Study and analysis of occupational risk factors for ergonomic design of construction worksystems

Manual material handling (MMH) is unavoidable because of the nature of jobs or tasks as and man-machine interfaces in a construction worksystem. Data were collected from six strata of workers viz., masons, mason helpers, carpenters, welders, gas cutters and ground-level helpers (259 out of 700 workers) from a construction site of a steel plant located in India to analyze different types of occupational risk factors, such as awkward posture, repetitive movements and others associated with MMH activities to assess their impact on musculoskeletal disorders (MSDs). It is essential that these risk factors are required to be under control through application of ergonomics-based design approaches for construction worksystem. In this context, multinomial logistic regression analyses were used to identify the significant risk factors among the workers. The results shows that masons, mason helpers, carpenters, welders/gas cutters and ground-level helpers are greatly affected by static body posture, type of tools used, excessive stress due to repetition, awkward postures and extreme climate, respectively. Appropriate preventive and corrective measures are suggested for minimization of risks associated with such jobs/tasks to improve health and performance of the workers.     

Ergonomic design of crane cabins: a case study from a steel plant in India

The study, carried out at the Batch Annealing Furnace (BAF) shop of Cold Rolling Mill (CRM) at an integrated steel plant of India, concerns ergonomic evaluation and redesign of a manually-operated Electrical Overhead Travelling (EOT) crane cabin. The crane cabin is a complex worksystem consisting of the crane operator and twelve specific machine components embedded in a closed workspace. A crane operator has to perform various activities, such as loading and unloading of coils, setting and removal of convector plates, and routine maintenance work. Initially, an operator had to work in standing posture with bent back most of the time. Ergonomically poor design of the chair and the controls, awkward work postures, and insufficient vision angle resulting in musculoskeletal disorders (MSDs) are some of the critical problems observed.. The study, conceived as an industry-academia joint initiative, was undertaken by a design team, the members of which were drawn from both the company concerned and the institute. With the project executed successfully, a number of lessons, such as how to minimize the anthropometric mismatch, how to improve the layout of the components and controls within enclosed workspace, and how to improve work posture minimizing risk of MSDs have been learned.     

Ergonomic evaluation in a values transportation company in Venezuela

The objective was to analyze the work activity and identify risk factors that could account for musculoskeletal disorders in the upper extremities, shoulder and neck of workers of a transport values company in Venezuela. The methods used were: collective interview, tasks observation, evaluation of posture with RULA method and evaluation of repetitive motions with the OCRA method. Five workstations were evaluated. Main problem perceived by workers was: exposure to chemical and biological hazards when handling paper money and coins; inadequate chairs and close supervision. The postures level risk was 1 or 2 for the RULA scale. Only two workstations showed ligth and medium risk level by OCRA method. Conclusion: The factors identified that could explain the musculoskeletal changes were: wrist repetitive flexion and extension, shoulder elevation, lifting weight above shoulder height, elbow repetitive flexion and extension, neck flexion, extended work journey, work overload, high responsibility and strict supervision by a video camera.     

Biomechanical modelling and evaluation of construction jobs for performance improvement

Occupational risk factors, such as awkward posture, repetition, lack of rest, insufficient illumination and heavy workload related to construction-related MMH activities may cause musculoskeletal disorders and poor performance of the workers, ergonomic design of construction worksystems was a critical need for improving their health and safety wherein a dynamic biomechanical models were required to be empirically developed and tested at a construction site of Tata Steel, the largest steel making company of India in private sector. In this study, a comprehensive framework is proposed for biomechanical evaluation of shovelling and grinding under diverse work environments. The benefit of such an analysis lies in its usefulness in setting guidelines for designing such jobs with minimization of risks of musculoskeletal disorders (MSDs) and enhancing correct methods of carrying out the jobs leading to reduced fatigue and physical stress. Data based on direct observations and videography were collected for the shovellers and grinders over a number of workcycles. Compressive forces and moments for a number of segments and joints are computed with respect to joint flexion and extension. The results indicate that moments and compressive forces at L5/S1 link are significant for shovellers while moments at elbow and wrist are significant for grinders.     

Psychosocial indicators among aircraft maintenance workers with and without neck and shoulder musculoskeletal symptoms

In the aircraft maintenance industry, most of workers performs manual handling tasks of different materials, varying from small objects up to large pieces of the aircraft. It can increase the occurrence of work-related musculoskeletal disorders (WMSDs), which are strongly associated with high physical demands required by the task. Moreover, psychosocial demands are considered as risk factors for musculoskeletal disorders in both the upper limbs and lumbar spine. Thus, the objective of this study was to assess psychosocial indicators among aircraft maintenance workers according to the presence of neck and shoulder musculoskeletal symptoms. Eighty workers of an aircraft maintenance company were evaluated (32.69 ± 8.25 years, 79.8 ± 13.4 kg, 175 ± 7 cm). According to physical examination, 50 workers were classified as asymptomatic (AS - 4.1 ± 3.17 positive signs) whilst 30 workers were classified as symptomatic (SS - 26.72 ± 11.44 positive signs). AS and SS have shown similar profile of demand (p = 0.62), control (p = 0.66) and social support (p = 0.74) according to the Job Content Questionnaire. However, the groups are different when considering work engagement variables. In general, SS have higher scores than AS (p < 0.05).     

Mitigation of musculoskeletal problems and body discomfort of agricultural workers through educational intervention

Farming is a physically arduous occupation that places farm workers' at potential risk of musculoskeletal disorders, which has been observed to impose a greater impact on their health. Each activity in agriculture brings about certain stress and strain on bones and muscles leading to work-related musculoskeletal disorders which can lead to several permanent diseases and disabilities. The purpose of analyzing musculoskeletal problems among male and female workers engaged in agriculture was to know about the risk factors dangerous to health so that interventions can be planned for mitigating them thereby increasing the efficiency of work. Educational intervention included audio-visual aids as well as printed literature. It was hoped that awareness of these factors through dissemination of information would contribute at preventing hazards amongst farmers and their families. The results revealed that the workers reported very severe to severe pain in low back while performing agricultural activities. Weeding was the most strenuous activity for females and threshing crop for males. Training and education on MSDs through educational intervention proved that the knowledge of the farm workers could be enhanced and can help reduce risk of many musculoskeletal problems. It can be help in empowering the community and mitigate MSDs in agriculture.     

Evidence-based exposure criteria for work-related musculoskeletal disorders as a tool to assess physical job demands

Despite worldwide attention, musculoskeletal disorders (MSDs) remain a substantial concern at work. To support ergonomists to assess the work-related risk factors for MSDs, several instruments are available. Unfortunately, many of these instruments are not supported by evidence-based exposure criteria for particular MSDs. For effective prevention of MSDs, it is important to know to what extent work-related risk factors are present in the work situation. The Netherlands Center for Occupational Diseases (NCOD) develops evidence-based criteria documents for the assessment of work-related MSDs. The exposure criteria of these documents can be used on a group level to support ergonomists in their assessment of the physical job demands that are associated with work-related MSDs. At the moment the NCOD has exposure criteria for the assessment of 22 work-related MSDs, for instance on the work-relatedness of upper extremity disorders, non-specific low back pain or patellar tendinopathy. The use of these exposure criteria enables ergonomist to better assess the work-related risks of MSDs as a starting point for effective prevention.     

Ergonomic basket design to reduce cumulative trauma disorders in tea leaf plucking operation

Work related musculoskeletal disorders are seen as an indicating parameter of occupational stress among the women workers engaged in tea leaf plucking operation. The hand plucking (no mechanized plucking is practiced in Assam) being a highly repetitive task requires forceful exertions to reach to the distant periphery of the tea bushes and mechanical compression (pressing against hard surfaces). Specifically it aggravates with awkward positions adopted. The current research addresses to minimize the risk factors associated with CTDs and to ascertain the role of ergonomic design development in improving the situation. Women workforce engaged in tea industry in Assam suffer from back, shoulder, arm and finger pains. Workers perform the activity for 440 minutes in the entire shift with one hour lunch break in between in the garden itself. An ergonomic investigation aiming at studying the strain index of plucking operation in tea industry was conducted. While performing the operation workers were found to assume unnatural posture which is static as well as highly dynamic with a load (tea leaf collecting basket up to weight of 30 kg when filled with plucked leaves) at back. With gradual increment of load and pain though the load is released intermittently the strain level found to remain at a high level. The total QEC scores found for plucking activity was 110 out of 138. To improve the situation and to reduce the work related upper limb disorder (WRULD) an ergonomically designed basket was conceived and trial results showed improvements. The newly designed plucking basket fits the back curvature of the workers well, which keeps the basket in place unlike the existing round basket. The new basket is light in weight having more leaf capacity. Significant reduction in energy expenditure and MSDs suffered was observed while using improved basket over existing basket.     

A comprehensive work injury prevention program with clerical and office workers: phase I

The risk for the development of musculoskeletal disorders and associated conditions in clerical and office workers is well documented. The majority of work injury prevention programs for this population were single-faceted (education, workstation redesign, or task modification) and yielded both positive and negative findings. This pilot study was conducted with 16 full-time clerical and office workers at a small private college. In a randomized control trial, the intervention group received four hours of individualized training through a multi-faceted injury prevention program. Between group differences in musculoskeletal symptom frequency and intensity and perceived stress and energy levels existed, although were statistically insignificant. There was a statistically significant decrease in Lower Back ache/pain from pre to post measures for the intervention group.     

The implementation of motor learning principles in designing prevention programs at work

Occupational therapy practitioners offer services to workers in the workplace to prevent musculoskeletal disorders (MSDs), to help the injured worker restore function, and to recover capacities needed to return to the job. Despite the existence of some evidence about the efficacy of prevention programs, there is uncertainty and even disagreement among health professionals, about the outcome of prevention programs for people with MSDs. It is proposed that principles of motor learning can assist the therapist in structuring prevention programs to facilitate the workers learning of correct movement patterns. This paper discusses basic concepts of motor learning emphasizing characteristics of the learner, the type of task, the structure of practice and application to prevention programs at work settings. We present a four-stage model for prevention programs based on principles of both motor learning and ergonomics. This model coincides with the broad perspective suggested in current occupational therapy models which focuses on the person, the environment, the occupation and their effects on occupational performance.     

A collaborative effort to apply ergonomics to electric utility workers at generating stations

As part of a collaborative approach involving electric utility companies, university researchers, individual contractors and a not-for-profit research institute, two ergonomics teams consisting of skilled utility workers and trained ergonomists, were assembled. These teams were to identify tasks with risk factors for musculoskeletal disorders (MSDs) among workers in fossil-fueled generating stations and and to propose ergonomic interventions for these tasks. One team focused on tasks of electricians and the other focused on tasks of plant operators and mechanics. Several of the tasks were tested in an ergonomics laboratory and at one of the utility's generating stations. We present a sample of the recommended interventions in this paper. An anthropometric analysis of electrical box height recommended the appropriate height for electrical boxes. The results of a field experiment showed that low rolling resistance wheels decreased the forces to initiate and sustain pushing a cart. The same experiment also demonstrated that the forces required to turn a cart with six wheels were lower than the forces equired to turn a cart with four wheels. A collaborative approach to ergonomics proved to be an effective method to identify and assess tasks that are problematic for workers and to develop best practices for these tasks in the electric power industry. This method could be used by other industries in their attempt to decrease the incidence, cost and severity of workplace MSDs.     

Workers' postural conditions in the charcoal production proccess based on vertical metallic cylynders

Considering the importance of posture to the workers' health in the production of charcoal, this paper presents an ergonomic research based on a biomechanical focus that aims to evaluate the posture adopted by these workers on the production of charcoal in vertical metallic cylinders. Thus, it was verified the incidence of pain and/or musculoskeletal injuries to these workers. Also, it was evaluated the weight carried by them and the positions taken in their daily tasks. Applying the Ergonomic Analysis of Labor, the data collection was done by directly observing the workers, registering images, by interviews, and posture analysis based on the OWAS method. The main results of the research show that there are postures with risks in the four levels of musculoskeletal injuries classified by OWAS, concluding that the method is imperative for ergonomic recommendations for minimization or eradication of suffering injury and worker's postural constraints.     

Ergonomic recommendations and their role in cardiac sonography

Musculoskeletal disorders (MSDs) have been recognized as a serious hazard to the health and safety of sonographers. Recommendations have been made on ways to reduce and prevent the frequency and severity of these disorders. The purpose of this study was to ascertain the impact ergonomics has had on the prevalence of MSDs among cardiac sonographers. Three hundred randomly selected Registered Diagnostic Cardiac Sonographers were surveyed. Eighty-one respondents completed the survey. The majority of the sample population was female with an average age of 40 and job tenure between 6-15 years. Ninety percent of respondents reported musculoskeletal pain/discomfort while scanning. Seventy-three percent of respondents perceived a need for ergonomic interventions. The majority of respondents were aware of previously recommended ergonomic interventions and had implemented what was feasible. Still, the experience of pain and discomfort, and incidence of MSDs remains exceptionally high for this occupation. It appears that recommended ergonomic interventions have not had a significant impact on improving the health and safety of cardiac sonographers.     

A field experiment comparing mechanical demands of two pruners for flower cutting

Manual flower cutting requires repetitive forceful movements that may explain the high incidence of upper-extremity MSDs among workers of the Colombian flower industry. Force demands may be caused by the use of pruners that have not been designed for Colombian workers. We conducted a repeated measures field experimental study (n=16, 69% women, 20 to 60 years old) to compare the mechanical demands during rose cutting of two different pruners (Traditional vs. alternative pruner) at two different cutting heights (elbow vs. over-shoulder). Demands included the perceived comfort, perceived effort and upper limb's muscular activity and posture. Workers perceived their traditional pruner as more comfortable but requiring more effort than the prototype tool. No benefits were observed regarding ulnar deviation with the alternative pruner. The wrist extension and related muscular activity of the wrist extensors were higher with the prototype pruner. The prototype pruner resulted in reduced muscular load of the wrist flexors; the biceps when working at the elbow height; and the deltoids when working at the shoulder height. However, Moderate results may be explained by the lack of time for workers' adaptation to the alternative tool. New design developments must focus on reducing extension and ulnar deviation of the wrist.     

Eye- and neck/shoulder-discomfort during visually demanding experimental near work

Frequent use of digital information technology has an impact on eye- and neck/shoulder-discomfort. Studies with cross sectional and intervention design indicate an association between the two symptom categories. Still, whether visually demanding near work, per se, contributes to increased neck/shoulder discomfort remains a question of debate. The aim of this laboratory study was to assess if visually demanding experimental near work affects eye- and neck/shoulder-discomfort when the posture was adjusted for comfort and no movements were allowed. Thirty-three healthy subjects performed a visually demanding computer screen task (viewing task) under four different optical lens conditions: binocular -3.5 D and monocular -3.5 D, +3.5 D and ± 0 D. During the experiment subjects were seated in an office chair (with neck support) that was individually adjusted for comfort. At baseline and after each viewing task, subjects reported their perceived eye- and neck/shoulder discomfort on Borg's CR-10 scale. Results show a significant increase of eye discomfort between baseline and the first viewing task, and a significant increase in neck/shoulder discomfort from baseline throughout the first three viewing tasks. Further analysis is required to determent whether the neck/shoulder discomfort was induced by the demanding near work or the static posture, or a combination.     

Exposure assessment in different occupational groups at a hospital using Quick Exposure Check (QEC) - a pilot study

In order to test the feasibility and sensitivity of the ergonomic exposure assessment tool Quick Exposure Check (QEC), a pilot-study was conducted. The aim was to test QEC in different occupational groups to compare the exposure in the most common work task with the exposure in the work task perceived as the most strenuous for the neck/shoulder region, and to test intra-observer reliability. One experienced ergonomist observed 23 workers. The mean observation time was 45 minutes, waiting time and time for complementary questions included. The exposure scores varied between the different occupational groups as well as between workers within the occupational groups. Eighteen workers rated their most common work task as also being the most strenuous for the neck/shoulder region. For the remaining five workers, the mean exposure score were higher both for the neck and shoulder/arm in the most common work task. Intra-observer reliability shows agreement in 86% of the exposure interactions in the neck and in 71% in the shoulder/arm. QEC seems to fulfill the expectations of being a quick, sensible and practical exposure assessment tool that covers physical risk factors in the neck, upper extremities and low back.     

Evaluation of an upper extremity student-role functioning scale using item response theory

Millions of workers suffer from upper extremity (musculoskeletal) disorders. Many of these workers are predisposed to upper extremity musculoskeletal disorders because of early exposure to ergonomic risks as students. Computer usage for four or more hours remains the greatest risk for upper extremity musculoskeletal disorders for workers and students alike. Developing preventative methods to reduce student exposure, and thus protect future workers from upper extremity musculoskeletal disorders later in life, requires an appropriate measure for upper extremity musculoskeletal disorder prevalence and related limitations for student functioning. Item response theory analysis was used to evaluate and further develop a upper extremity functioning scale for the student role.     

Relationship between construction workers' musculoskeletal disorders and occupational health service activities

Construction work consists of numerous factors that influence workers' occupational health and that load the musculoskeletal system in particular. Musculoskeletal disorders are responsible for over a third of all sick leaves lasting over nine days in the construction industry. Occupational health services (OHS) were organized for 85% of the construction workers in our study. The proportion of construction workers who had suffered from chronic or repetitive neck and shoulder, shoulder or arm, or low-back disorders was 55.6%, 44.8% and 42.1%, respectively. Those who felt that they had received enough information, advice or guidance from OHS concerning work posture, work performance or work tools were more often those who had not suffered from shoulder or arm disorders (60.9% vs. 39.1%, p=.024, respectively) or low-back disorders (63.6% vs. 36.4%, p=.034, respectively) during the last month than those who had. Those who had received enough support from OHS concerning maintenance of work ability were more often workers who had not suffered from low-back disorders during the last month than those who had (63.3% vs. 36.7%, p=.004, respectively). OHS should focus more on workers who would really benefit from their activities at a particular time and in a particular situation (primary, secondary or tertiary prevention) and who are themselves devoted to improving their health.     

From usability requirement to technical specifications for hand-held tools and materials: an applied research in the construction field

Literature shows incidence of musculoskeletal disorders in bricklaying workers as well as the relevance of good designed hand-held tools in musculoskeletal disorders prevention. In this framework, it can be supposed that providing usable hand-held tools and material in construction worksites will help to improve bricklayers' working conditions. Here a study is presented aimed at framing a methodology for usability assessment of bricklayers handled objects, in order to provide employers with practical indicators for choosing tools and materials best fitting workers needs, under the effectiveness, efficiency and satisfaction perspective. On the basis of a task analysis, usability requirements for bricklaying hand-held tools and materials have been detailed and related, quantitative and qualitative, technical specifications have been elicited. Theoretical framework and usability assessment methodology are presented and, finally, findings from a field application are discussed.