Postural Loading Assessment in Assembly Workers of an Iranian Telecommunication Manufacturing Company

A novel risk assessment model for work-related musculoskeletal disorders in tea harvesting workers

Work-related musculoskeletal disorders (WMSDs) are the most common occupational health problems in agriculture workers due to repetitive and excessive force movement activities involved in their job processes. The Fine-Kinney method has been commonly used as a quantitative evaluation method in risk assessment studies. Classically, the risk value via Fine–Kinney is calculated by the mathematical multiplication irrespective of the degree of importance of each risk parameter (probability (P), exposure (E), and consequence (C)). Hence, a novel risk management model was proposed based on integrating Fine-Kinney and spherical fuzzy AHP-TOPSIS. First, each risk parameter is weighted using the spherical fuzzy AHP (SF-AHP). Second, the spherical fuzzy TOPSIS (SF-TOPSIS) method is used for hazard ranking. The proposed model is applied to evaluate risks in tea harvesting workers for work-related musculoskeletal disorders. Subsequently, a sensitivity analysis is carried out to test the proposed model. Finally, we compare the proposed model’s applicability and effectiveness with the spherical fuzzy COmbinative Distance-based ASsessment (SF-CODAS) method based on Fine-Kinney. The ranking similarity between the proposed Fine-Kinney-based SF-TOPSIS and SF-CODAS methods is checked by applying Spearman’s rank correlation coefficient, in which 92% of rankings are matched.

Evaluation of musculoskeletal workload of manual operating tasks using a hydraulic jack based on ergonomic postural analysis and electromyography: A case study of non-professional young male users

BACKGROUND:

Manual operations of the hydraulic jack device can become ergonomic stressors for the musculoskeletal system because of the required operational forces, muscle activities, or working postures. However, the usability of the hydraulic jack has not been fully explored for non-professional personnel.

OBJECTIVES:

To evaluate the musculoskeletal loads during manual operations of a hydraulic jack based on the ergonomic postural analysis and electromyography

METHODS:

Nine men operated the lever of a hydraulic jack with three positions: parallel to and near (P-N), parallel to and far from (P-F), and orthogonal to the jack lever (O). Postural loads were evaluated by Loading on the Upper Body Assessment (LUBA), an ergonomic observational method, and were classified into action categories. The surface electromyogram of eight muscles and the subjective sense of burden were also measured.

RESULTS:

The initial force for lever pushing reached 40–80 N and exceeded the recommended forces for the unusual postures. The overall assessment of LUBA showed that 31% of working postures observed in O position require immediate consideration and corrective action and the maximum holding time estimated was < 1 minute. The postural load increased due to the shoulder joint abduction in the P-F and O positions and due to the trunk rotation in O position.

CONCLUSIONS:

The results suggest that operating the hydraulic jack cause considerable postural loads and manual forces insufficient for several minutes of manual task. Therefore, improving working methods and tool designs are needed to improve usability and decrease the risk of musculoskeletal disorders during jack operations.

Common errors in selecting and implementing pen-paper observational methods by Iranian practitioners for assessing work-related musculoskeletal disorders risk: a systematic review

Objectives. This study aimed to determine the types and frequency of pen-paper observational methods (OMs) used by Iranian practitioners and to identify their errors in selecting and implementing these methods. Methods. This was a systematic review and analytical study of papers in which the OMs had been used. Scientific databases were analyzed from September 1970 to September 2018. Errors were determined based on a list of wrong practices both in the selection and implementation of methods. Three ergonomists carried out the process of identifying errors independently. Results. The most frequently used methods were rapid upper limb assessment (RULA), quick exposure check (QEC) and rapid entire body assessment (REBA), respectively. Errors in selecting and implementing pen-paper OMs were 53.3 and 36.4%, respectively. Conclusions. Despite the abundant number of pen-paper OMs, Iranian practitioners use few of them. The high rate of errors can indicate a lack of knowledge and skills among practitioners for selecting and implementing OMs. The development of decision-making tools may help practitioners to select appropriate pen-paper OMs for assessing different types of tasks.

Low cost ergonomic interventions to reduce risk factors for work related musculoskeletal disorders during dairy farming

BACKGROUND

Workers engaged in dairy farming are exposed to awkward and poor postures that may result in work-related musculoskeletal disorders (WMSDs).

OBJECTIVE

This study carried out ergonomic interventions in order to eliminate and reduce awkward postures in dairy farming.

METHODS

This quasi-experimental study applied rapid entire body assessments (REBA) to evaluate the risks associated with each posture while performing the assigned tasks on a dairy farm in Iran to identify high and very high-risk tasks. A participatory ergonomics model was used that incorporated suggestions by dairy workers to design the used interventions.

RESULTS

In the first intervention, by using an automatic transmission system for pouring milk, one high and one very high-risk task- pouring milk into a bucket and pouring milk from a bucket into a tank, respectively- were eliminated. In the second intervention, two high-risk tasks- filling corn containers and pouring corn into the milling machine- were eliminated by using a material conveying vacuum pump to transfer corn from the ground to the opening of the milling machine. In the third intervention, a simple and cheap holding device for the bag was designed to reduce the posture risk score from very high to medium. The fourth intervention involved the use of a shovel with a handle appropriate to the anthropometric characteristics of the workers that reduced the posture risk from very high to medium.

CONCLUSIONS

The results indicated that applying participatory ergonomic principles along with low cost and simple designs with high performance resulted in significant reductions in postural risks pertaining to of musculoskeletal disorders on Iran dairy farms.