Year : 2022  |  Volume : 26  |  Issue : 3  |  Page : 135--139

Occupational ergonomics: A special domain for the benefit of workers' health

Somnath Gangopadhyay 
 Department of Physiology, Occupational Ergonomics Laboratory, University College of Science and Technology, University of Calcutta, Kolkata, West Bengal, India

Correspondence Address:
Prof. Somnath Gangopadhyay
Department of Physiology, Occupational Ergonomics Laboratory, University College of Science and Technology, University of Calcutta, 92, A. P. C Road, Kolkata - 700 009, West Bengal

How to cite this article:
Gangopadhyay S. Occupational ergonomics: A special domain for the benefit of workers' health.Indian J Occup Environ Med 2022;26:135-139

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Gangopadhyay S. Occupational ergonomics: A special domain for the benefit of workers' health. Indian J Occup Environ Med [serial online] 2022 [cited 2022 Dec 7 ];26:135-139
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Full Text

Occupational ergonomics is a definite and unique domain of ergonomics that deals with the occupational health of workers in various working fields. It has a prominent impact on the society and socioeconomic status of workers. In another sense, the socioeconomic status of workers will solely rely on their health and productivity. A better workstation improves the health status of workers. But implementation of the same is a big question for economically poor countries. Unfortunately, in India, statistics on occupational diseases and injuries are not maintained regularly. Leigh et al.[1] reported that the incidence of occupational diseases in India is 9,24,700–19,02,300 annually and the number of deaths is 1,21,000. It is further found that major occupational diseases in India are silicosis, musculoskeletal injuries, coal workers' pneumoconiosis, chronic obstructive lung diseases, asbestosis, byssinosis, pesticide poisoning, and noise-induced hearing loss.[2] A relatable picture has emerged from other developing countries as well. Moreover, in developing countries like India, a substantial number of workers, more than 50% of the total working population, are directly engaged in the informal sectors. During work, this population is compelled to violate the natural laws of work. They are bound to perform in a low-wage condition with the maximum amount of physical effort and minimum amount of safety. These findings have opened the door for more research on occupational health and ergonomics in the quest for health protection of vulnerable workers.[3]

Occupational ergonomics is a multidisciplinary perspective for promoting safety and health through effective work design. In modern times, ergonomists collaborate with other occupational health professionals to design jobs that fulfill the three most important qualities of humans: capabilities, limitations, and requirements. The objective of occupational ergonomics is to build a safe and healthy environment for workers which, in turn, will enhance productivity.

There are three major ways of occupational ergonomics: physical, cognitive, and organizational. Through these ways, this distinctive domain contributes not only to organizational success, but also to worker satisfaction and security.

In the last century, occupational ergonomics has become an inevitable part of industrial safety and health. In several ways, the subject is trying to attain the goal: health and safety for all.

There are five aspects of occupational ergonomics: safety, comfort, ease of use, productivity/performance, and esthetics. Occupational ergonomics is a science concerned with the “fit” between people and their work.

Based on the Occupational Safety and Health Administration (OSHA) definition, occupational ergonomics can be simply the study of work. More specifically, ergonomics is the science of designing the task to fit the worker, rather than physically forcing the worker's body to fit the job.

Occupational ergonomics follows the 10 basic principles as follows:

1. Work in a neutral position. 2. Decrease the need for excessive force. 3. Keep materials within easy reach. 4. Work at the proper height. 5. Reduce unnecessary motions. 6. Minimize fatigue caused by the static load. 7. Minimize contact stress. 8. Leave adequate clearance. 9. Move and stretch throughout the day. 10. Keep your environment comfortable.

We have tried our best to address some of these vital issues through physical and cognitive ways for the betterment of workers' health.

 Physical Ways

Handloom weavers and repetitive strain injuries

Handloom is one of the oldest cottage industries in India, particularly in West Bengal, where a considerable number of rural people are involved in weaving. In 2003, a study was performed on handloom weavers. The purposes of that investigation were to elucidate the prevalence of repetitive strain injuries in upper extremities among the handloom weavers and to ascertain the risk factors leading to their development. Statistical analyses revealed a highly significant correlation between the intensity of pain and repetitiveness on one hand and the year of experience as a weaver on the other. By contrast, no significant relationship was found between the chronological ages of weavers and the pain intensity. These reports suggested that highly repetitive work engaged for a long duration could intensify the pain felt and would lead to repetitive strain injuries.[4]

Cumulative trauma disorders among workers

In another study on cumulative trauma disorders (CTDs), it was observed that these disorders commonly occur among workers who need to perform highly repetitive tasks involving continuous hand exertion, vibration, and localized mechanical pressure. In the investigation, an attempt was made to calculate the prevalence of CTD among employees associated with strenuous hand-intensive jobs in unorganized sectors in India and to emphasize the unsafe working conditions to which these workers have been exposed for a number of years. For this reason, an experiment was conducted on 25 male workers from each group. The groups were classified into meat cutters, typists, tailors, visual display terminal (VDT) operators, and weavers. For the survey of symptoms, questionnaire and checklist methods were carried through. Along with these, a detailed time study was performed among the workers during diverse activities in the total work cycle. For this study, a two-tailed Chi-square test of independence was applied to establish whether or not the feeling of discomfort had any significant association with the repetitiveness of the work. From the observations and analysis of the results, it was found that all the task-related activities were repetitive, that is, over 50% of the work cycle of each activity involved the respective main activity where similar kinds of motion patterns were performed. Therefore, it can be concluded that high repetitiveness, work activity for a long duration, and maintaining static posture for a long time may be regarded as the causative factors in the incidents of CTD.[5]

Preadolescent agricultural workers and ergonomics

In India, particularly in West Bengal, preadolescents are primarily associated with agricultural activities in rural areas. Due to poor socioeconomic conditions, they are bound to carry out a considerable number of manual, rigorous tasks in agricultural fields. To investigate the postures adopted by preadolescent agricultural workers during individual agricultural activities and to examine the causes of discomfort related to these postures, a study was conducted. Fifty male and 50 female preadolescent agricultural workers were randomly selected and after performing a detailed posture analysis with the Ovako Working Posture Analysis System (OWAS), it surfaced that the subjects performed their tasks continuously in awkward postures during certain agricultural activities. As a result of these, they suffered from discomfort in different body parts. Although they were very young, they were likely to endure serious musculoskeletal disorders (MSDs) in the future.[6]

Work-related MSDs among sand core workers

A study on sand core making reported that core-making workers often work in uncomfortable postures and suffer from MSDs, primarily affecting the low-back area. Herein, an effort was made to systematize the sand core-making operation for enhancing productivity. The existing process of both types of sand core making involves some unnecessary steps, which hamper the rate of work, and therefore, productivity is hindered. The modified process eliminates these steps and the overall productivity in carbon dioxide sand core making and chemical sand core making is augmented by 8.5% and 30%, respectively. This study showed that the exclusion of certain steps and modifications in the existing process led to a remarkable improvement in productivity.[7]

Work-related MSDs among brass metal workers

Brass metal work is one of the oldest cottage industries in West Bengal, India. Workers executing rigorous hand-intensive tasks are likely to suffer from MSDs affecting their upper limbs. The present investigation was intended to establish the frequency of upper limb MSDs among brass metal workers and to recognize the causal factors behind its advancements. In this study, 50 male brass metal workers (experimental group) and 50 male office workers (comparison group) were chosen. For surveying symptoms, a questionnaire on discomfort feelings was distributed. The repetitiveness of work and handgrip strength of both groups were measured. It was revealed that upper limb MSD was a major problem among brass metal workers, which primarily involved the hand, wrist, fingers, and shoulder. Among the workers reporting subjective uneasiness, most of them felt pain, followed by tingling and numbness in their hands. Many complained of swelling, warmth, and tenderness in their wrists. Their activities were highly repetitive, and the handgrip strength of these workers was significantly less than that of the comparison group. Based on these findings, it appears that high repetitiveness, prolonged work activity (10.5 h of work per day with 8.4 h spent on hammering), and decreased handgrip strength may be the factors involved in the onset of upper limb MSDs among brass metal workers in West Bengal, India.[8]

Posture analysis of prawn seed collectors

In India, particularly in Sundarbans of West Bengal, collection of prawn seeds is one of the major earning resources among prawn seed collectors. They are obligated to carry out an extensive amount of hard, manual, painstaking tasks in the river of the Sundarbans area for collecting prawn seeds. They have to adopt some undesirable postures that may lead to the development of MSDs. The main aim of the study was to inspect the prevalent postures adopted by the prawn seed collectors during individual prawn seed collection and to investigate the causation of feeling of discomfort related to these postures. For this study, 21 male and 25 female prawn seed collectors were selected randomly and a detailed posture analysis was performed using the OWAS method. It was found that these workers labored continuously in awkward postures during certain prawn seed collection activities and consequently, they suffered from feeling of discomfort (pain) in various parts of the body.[9]

Manual Material Handling and Ergonomics

It is a well-documented fact that manual material handling (MMH) entails enormous physical labor and associated feeling of discomfort, which consistently culminate in MSDs. However, mental fatigue, in such cases, becomes an uncultivated parameter that needs definite attention during the assessment of the work status of MMH workers. The present study was performed among 75 porters of a central market in Kolkata to discover the degree of physical and mental exhaustion among them. Short Form 12 health status questionnaire followed by another psychosocial questionnaire were distributed to them. The analysis revealed that most of the porters were under severe physical force and exhaustion as they had to carry about 120 kg load alone at a time and such activity was repeated at least 40 times throughout the day. They always endured pain and feeling of discomfort in different body parts, and this interfered with their normal work activities to a great extent. Moreover, absenteeism means no financial return and even a day of rigorous work fetches a meager income. The inability to support the family convincingly even after performing such perilous tasks makes them feel low. Monotony, boredom, fatigue, and mental trauma form an integral part of their daily work schedule.[10]

Postures During MMH

MMH activities require workers to adopt several awkward postures, leading to the development of MSDs. To study the postures adopted by the MMH workers during heavy load handling and the frequency of MSDs among the workers in Calcutta, India, a cross-sectional study with 100 MMH workers was performed. The frequency of MSD was analyzed via the Standardized Nordic Questionnaire. The OWAS questionnaire was used to study working posture. MSD risk factors were predicted using logistic regression. Ninety-five percent of workers complained of MSD in at least one body part in the past 12 months. According to the OWAS results, 83% of the analyzed work postures required immediate corrective measures for worker safety. The most harmful posture was carrying a heavy load overhead. Carrying more than 120 kg amplified the odds of low back and neck pain by 4.527 and 4.555, respectively.[11]

Playing-related MSDs among musicians

MSDs at work are widespread, incurring substantial costs and hampering the quality of life. They prevail in all occupations, including musicians. Among the musicians, the percussionists are prone to playing-related MSDs (PRMDs). In India, the most popularly used percussion instrument in classical music is tabla. Therefore, the present study was carried out to find the most affected areas of discomfort and to recognize the major risk factors contributing to playing-related musculoskeletal discomforts among Indian tabla players. Eighty-four professional tabla players voluntarily participated in this research study. The Nordic musculoskeletal questionnaire (NMQ) was administered to identify the affected anatomical areas. A questionnaire consisting of eight items rated on a 10-point Likert scale was administered to identify the risk factors contributing to PRMDs. Results of the NMQ showed that the most frequently affected areas were the lower back (74.15%), right shoulder (67.06%), and neck (67.06%). The internal consistency of the questionnaire was determined by Cronbach's alpha, which was found to be acceptable. From the factor analysis results, two factors came up. Factor 1 was identified as posture-related risk factors, while factor 2 was identified as occupation-related risk factors. The risk factors mentioned in the study were similar when compared to other instrumentalists.[12]

Chikan embroidery workers and low back pain

Chikan embroidery is one of the most ancient handicrafts in Indian villages, performed by women artisans being seated in a static position. A study was performed to assess the prevalence of low back pain among chikan embroidery workers. Prevalence of low back pain (87.0%) was observed after analyzing the Nordic questionnaire and the Oswestry low back pain disability questionnaire. Significant associations were established between low back pain and workers' views of rigidity in work methods (odds ratio [OR] 8.3, 95% confidence interval [CI] 2.9–22.7), prolonged working time (OR 6.2, 95% CI 2.3–16.9), dissatisfaction regarding earning (OR 3.3, 95% CI 1.3–8.8), monotonous job pattern (OR 6.6, 95% CI 2.3–8.5), and static sitting posture (OR 4.2, 95% CI 1.6–11.2). Rapid Upper Limb Assessment (RULA) analysis revealed that the working posture is erroneous and necessary rectifications are required soon.[13]

An Intervention Study to Reduce Work-Related MSDs Among Preadolescent Farmers

This study aimed to implement a new ergonomics aid for the betterment of job procedures, increase in productivity, and improve the health and safety of preadolescent farmers. One hundred male and 100 female preadolescent farmers were randomly selected from the villages of Tarakeswar, West Bengal, India, to assess and reduce work-related MSDs and physiological stress. Modified Nordic questionnaires, Body Part Discomfort (BPD) scale, and handgrip strength were evaluated before and after using the ergonomics aid. The results of the study showed that there was a significant change (reduction) in discomfort in the lower back, wrists, shoulder, and hands among preadolescent farmers when using the newly designed ergonomic aid. Handgrip strength improved and physiological stress decreased among preadolescent farmers postintervention than preintervention in just after completion of work conditions. Productivity has been increased in farming by reducing absenteeism from work with the use of ergonomic aid. This study concludes that productivity has been augmented in farming by decreasing absenteeism from work, and that by using the ergonomic aid, the feeling of discomfort has declined markedly.[14]

 Cognitive Ways

Visual and mental fatigue and mental alertness level among smartphone users

According to multiple studies, the use of smartphones leads to several lethal implications such as visual fatigue, mental fatigue, and altered mental alertness level. The purpose of this study was to determine whether there is any instance of visual fatigue, mental fatigue, and changes in alertness. A light meter was used to identify the level of illumination of the experimental room. The critical flicker fusion frequency (CFFF) test was used to find the incidents of visual fatigue, mental fatigue, and changes in alertness. The Student's t-test was performed to investigate the differences in the CFFFs of pre- and post-experimental conditions in both illuminated and dark situations. A decline in post-task CFFF occurred after the completion of the task in both cases. There were significant differences in means between pre- and post-experimental conditions in both illuminated and dark conditions. Post-task mean CFFF values in the dark condition were lesser than in the illuminated condition. It can be recommended from the present study that the use of the smartphone with video features for 30 min or more can source visual fatigue, mental fatigue, and reduced mental alertness among young (22±2.1 years) smartphone users. The use of smartphones in the presence of illumination causes less deleterious effects than in dark conditions.[15]

Perceived usability of products

The use and the production of sanitizers have increased in the post-pandemic situation to prevent the further spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Usability evaluation of sanitizer containers is essentially required to estimate the efficiency, effectiveness, and satisfactory use of the sanitizer containers. This study aimed to assess the system usability scale (SUS) as a marker of perceived usability of non-human computer interfaces (non-HCI) like sanitizer containers. The perceived usability of three types of sanitizer containers was evaluated using SUS. The reliability, convergent, and discriminant validity were measured to evaluate SUS as a marker of usability of sanitizer containers. Results showed that SUS lacks convergent validity, though it has a satisfactory reliability coefficient. Thus, this is not the best measure of usability for non-HCI like sanitizer containers. The SUS had been applied on the flip cap, finger-pressure pump, and spray-type sanitizer containers. The finger-pressure pump container gave higher SUS score than others. The results of this study have shed light on the usability of three different kinds of sanitizer containers. This research provides an overview of the application of SUS on non-HCI like sanitizer containers. This study also suffered from limitations like a lack of convergent validity and lack of ideas to overcome common method bias.[16]

User-experience design and ergonomics

User-experience (UX) design is the process of inclusion of user behavior and user perspective in a product. The process will proceed through usability, accessibility, and desirability of users with a product. Intensification of the interaction with a product is the outcome of UX design. Understanding the connection between end users and the product from the perspective of the system is simplified by citing the following experiment that was performed in the Ergonomics Laboratory at the University of Calcutta. The cooking spatula is one of the main utensils used in the kitchen. In using this spatula, users are experiencing lots of difficulties such as bending and twisting the wrist and repetitive movements. These may generate wrist discomfort and lead to carpal tunnel syndrome. This cooking spatula has no bent angle (0°) and it has a straight handle, and hence, this design leads to wrist bending postures of the users. The existing cooking spatula has less accessibility and desirability during cooking. Three different bent-handled spatulas (0.2 m × 20°, 0.2 m × 15°, 0.2 m × 25°) with handgrip (35°, 45° angle) were designed and given to the users for evaluation. From their responses, a final design (0.2 m, 20° bent angle, and 35° handgrip angle) was selected for further studies. The betterment of the wrist posture of the users was identified by the Rapid Entire Body Assessment and Individual Risk Assessment methods.

The cognitive walkthrough (CWT) method was used for the assessment of the user's cognitive ability about this new design. After using four cognitive questions, it was found that the performances of the users during the usage of the designed cooking spatula were improved. Through the CWT study, system perspective and user experiences about this new design were identified. Kansei Questionnaire was used for the exploration of psychological feelings about the straight-handled spatula and the designed spatula. Kansei Engineering method also recognized the problem faced by the users with the existing spatula (0° bent angle) and those problems were rectified in this new design. The questions with Kansei terms were plotted in a line diagram and it showed that the users had less wrist bending, twisting, and least strength on their wrist while using the designed cooking spatula.[17]


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