Ergonomic evaluation of technology change at work and its effect on health
Abstract: The change at work in the context of technology change has affected human’s health in relation to their working condition, attitude, and MSDs risk factors. These changes were included: adopting new tools, work concept work environments, and work system. Ergonomic methods, can be applied as tools for identify, evaluate these effects of the changes whether they give better health and work condition to workers. The purpose of this thesis is to apply the ergonomic methods to evaluate/identify the work conditions, MSD risk factors where the change at work existed for preventing MSDs in the context of technology change. This thesis compiled with 5 studies as followed: Study I, the Proprioceptive derivation (Pd) concept has introduced to Thai dentistry, and the aim of this study was to assess the working conditions and the attitude among experienced users. Questionnaires were distributed among 12 dentists. The results showed that the Pd concept seems to reduce the stress level of dentists, but the continuous sittingposture adopted is a risk for back pain in dentists, from the ergonomic point of view. The Pd concept with a dental bed can provide easy accessibility to patients with physical limitations and it results in a lower stress level among dentists. Most dentists who used Pd found it useful. Study II, the aim of this study was to investigate the differences in dentist’s working posture when adopting different work concepts: - Pd and Conventional concept. The observation methods and RULA assessment were applied. The result showed differences in dentists’ sitting posture, clock- related working position, and RULA score. It implied that Pd concept helps the dentists to discover new ways to position themselves, and working comfortably and effectively, which made it possible for the dentists to adopt better working posture and have lower RULA score. Study III, a redesigned cleaning tool was introduced to the cleaners. The physiological, trunk posture and subjective assessment were measured. The results found that floorcleaning in the train wagons is associated with moderately high cardiovascular load and high frequency of stressful working postures. An introduction of the redesigned cleaning tool allowed cleaners to maintain more upright posture while cleaning, which reduce biomechanical and physiological loads on them. Study IV, applied participatory ergonomic method for identification of the cleaning problems and to evaluate the effect of the low-cost improvement on the cleanersด working posture by using OWAS method. Results showed through participatory ergonomics method cleaning problem was identified, and ergonomic solution suggested by cleaners were implemented as low-cost improvement. A low-cost improvement has improved the working posture of cleaners by eliminating the awkward working postures such as sitting on one and two bent knees, and arm above the shoulder. Study V, ergonomic and production system effectiveness are evaluated in a case of a production system redesign: from parallel flow dock-based, to serial flow line-based assembly. The line-based system displayed much tighter coupling of operators to the technical system and introduced system, balance and downtime losses. We observed reductions in: cycle times to 6% of previous, decision latitude, influence and control over work, perceived work load, and perception of available pauses. Layout and technology changes helped improve co-worker interaction and support, and reduce instances, but not magnitude, of peak spinal loading. It is concluded that serial flows can negatively affect psychosocial conditions and, if losses are high, reduce physical workload. An ‘Action Group’ has been formed in the company to adopt an evidence-based approach to the development of systems that are sustainable from both productivity and ergonomics perspectives. In conclusion, technology changes can give both positive and negative effects on the humans’ health. Ergonomic methods can be used to evaluate these effects. Self-reported questionnaire can give the information on working condition, and attitude of the people working under the change in technology. RULA and OWAS were very useful for identifying and analyzing the postural risk factor. Direct measurement such as physiological responses was useful to identified work load on human body. Participatory ergonomic is also a very useful method for identifying problem, and possible solutions for improving the working conditions. Further, the results from ergonomic evaluation can provide useful information which is needed for future intervention or work-system design in each industry for preventing MSDs at the work place.
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