2009-0163

Citation: Occupational Ergonomics, vol. 8, no. 2-3, pp. 125-132, 2009