Houshang Shahnavaz

Musculoskeletal Symptoms as Related to Ergonomic Factors in Iranian Hand-Woven Carpet Industry and General Guidelines for Workstation Design

Carpet weaving is a high risk occupation for developing musculoskeletal disorders (MSDs). The objectives of the present study, which was carried out in theIranian hand-woven carpet industry, were determination of the prevalence of MSD symptoms, identification of major factors associated with MSD symptoms and development of guidelines for workstation design. 1,439 randomly selected weavers participated in this study. A questionnaire was used to collect data on MSD symptoms. The results revealed that the prevalence rates for symptoms in different body regions were high as compared to the general Iranian population (for neck, back and large joints, p < .0001). The results of multivariate analyses showed that major ergonomic factors associated with musculoskeletal symptoms were loom type, working posture, daily working time and seat type. Based on the results, some general guidelines for designing weaving workstations were developed. A prototype test showed that the new workstation was acceptable for subject tests and that it improved working posture.

Workplace injuries in the developing countries

Transfer of technology and industrial development without consideration for the characteristics of the local users and the environmental conditions of the recipient countries has proved to be not only socially destructive but economically expensive in terms of human suffering and material losses Most developing countries (DC) are paying an unacceptably high price in terms of suffering, sickness and also loss of production due to work-related accidents Poor working conditions and non-existence of an effective injury prevention programme in many DCs has resulted in a very high sickness and accident rate. In such circumstances, the salary and social benefits of the worker are low, because productivity is well below its capacity. This vicious cycle also results in the workers malnutrition and low working capacity, resulting in turn in greater vulnerability to disease and job-related accidents A greater awareness is needed among employers and the workforce of such common problems as increased health hazards, ...

Ergonomics evaluation of modified industrial helmets for use in tropical environments

Hotness, weight, fitting problems etc., have been found to be the chief causes of the unpopularity of industrial safety helmets in tropical environments in developing countries (DC). Some selected safety helmets manufactured in industrialized countries (IC) were modified to provide extra head ventilation and to reduce weight, in order to make them more acceptable to users in hot environments. The modified helmets were subjected to ergonomics evaluation both objectively and subjectively in the laboratory (in simulated tropical conditions) as well as in the field situation. There was evidence that white helmets had some advantages in comfort, viz. reduction of hotness, compared to the other colours, e.g. red, green etc., when worn in the presence of radiant heat in the laboratory. Ventilation holes provided at the top of the shell seemed to reduce the greenhouse effect within the helmet shell which therefore felt less uncomfortable than a fully covered helmet. Even with a small reduction of weight, such as ...

Major health risk factors in Iranian hand-woven carpet industry.

This paper reviews the role and importance of small-scale industries together with the issue of occupational health problems and their causes in Iranian hand-woven carpet industry as a typical informal small-scale industry in an industrially developing country. The objective ofthis paper is to review health risk factors and related occupational health and ergonomic problems in the carpet industry. Since the overwhelming majority of weavers’ health problems originate from ergonomic risk factors, it is concluded that any improvement program in this industry should focus on ergonomic aspects. To assess ergonomic conditions in weaving workshops, a checklist has been developed and an ergonomics index indicating the ergonomic conditions of the workshop has been proposed. To test and verify the checklist, 50 weaving workshops were visited and their ergonomic conditions were assessed. Based on the results some modifications were made and the checklist was shown to be an effective tool.

Body size variability between people in developed and developing countries and its impact on the use of imported goods

The Industrially Developing Countries (IDC) today, to a great extent, depend on Industrialized Countries (IC) for the supply of most industrial goods. An attempt has been made to ascertain the degree of design incompatibility experienced by users of these imported goods due to differences in the body sizes of people in producer and user countries. A comparative study of variations in body sizes is made from data available in literature and from anthropometric surveys. The results reveal differences in almost every part of the human body. The need for reliable anthropometric data in respect of IDC is stressed. Urgent measures are required to introduce changes in equipment, particularly for the benefit of users in IDC.

Adaptation to discomfort in personal protective devices: an example with safety helmets.

Discomfort in the use of personal protective devices (PPD) has been one of the chief causes of their non-use. A field trial using industrial helmets was carried out to ascertain whether by training and repeated wearing subjects could experience a significant adaptation to discomfort. Ten subjects took part in the trial in a tropical environment by wearing helmets repeatedly (6 h a day) for one month. Subjective evaluations of discomfort were made at the end of the 1st, 3rd, 5th, 14th and 30th day. It was revealed that complaints of discomfort, viz. hotness, heaviness, bad fit, etc., decreased markedly throughout the 30 day period. Though positive responses of adaptation to discomfort seem to reach an optimum towards 30 days, it is difficult to draw any conclusions on the optimum period of adaptation for each discomfort factor. In relation to inherent discomforts that are extremely difficult to overcome without compromising the protection efficiency of a PPD, the principle of adaptation seems to be a very important facet which has to be developed for an effective PPD programme.

Interactive effect of ergonomics and production engineering on shoulder-neck exposure — A case study of assembly work in China and Sweden

Abstract Ergonomic improvements of work station design have been widely embraced as a measure for reduction of physical work load (mechanical exposure) and prevention or control of occupational shoulder-neck disorders. However, other elements of work rationalization, more in the hands of production engineers, may also influence the mechanical exposure. The present study concerns shoulder-neck exposure in a Chinese and a Swedish assembly line workplace. Interactive effects of ergonomic work station design, and production engineering (in terms of assembly line balancing and sensitivity of assembly line layout to production irregularities) on shoulder-neck exposure have been studied. It was shown that the Swedish workplace has a better ergonomic work station design, reflected in more favorable work postures during assembly operations. At the same time, the Swedish assembly line is better balanced and less sensitive to production irregularities, which probably reduces the total duration of idle time during assembly compared with the Chinese line. On the Swedish assembly line, arm movements are more frequent, and trapezius and infraspinatus muscle activation is more repetitive. Muscle activation levels are similar on the two lines. However, a larger proportion of low level muscle activities were found on the Chinese line compared with the Swedish line. On the basis of these results, it is suggested that the mechanical exposure of the assembly workers is a result of counteracting effects of improved ergonomic design of work stations and more effective production engineering. Relevance to industry This paper suggests that not only traditional ergonomic work station design but also production engineering are importajt determinants of shoulder-neck exposure during assembly work.

Subjective evaluation of three helmets in cold laboratory and warm field conditions

Abstract Helmets are widely used in industries as a primary protection means for workers. Helmets can provide efficient protection against occupational hazards to the head, they also cause thermal discomfort to the wearers at work. To develop a reliable heat transfer testing method for helmets any objective testing method must be validated with subjective testing of the same helmets. Subjective evaluation of helmet heat transfer properties was conducted in both cold and hot conditions using three commonly used and commercially available helmets. Twenty-five subjects participated in a laboratory investigation in a simulated cold environment (+3°C and 30% RH); forty-three steel-making workers participated in a field survey in the hot environment (31°C and 32% RH). Subjects were either asked to conduct certain tasks (in the laboratory investigation) or performed their regular production duties (in the filed survey) while wearing a helmet; they were then asked to answer questions in a questionnaire at the end of the surveys. The results of the subjective assessment which were compared with the objective measurements taken on a sweating manikin head using the same helmets, were found consistent. Relevance to industry Thermal discomfort in protective helmets prevents the acceptance and function of head protection devices in industries. Evaluation of heat transfer properties of helmets can provide design basis and suggestions to helmet manufacturers to produce thermally comfortable and well acceptable head protections.

Lighting conditions and workplace dimensions of VDU-operators.

Environmental conditions such as lighting and dimensions of the workplaces and factors related to Visual Display Units have been measured during day and night shifts for 28 operators at a telephone information centre. The results of the survey show that operators have preferred, in general, much lower luminance and workplace illuminance than previously reported in the literature. The study also revealed large interindividual differences in screen and workplace lighting adjustment.

Prevalence of Musculoskeletal Disorders at Workplaces in the People’s Republic of China

This paper presents 2 musculoskeletal disorders questionnaire surveys in 10 different Chinese occupational groups. Data collected from 1,603 workers using a modified Nordic musculoskeletal disorders symptom questionnaire showed that the 12-month prevalence of musculoskeletal disorders, particularly in the low back and shoulder-neck regions, was high at many Chinese workplaces. Significant differences existed between occupational groups. Assembly workers usually had higher neck-shoulder complaints compared to workers in most other occupations. However, the nature of assembly seemed also to influence the prevalence rate. Workers at a cassette recorder and a TV set assembly plant appeared to have more neck complaints compared with a group of thermos flask assemblers.