Occupational Repetitive Actions Research Articles

Job rotations based on physical and psychological workloads: A proposal for the footwear industry

IntroductionThe aim of this study is to propose a model of job rotations in shoes (sandals and tennis shoes) production cells, aiming at reducing the risk exposure to work-related musculoskeletal disorders considering physical and psychological workloads. MethodsThe physical load was assessed by the Occupational Repetitive Actions method, and the psychological load by the Job Stress Scale. A total of 259 workers in the footwear industry participated in this study. These loads were incorporated into a multi-objective mathematical programming model, where the objective functions aimed to minimize the maximum work-related musculoskeletal disorders and the maximum total work demand, and to maximize the minimum work control and social support to which a worker might be exposed during a daily journey. To the best of our knowledge, this is the first time in the literature that physical and psychological aspects are considered when solving job rotation problems. To tackle the problem, we propose a matheuristic based on an epsilon-constraint framework. This method allows us to generate different solutions with respect to the specific objective functions. To assess the effectiveness of the solutions, we calculated the variance of the scores of the physical and psychological loads in the conditions without and with rotations. ResultsFive rotation solutions were reached for the sandal production cells and twelve for the tennis shoe production cells. There was a reduction in the variation of physical and psychological loads in all solutions for both cells when compared to the no rotation condition. However, for the sandal production cells, the reduction in variation between the physical loads of the conditions with and without rotations was not significant due to the similarity of the exposure indices. ConclusionsThe model reduces the risk of work-related musculoskeletal disorders, promoting variability in muscle recruitment and enrichment of work content, being applicable in other segments.

A Twenty-Year Retrospective Analysis of Risk Assessment of Biomechanical Overload of the Upper Limbs in Multiple Occupational Settings: Comparison of Different Ergonomic Methods.

Several methods with which to assess the risk of biomechanical overload of the upper limb are described in the literature. We retrospectively analysed the results of the risk assessment of the biomechanical overload of the upper limb in multiple settings by comparing the application of the Washington State Standard, the threshold limit values (TLV) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH), based on hand-activity levels (HAL) and normalised peak force (PF), the Occupational Repetitive Actions (OCRA) checklist, the Rapid Upper-Limb Assessment (RULA), and the Strain Index and Outil de Repérage et d'Evaluation des Gestes of INRS (Institut National de Recherche et de Sécurité). Overall, 771 workstations were analysed for a total of 2509 risk assessments. The absence of risk demonstrated for the Washington CZCL, used as the screening method, was in good agreement with the other methods, with the sole exception of the OCRA CL, which showed at-risk conditions in a higher percentage of workstations. Differences in the assessment of the frequency of actions were observed among the methods, while their assessments of strength appeared to be more uniform. However, the greatest discrepancies were observed in the assessment of posture. The use of multiple assessment methods ensures a more adequate analysis of biomechanical risk, allowing researchers to investigate the factors and segments in which different methods show different specificities.

Occupational ergonomic assessment of MSDs among the artisans working in the Bagh hand block printing industry in Madhya Pradesh, India

Objectives. The hand block printing technique practiced in Dhar District of Madhya Pradesh involves highly repetitive tasks with awkward posture, which contribute to the development of musculoskeletal disorders (MSDs) among the artisans, The aim of this study was to determine the prevalence of MSDs and the risks factors involved. Methods. An observational study and a self-reported questionnaire study were conducted with a sample of 70 artisans. The working postures of the artisans were analyzed using rapid upper limb assessment (RULA) and the occupational repetitive actions (OCRA) method. p ≤ 0.05 was considered significant throughout the study. Results. MSDs in the neck, shoulders, elbows, wrist/forearm, lower back and hips/thighs were found to be highly prevalent among artisans of age greater than 31 years and experience greater than 11 years. Most complaints were reported in the wrist, neck and lower back region. Conclusion. From the findings, it was evident that artisans working in Bagh printing are at high risk of the development of MSDs; thus, an immediate intervention is needed to eliminate the ergonomic risks among the artisans.

Agreement between observed and interview-based exposure to ergonomics factors for the upper extremities in employees of a package sorting plant

Aim of the study was to estimate agreement between observational and interview-based exposure to ergonomic factors at work. Thirty-two male workers employed in a logistics hub were interviewed through the OCRA check-list on exposure to ergonomic factors in one of six work tasks. Observations of workers in each work task, based on the same OCRA check-list, were used to assess exposure in that task. Agreement between observed and interview-based scores of the check-list OCRA index, as well as of frequency and posture, was estimated both at individual and task group level through the Intraclass Correlation Coefficient (ICC). At work task level, high concordance was found between observed and interview-based scores for all the exposures examined, while at the individual level agreement was moderate. These results suggest that exposure assessment through interviews based on the OCRA check-list is a valid method, which could be used as a workstation screening tool. Practitioner summary: The study aimed to evaluate agreement between observational and interview-based exposure to ergonomic factors at work, assessed through the OCRA check-list on 32 male workers. Agreement was found at least moderate, suggesting that interview-based exposure assessed through the OCRA check-list could be used as a proxy of observations for workstation screening. Abbreviations: ART: assessment of repetitive tasks; CI: confidence intervals; EAWS: European assembly worksheet; ICC: intraclass correlation coefficient; ISO: International Standards Organization; OCRA: occupational repetitive actions; ULRA: upper limb risk assessment; WUEMSDs: work-related upper extremity musculoskeletal disorders

Effects of OCRA parameters and learning rate on machine scheduling

In this paper, the effects of Occupational Repetitive Actions (OCRA) parameters, learning rate on process times, and machine scheduling were investigated. We propose that Work-Related Musculoskeletal Disorder (WMSD) risks should be taken into account in machine scheduling. To the best of our knowledge, none of the earlier methods simultaneously considered effects of WMSD risks and the learning rate on processing times. The OCRA index method was employed for WMSD risk assessments. In this context, OCRA parameters such as duration, recovery, force, posture, and repetitiveness were analyzed. Observed process times of each factor were obtained from video records. Statistical analysis (ANOVA) revealed a positive (r=0.616) relationship on processing times with OCRA indexes in independent t-tests at significance level 0.05. To investigate the effects of WMSD risk, our Scheduling with Learning Effect under Risk Deterioration (SLE&RD) model was compared with six existing machine scheduling models in the literature. Detailed machine scheduling instances of 9 jobs with WMSD risks revealed that job sequences and makespan varied under different scenarios. This means that WMSD risks and OCRA factors affect machine scheduling with a deterioration effect. The results confirmed that when WMSD risks are included, actual process time and makespan move closer to observed process times. To obtain more accurate machine scheduling, which is close to real-life applications, WMSD risks, and learning rates should be considered simultaneously. The SLE&RD model is promising in machine scheduling for real-life problems and presents a holistic view of machine scheduling and WMSD risks.

Occupational Risk Evaluation Through Infrared Thermography: Development and Proposal of a Rapid Screening Tool for Risk Assessment Arising from Repetitive Actions of the Upper Limbs.

Risk analysis is one of the main tools for preventing the occurrence of Work-Related Musculoskeletal Disorders. New methods of risk analysis should seek to be more agile and simplified, encouraging them to be widely applied in work environments. This paper aimed to develop a rapid tool for assessing the risk of developing Work-Related Musculoskeletal Disorders (WMSDs) arising from repetitive actions of the upper limbs, while using a thermographic camera to measure skin temperature variation. A workstation was developed in an environmentally controlled laboratory, representing the five levels of risk presented by the Occupational Repetitive Actions Index (OCRA) Index, which were performed by 32 participants for 20 min. each level. There was a significant change in forearm skin temperature at all risk levels (p < 0.001), with a positive linear correlation (r = 0.658 and p < 0.001), which led the authors to perform linear regression analysis for the forearm region. The Predicted OCRA Index calculation equation was successfully developed (R = 0.767 and R² = 0.588), while using as independent variables: air temperature and temperature variation of the forearm skin. The Predicted OCRA Index can be applied as a screening tool for large numbers of workers in the same company or sector, due to its speed of application and the determination of risk level, but it does not replace the original OCRA Index.

Parallel Machine Scheduling with WMSD Risk Considerations

This paper introduces the parallel machine scheduling problems with work related musculoskeletal disorder (WMSD) risk considerations. By the WMSD consideration, we mean that job processing times are an increasing function of occupational repetitive technical actions (OCRA) risk factor. The OCRA index was recruited for risk assessment of occupational repetitive technical actions. WMSD risks were modeled with cumulative mean value of OCRA index. Due to NP-Hard structure of parallel machine scheduling problems with WMSD considerations and learning rate, the solution cannot be found always. However, problem can be solved by transforming assignment problem. In spite of the fact that the computational effort remains O (n 4 ), problem is solved within more efficient time. In this study, a model that includes learning effect and WMSD risk was proposed. WMSD risk was considered as cumulative mean of risk value throughout shift. In order to the balance between productivity and WMSD risk, jobs’ foreseeable cycle time (FCT) value was changed. It is aimed to decrease mean of risk along schedule without increasing total basic process time. The value of sacrifice from the FCT was compensating from job which have optimal, acceptable, borderline or slight risk level. Process time and risk values were recalculated by using new FCT value. Thus, balanced process times and risk values obtained. Proposed model was solved with Lingo software and sequence of jobs was obtained. Total flow time and mean of risk were compared for balanced and none balanced schedules. Total flow time and mean of risk belong to balanced schedule is smaller than none balanced schedule. It was shown that handled problem is solvable at the polynomial time and total flow time can be improved by bringing balance between WMSD risks and productivity.

PROGRAMACIÓN DE LA PRODUCCIÓN EN ENTORNOS REPETITIVOS CON RESTRICCIONES ERGONÓMICAS

In the manufacturing industry it is common to find work activities where workers are subjected to excessively repetitive movements, being this one of the risk factors most commonly linked to musculoskeletal disorders (MSD). Lack of "recovery periods" increases muscle fatigue and therefore increases the likelihood of workers suffering from MSD (Colombini et al. 2002). Various ergonomic assessment methods are currently used to determine the level of risk to which workers are exposed when performing repetitive movements. In this proposal, the OCRA (Occupational Repetitive Actions) method has been chosen (Colombini et al., 2002). The OCRA method is included in the UNE-EN 1005-5:2007 and ISO 11228-3:2007 standards.

Assessment of exposure packaging worker and designing work methods using OCRA index in fertilizer producer company

Repetitive tasks carried out by packaging workers of fertilizer producer company. These task led to some complains of pain and fatigue on upper body part of the workers based on Nordic Body Maps (NBM) questionnaire. This is because the workers work continuously for eight hours per shift and no recovery period. This study aims to determine risk level of musculoskeletal disorders and break time calculation. In this study, using Occupational Repetitive Actions (OCRA) index to reduce the risk level. The samples according to expert judgement criteria are three workers (packer clamper, packer tailor and loader). The improvement in this study is designing work methods with break time calculation. This improvement shows the risk reduction on the left hand of the packer clamper from 4,2 to 3,4 and the right hand from 9,9 to 8,2. Risk reduction on the left hand of the packer tailor from 3,44 to 2,2 and the right hand from 5,7 to 2,26 while the risk level on the left hand of loader from 1,4 to 0,87 and in the right hand from 2,17 to 1,18.

Beyond OCRA: Predictive UL-WMSD risk assessment for safe assembly design

In terms of occupational safety, one of the most important areas to consider is that of Upper-Limb Work-related MusculoSkeletal Disorders (UL-WMSDs), i.e. work-related disorders due to biomechanical overload of the upper limbs caused by protracted movements and/or repeated efforts throughout the workday. To estimate the risk associated with these disorders, the method known as the OCRA (OCcupational Repetitive Actions) Index is universally accepted; based on observation, it provides an index whose value is related to the expected percentage of pathological cases among the entire working population. This work introduces a different perspective to the problem in order to provide designers with a method – PRASAD: Predictive Risk Assessment for Safe Assembly Design – that makes them aware of the issues related to UL-WMSDs, starting from the earliest stages of the design of a new product and the related assembly workstation, well earlier than observing the activities associated to its production, that is when the assembly workstation is fully set and running. The main advantage of the method lies in the outcome, the PRASAD Index, which is fully comparable with the OCRA Index, so that the proposal leverages on the well-known OCRA standard approach. The new method, aimed at a use in the design phase (of a new workstation for a new product), is potentially useful for a conventional risk assessment of existing workstations as well: it combines the rapidity of a checklist for the initial screening with a level of detail that is characteristic of advanced methods, such as the OCRA Index. Finally, PRASAD represents an innovation in the risk assessment of UL-WMSDs because of its feature of modelling the concept of “Technical Actions”, which enables estimating (and taking into account) the repetitiveness of tasks, based on technical design and production management data.

Risk assessment of cheese processing tasks using the Strain Index and OCRA Checklist

The purpose of this study was to conduct and compare two ergonomic risk assessment methods often used in occupational health research and practice: the Strain Index (SI) and Occupational Repetitive Actions (OCRA) Checklist. Seven raters used the SI and OCRA Checklist to assess task-level physical exposures to the upper extremity of workers performing 21 cheese-manufacturing tasks. Of the total task exposures assessed with both methods, nearly half (49.1%) were classified as hazardous using the OCRA Checklist while 60.2% were classified as hazardous using the SI. Although the underlying injury risk characterization constructs of the SI and OCRA Checklist differ, the results indicated that the SI and OCRA Checklist often classified job tasks into similar risk categories. The differences in risk classifications determined by the SI and OCRA Checklist for job tasks were likely related to the definition of variables measured by these assessment methods as well as the complexity of tasks evaluated. By design, the SI is specific to the distal upper extremity while the OCRA Checklist accounts for the entire upper extremity including the shoulder. When conducting risk assessments of industrial work tasks, the choice of analysis tools should be based on the purpose of the assessment and the complexity of task functions. Both the SI and OCRA Checklist yield risk assessment ratings that are similar for cheese processing tasks.

A Review on Methods for Assessing Risk Factors of the Upper Limb Disorders among Cashiers in Grocery Retail Industries

This paper provides an overview of the various methods that have been developed for the assessment of risk factors for upper limb disorders among cashiers in grocery retail industries. This paper is essential as upper limb disorders have been known as one of the prime cause of work-related disability in various countries. The methods used for the assessment were the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, the Assessment of Repetitive Tasks (ART), the Job Strain Index (JSI) and the Occupational Repetitive Actions (OCRA) Checklist. DASH questionnaire is a structured interview in determining the prevalence of the upper limb disorders, while ART, the JSI and OCRA Checklist act as a direct observation in examining the involvement of risk factors. Basically, these tools dealt with the measurements of symptoms, posture observation, and workplace risk assessment, as they are the most relevant tools for assessing the risk factors faced by the workers in grocery industries. The use of these tools assessed the risk factors and consequently reduces the risk of injuries among the workers.

Risk of WMSDs in monofunctional and multifunctional workers in a Brazilian footwear company

Abstract This study aimed to analyze the risk of musculoskeletal disorders in monofunctional and multifunctional workers in a footwear company. The sample comprised 114 workers in the shoe production sector. The method Occupational Repetitive Actions was used to assess the risk of work-related musculoskeletal disorders (WMSDs). Proportional odds models were constructed, relating the risk of WMSDs to the type of work and the worker’s level of multifunctionality. For monofunctional workers, exposure to the higher risk was related to cycle time and the technical actions within their activities, whereas for multifunctional workers, it was related to the range of motion, use of gloves and precision needed in activities. For monofunctional workers, greater risks were associated with a short activity cycle, whereas for multifunctional workers, they were associated with complementary and organizational factors. Moreover, workers whose intracellular activities were less than 30% of the total appeared to be less exposed to the risk of WMSDs.

Analytical characterization of movements of the spinal column and risk assessment due to repeated movements of the upper limbs of building painters

Manual activities of construction workers may induce musculoskeletal disorders. This study on a group of painters aimed to analytically characterize movements of the spinal column by both lumbar motion monitor and television cameras and to determine, using the Occupational Repetitive Actions (OCRA) Index method, the risk exerted by repeated movements of the upper limbs. The main results are: painting with a roller generally exposes workers to a lesser risk for upper limbs than painting with a brush; a roller-stick fixed at the wrong length can lead to stretching of the back at lumbar and cervical levels; to remain within the range of ‘acceptable risk’ (OCRA Index evaluation), a worker should not paint a vertical wall for over 3 h if using a roller and 2.5 h if painting with a brush; and, on average, a painter who paints for 5 h in a day lifts the bucket about 120,140 times.

How to Assess the Biomechanical Risk Levels in Beekeeping

ABSTRACTBeekeepers are at particular risk of developing work-related musculoskeletal disorders, but many of the studies lack detailed exposure assessment. To evaluate the biomechanical overload exposure in a specific farming activity, a multitasking model has been developed through the characterization of 37 basic operational tasks typical of the beekeeping activity. The Occupational Repetitive Actions (OCRA) Checklist and the National Institute for Occupational Safety and Health (NIOSH) Lifting Index methodologies have been applied to these elementary tasks to evaluate the exposure, and the resulting risk indices have been time-weighted averaged. Finally, an easy access, computer-assisted toolkit has been developed to help the beekeepers in the biomechanical risk assessment process. The risk of biomechanical overload for the upper limbs ranges from acceptable (maintenance and recovery of woody material and honey packaging with dosing machine tasks) to high (distribution of the top supers) risk level. The risk for back injury is always borderline in women and increases with exposure time, whereas it ranges from acceptable to borderline in men. The definition of the biomechanical risk levels allows for planning of corrective actions aimed at preventing and reducing the risk of musculoskeletal disorders through engineering, administrative, and behavioral interventions. The methodology can be used for risk assessment in other mainly manual agricultural activities.

Carpal Tunnel Syndrome and Food Manual Labor: Case Report and Compensation Issues

Aims: We report a case of bilateral carpal tunnel syndrome (CTS) in a patient who had been working with repetitive tasks for almost thirty years on his own business as pizza maker in a small restaurant. Food production outside the industry of food processing is often neglected in assessing biomechanical overload as an occupational risk for upper limb musculoskeletal disorders. Presentation of Case: A 54-year old male reported a progressive history of pain and numbness in the thumb and first three fingers of both hands, including dysaesthesia and nocturnal waking. Main factors influencing the risk such as frequency of repetitive movement, strain, posture, pauses, complementary risk factors are described. On site mini-check list Occupational Repetitive Actions (OCRA) assessed 40/50 technical actions per minute with peak acceleration related to customers’ demand and showed a middle-high risk with score 20. Discussion and Conclusion: Criteria used for determining eligibility for compensation are not uniform and according to regulations of a single country may cover different aspects of physiological impairment, work disability, healthcare costs, loss of income and professional retraining. This case highlights the importance of using more easily applicable tools for risk assessment that can be crucial for definition and determination of causation.

Risk Assessment of Repetitive Movements in Olive Growing: Analysis of Annual Exposure Level Assessment Models with the OCRA Checklist.

In Italy, one of the main agricultural crops is represented by the cultivation of olive trees. Olive cultivation characterizes the Italian agricultural landscape and national agricultural economics. Italy is the world's second largest producer of olive oil. Because olive cultivation requires the largest labor force in southern Italy, the aim of this research was to assess the risk of biomechanical overload of the workers' upper limbs. The objective, therefore, was to determine the level of risk that workers are exposed to in each phase of the production process. In Calabria, the second most important region in Italy for both the production of olive oil and cultivated area, there are 113,907 olive farms (83% of all farms) and 250,000 workers. To evaluate the risk of repetitive movements, all of the work tasks performed by workers on 100 farms in Calabria were analyzed. A total of 430 workers were interviewed over the four-year research period. To evaluate the level of exposure to repetitive movements, the OCRA (occupational repetitive actions) checklist was adopted. This checklist was the primary analytical tool during the preliminary risk assessment and in a given working situation. The analysis suggested by the OCRA checklist starts with pre-assigned scores (increasing in value with intensification of risk) for each of four main risk factors and additional factors. Between 2010 and 2013, surveys were conducted using the OCRA checklist with the aim of verifying musculoskeletal risks. The results obtained from the study of 430 workers allowed us to identify the level of exposure to risk. This analysis was conducted in the workplace to examine in detail the repetitive movements performed by the workers. The research was divided into two phases: first to provide preliminary information on the different tasks performed in olive growing, and second to assign a percentage to each task of the total hours worked in a year. Based on the results, this method could well become a tool for implementing prevention measures for all workers involved in farming, not just those in olive production. Exposure to work-related musculoskeletal risks (extreme posture, repetition, high muscle loads) appears to be significant for workers in olive production. In the cultivation of olive trees, many tasks require prolonged and intense physical efforts that can increase risk. The most problematic work tasks were pruning and harvesting, while fertilization showed the lowest risk. The survey showed the need for a suitable study of olive growing to adapt prevention measures to specific aspects of agriculture as compared to other employment sectors.

Productivity and ergonomic risk in human based production systems: A job-rotation scheduling model

The competitiveness of modern manufacturing systems is based on a high production rate and a high level of flexibility. Despite the high level of automation achieved in production systems, flexibility is often provided by human dexterity and the cognitive capabilities of the workforce, as in assembly lines. In the case of repetitive manual tasks, workers are exposed to the risk of musculoskeletal disorders (MSDs). In these contexts, a high production rate leads to high physical workload, and job rotation is adopted in order to reduce the ergonomic risk. Traditionally, ergonomics and human performance issues have been investigated separately. However, in the design and scheduling of human-based manufacturing systems, a reliable description of human components is required in order to jointly evaluate production system performance and assess workers׳ risk of MSDsIn this paper, the authors propose a model which aims to find optimal job rotation schedules in work environments characterized by low load manual tasks with a high frequency of repetition (e.g. assembly lines). The model is a mixed integer programming model allowing for the maximization of production rate jointly reducing and balancing human workloads and ergonomic risk within acceptable limits. Risk and its acceptability are evaluated using the OCRA (OCcupational Repetitive Actions) method (ISO 11228-3:2007), widely recognized as an effective tool for the risk assessment of Upper Limb Work related MSDs (UL-WMSDs). Moreover, the different workers׳ performance due to their respective training levels and skills is considered in the problem formulation.The model is applied to an industrial case study. Results show the model׳s capacity to identify optimal job rotation schedules jointly achieving productivity and ergonomic risk goals. Performances of the solutions obtained improve as workforce flexibility increases.

The inter-rater reliability of Strain Index and OCRA Checklist task assessments in cheese processing

The purpose of this study was to characterize the inter-rater reliability of two physical exposure assessment methods of the upper extremity, the Strain Index (SI) and Occupational Repetitive Actions (OCRA) Checklist. These methods are commonly used in occupational health studies and by occupational health practitioners. Seven raters used the SI and OCRA Checklist to assess task-level physical exposures to the upper extremity of workers performing 21 cheese manufacturing tasks. Inter-rater reliability was characterized using a single-measure, agreement-based intraclass correlation coefficient (ICC). Inter-rater reliability of SI assessments was moderate to good (ICC = 0.59, 95% CI: 0.45–0.73), a similar finding to prior studies. Inter-rater reliability of OCRA Checklist assessments was excellent (ICC = 0.80, 95% CI: 0.70–0.89). Task complexity had a small, but non-significant, effect on inter-rater reliability SI and OCRA Checklist scores. Both the SI and OCRA Checklist assessments possess adequate inter-rater reliability for the purposes of occupational health research and practice. The OCRA Checklist inter-rater reliability scores were among the highest reported in the literature for semi-quantitative physical exposure assessment tools of the upper extremity. The OCRA Checklist however, required more training time and time to conduct the risk assessments compared to the SI.

Dynamic digital human models for ergonomic analysis based on humanoid robotics techniques

Digital human models can be used for biomechanical risk factors assessment of a workstation and work activity design for which there is no physical equipment that can be tested using actual human postures and forces. Yet, using digital human model software packages is usually complex and time-consuming. A challenging aim therefore consists in developing an easy-to-use digital human model capable of computing dynamic, realistic movements and internal characteristics in quasi-real time, based on a simple description of future work tasks, in order to achieve reliable ergonomics assessments of various work task scenarios. We developed such a dynamic digital human model, which is automatically controlled in force and acceleration and inspired by human motor control and based on robotics and physics simulation. In our simulation framework, the digital human model motion was controlled by real-world Newtonian physical and mechanical laws. We also simulated and assessed experimental insert-fitting activities according to the occupational repetitive actions (OCRA) ergonomic index. Simulation led to satisfactory results: experimental and simulated ergonomics evaluations were consistent, and both joint torques and digital human model movements were realistic and coherent with human-like behaviours and performances.