ERGONOMIC RISK ANALYSIS AND MUSCULOSKELETAL DISORDERS (MSDs) ON OPERATOR UNIFORMITY FINAL INSPECTION
Mariyatul Qibtiyah
Magister of Public Health, Public Health Faculty, Universitas Muhammadiyah Jakarta Jl. K.H. Ahmad Dahlan, Cirendeu, Ciputat, Tangerang Selatan, 15419
Email: [email protected]
ABSTRACT
One of the occupational diseases in the workplace is related to ergonomics, ergonomics factors are very important to prevent work-related diseases and incidents. Disorders arising from inappropriate ergonomics affect the musculoskeletal system, Musculoskeletal disorders (MSDs), namely disorders of body structures such as muscles, joints, tendons, ligaments, nerves, cartilage, bones, and the local blood circulation system. This study aims to analyze the ergonomic risks and MSDs in workers. The population is all uniformity operators totaling 203 employees. The sample that met the inclusion criteria is 93 operators. The ergonomic risk was assessed based on the REBA sheet, and MSDs using the Nordic Body Map. Data were analyzed using the chi-square test. The results showed the level of risk in the booking process is 'high' (score 8); input uniformity is 'medium' (score 6), uniformity output is 'medium' (score 7) and the balancing process is 'medium' (score 6). Uniformity final inspection operators have MSDs are 88 peoples (94.62%) and did not has MSDs are 5 peoples (5.38%). Statistical test results show that there is no relationship between age, years of service, and education on MSDs operator Uniformity Final Inspection. Suggestions for research are providing lifting aids, job training or training on ergonomic risks and safe working procedures according to ergonomic principles, and work in accordance by power zone. providing personal protective equipment such as back support and setting appropriate working time and rest hours.
Keywords: Ergonomic, Musculoskeletal disorders, REBA, Nordic Body Map.
INTRODUCTION
One of the occupational diseases in the work environment is related to ergonomics, ergonomics factors are very important to consider in its management in the work environment so that work-related diseases and work accidents do not occur that can cause losses for employers and workers (Peraturan Presiden RI Nomor 7, 2019). According to the Minister of Manpower Regulation No. 5 of 2018 concerning the work environment, ergonomics factors are factors that can affect labor activities, caused by mismatches between work facilities which include working methods, working positions, working tools, and lifting loads on the workforce (Permenaker, 2018).
According to the International Labor Organization (ILO), the estimated global burden of disease caused by occupational risk factors (2021) in the 2000–2016 report on the burden of work- related illnesses and injuries in the DALY's (Disability-Adjusted Life Years) category was 89.72 million, 12,27 million of it (13.7%) were caused by ergonomic risk factors (International Labour Organization, 2021). Meanwhile, the Health Safety Environment (HSE) in the Work-Related Musculoskeletal Disorders statistics in Great Britain in 2021 stated that there were 470,000 suffering from work-related MSDs. The HSE categorizes based on the effect on the affected body area, data for 2020/2021 76,000 (16%) workers in the UK experienced MSDs in the lower limbs, 182,000 workers (39%) experienced MSDs on the back and 212,000 workers (45 %) had MSDs in the upper limbs or
neck (HSE, 2021). Based on research conducted by Norus Sholeha and Merry Sunaryo (2021) all workers experience MSD symptoms with the body parts experiencing the most pain/pain in the upper neck, back, waist, buttocks, and right calf (Norus&Merry, 2021).
Inconvenience caused by inappropriate ergonomics affects the musculoskeletal system.
Musculoskeletal disorders or skeletal muscle disorders are commonly called musculoskeletal disorders (MSDs). Musculoskeletal disorders (MSDs) are disorders of body structures such as muscles, joints, tendons, ligaments, nerves, cartilage, bones, and the local blood circulation system. If MSDs are caused or exacerbated mainly by the work and by the effects of the immediate environment in which the work is carried out, then it is known as work-related MSDs (EU-OSHA, 2019).
Identification of potential hazards and risks that have been carried out, it is known that operator uniformity final inspection one of the potential risks is the occurrence of MSDs (HIRADC, 2021), this means that efforts to control need to be carried out so that these potential hazards can be minimized so that a safe work process can be created. and there is no occupational disease caused by the ergonomic hazard. One of the efforts made is to know the value of the ergonomic risk that can be measured and the value and potential of activities that have ergonomic hazards can be identified so that they can provide appropriate advice. According to Karwoski (2006), several practical assessment tools are available to measure ergonomics including the NIOSH Lifting Equation, LMM Risk Assessment Model, REBA, RULA, LUBA, The ACGIH TLV, and others where each of these tools, if used properly, each can play a key role as part of a comprehensive ergonomic process (Karwowski, 2006).
The results of the preliminary survey that has been carried out, there are operator complaints about ergonomic factors that are reported to the safety team. The three main symptoms reported by the operator were pain in the shoulder, calf, and arm. The work process in the uniformity final inspection section has an ergonomic hazard, one of the causes is manual handling activities with heavy tires lifted weighing between 12 - 30.9 kg, repetitive work of moving loads from the conveyor or floor to the trolley/racks. To assess MSDS symptoms, you can use the Nordic Body Map (NBM), through NBM workers can identify the part of the muscles and indicate the position of the symptoms (Tarwaka et al., 2004).
To avoid MSDs symptoms caused by inappropriate ergonomic factors, according to Manuba in Tarwaka it is stated there needs to be harmony between workers and their work, so that workers can work following human abilities, capability, and limitations, which are influenced by various factors, such as age, gender, race, anthropometry, health status, nutrition, physical fitness, education, cultural skills, behavior, habits, and adaptability (Tarwaka et al., 2004). According to the International Commission on Occupational Health (ICOH), the elements of workers in the workplace to improve ergonomics are influenced by several characteristics including age, health, residual disability, physical and mental capacity, experience and skills, education, and training (ICOH, 2010).
The purpose of this study was to analyze the risks of ergonomics at work, and MSDs symptoms and determine the relationship of individual factors (age, years of service, and education) to MSDs symptoms.
METHOD
This study is a survey research using a cross-sectional design to collect information from employees who were working in uniformity final inspection. The Population is all operators in the Uniformity Final Inspection process, totaling 203 employees. The sample of this research is workers who meet the inclusion criteria, namely operators who are in charge of the uniformity process and who have ergonomic risks following Hazard Identification and Determining Control (HIRADC), as many as 93 operators are willing to participate, the results of Medical Check Up 2020 are fit to work or fit with notes (not related to ergonomics cases). Meanwhile, the exclusion criteria were not an operator level, suffering from congenital deformities or trauma caused not by working conditions.
Data were collected by observation and using a questionnaire. The level of ergonomic risk is assessed based on the Rapid Entire Body Assessment (REBA) sheet (Middlesworth, 2014) which analyzes work posture, workload, repetition, and static position. To collect data on operator characteristics and MSDs symptoms using a Nordic Body Map (NBM) questionnaire, which collects information about the location of discomfort by referring to certain body areas or by using partial or full body diagrams that designate certain areas to be assessed, namely the upper and lower extremities.
on the SNQ (the Standardized Nordic Questionnaire) on the neck, shoulders, elbows, wrists, upper and lower back, hips/thighs, knees, ankles/feet (Sauter et al., 2005).
Figure 1. Nordic Body Map (NBM)
The data analysis method used univariate analysis to get an overview of the frequency distribution of each variable and bivariate analysis to see the relationship and magnitude of the relationship between the independent variables (age, years of service, and education) and the dependent variable (MSDs symptoms).
RESULTS AND DISCUSSION
The operator’s demographic characteristics are presented in table 1. The majority of workers were 30-45 years old (46.24%), most of the respondent has more than 10 years of service (49.46%) and the majority of the respondent was in senior high school (92.47%).
Table 1. Demographic Characteristics of The Respondents
Respondents Characteristics Amount
n %
Age
< 30 years old 42 45.16
30-45 years old 43 46.24
> 45 years old 8 8.60
Years of service
≤ 5 years 3 3.23
6-10 years 44 47.31
> 10 years 46 49.46
Education
Senior High Schools 86 92.47
Academy (DI,D II,DIII) 2 2.15
Bachelor Degree 5 5.38
Employees who worked in the uniformity process had different postures which could have a diverse risk of injury from ergonomic problems while working in four different activities or processes, there booking process, uniformity input process, uniformity output process, and balancing process. The REBA score of each activity or process is shown in table 2.
Table 2. Ergonomic Risk Levels
Activity Reba Score Risk level Corrective action
Booking process 8 High Investigate and implement change
Uniformity input process 6 Medium Further investigation, change soon
Uniformity output process 7 Medium Further investigation, change soon
Balancing process 6 Medium Further investigation, change soon
Activity in the booking process was found in having an ergonomic risk level high (8), which was required for investigating and implementing change. In uniformity, the output process has a risk of 7 (medium risk) which needed further investigation and change soon. Two activities processes have risk at level 6 (medium risk), there are in uniformity input and balancing process, which was required further investigation and change soon.
Table 3. MSDs Symptoms
MSDs Symtoms Result Persentase (%)
Yes 88 94.62
No 5 5.38
Operators' MSD symptoms are represented in table 3. 88 respondents have MSD symptoms (94.62%) and 5 respondents do not have MSD symptoms (5.38%).
Prevalence of MSD symptoms by anatomic site showed differing prevalence for different anatomic sites. The ankles/feet were the area with the highest prevalence of MSDs symptoms (62.37%), followed by the lower back (56.99%), shoulders (55.91%), neck (49.46%), elbows and wrist/hands (44.09%), hips/thighs and knees (41.94%) and the lowest prevalence of MSDs symptoms were upper back (30.11%) (Figure 2).
Figure 2. Prevalence of MSD Symptoms
There was no significant correlation between age, years of service, and education with the prevalence of MSDs symptoms (p-value <0.05) (Table 4).
Table 4. Correlation between Age, Years of service, Education, and MSDs symptoms
Variable
MSDS Symptoms
Numbers pValue
Yes No
n % n %
Age
< 30 years old 40 43.01 2 2.15 42 0.725
30-45 years old 41 44.09 2 2.15 43
> 45 years old 7 7.53 1 1.08 8
Amount 88 94.62 5 5.38 93
Years of service
≤ 5 years 3 3.23 0 0.00 3 0.840
6-10 years 42 45.16 2 2.15 44
> 10 years 43 46.24 3 3.23 46
Amount 88 94.62 5 5.38 93
Education
Senior High Schools 81 87.10 5 5.38 86 0.807
Academy (DI,D II,DIII) 2 2.15 0 0.00 2
Bachelor Degree 5 5.38 0 0.00 5
Amount 88 94.62 5 5.38 93
58 39 39 53 41 41 28 52 46
62,37%
41,94%
41,94%
56,99%
44,09%
44,09%
30,11%
55,91%
49,46%
0 20 40 60 80 100
ankles/feet knees hips/thighs lower back wrists/hands elbows upper back shoulders neck
Prevalence of MSDs symptoms
Respondent Percentage
Uniformity final inspection activities had different processes as follows: booking, uniformity input, uniformity output, and balancing process. Each process could have diverse risks of injury from ergonomic problems while working. The following ergonomic risk of each process:
1. The booking process involves activities such as lifting, pushing, sliding, pulling, bending, twisting, and reaching awkward positions. Consists of lifting the tires from the conveyor to the trolley, shifting the tires, arranging the tires on the trolley, pushing the trolley to be carried to the next process, pulling the trolley, and positioning the trolley. In this process, all activities have diverse risks of ergonomic problems for employees. Activities performed repeatedly will disrupt the musculoskeletal system in the employees. The Reba score is 8, which means the level of ergonomic risk is high and was required to investigate and implement change.
2. The uniformity input process involves activities such as lifting, pushing, sliding, pulling, and reaching in awkward positions. These activities are lifting the tires from the trolley to the conveyor, rolling the tires to the uniformity input machine, pushing the tires on the conveyor to position it properly, and positioning the tires on the machine. In this process, all activities are suspected to cause operator uniformity to be exposed to ergonomic risks in the work environment, except for the activity of positioning tires on the conveyor. Activities performed repeatedly will disrupt the musculoskeletal system of the operator. The Reba score is 6 means that the level of ergonomic risk is moderate, this condition needs further investigation and change soon.
3. The uniformity output process, involves activities such as lifting, pushing, and pulling. These activities are lifting tires from conveyor to trolley, pushing tires into the trolley, and pulling tires from conveyor to trolley. In this process, all activities are suspected to cause operators to be exposed to ergonomic risks in the work environment. Activities carried out repeatedly will cause disturbances to the musculoskeletal system of the operator. The Reba score is 7 means that the level of ergonomic risk is moderate, this condition needs further investigation and change soon.
4. Balancing process, while working there are activities of lifting, pushing, sliding, pulling, and reaching awkward positions. These activities are lifting tires from racks to conveyors and vice versa, shifting tires, and arranging tires on the trolley. In this process, all activities are suspected to cause operators to be exposed to ergonomic risks in the work environment. Activities performed repeatedly will disrupt the musculoskeletal system of the operator. The Reba score is 6 means that the level of ergonomic risk is moderate, this condition needs further investigation and change soon.
The highest ergonomic risk is in the booking process with a 'high' level of REBA, activities that have the potential for ergonomic risk are lifting tires manually with a load of 12-30.9 kg from the conveyor to the trolley, there are activities placing tires on the trolley that are arranged high enough that they are above the workers' upper arms, reach more than the upper shoulders, manual handling methods when lifting tires from the conveyor are lifted in a lower position (near the feet) instead of approaching
the body, bending position when moving tires from the conveyor and the activities are done repeatedly.
The REBA score is in line with the research conducted by Bahardin et al. (Kamal Bahardin et al., 2018), in this study studied the prevalence of MSDs in tire manufacturing workers and assessed the level of ergonomic risk using REBA. The majority of workers (86.3%) in their study were exposed to 'very high (11+) and 13.7% were exposed to a 'high' level of ergonomic risk. However, they studied the sequence of the most critical and ergonomic risk-intensive tasks that were formed as part of the manual lifting of the tread layer. The study of Supooto et al. (Supooto et al., 2020),showed the same results on tire manufacturing workers and assessing the level of ergonomic risk using REBA, the focus of this research is assessing ergonomic risks on the task (characteristics of the task). The majority of work tasks with a 'high' ergonomic risk value of 42.86%, a 'very high' work task risk value (11+) of 28.57%, and a 'medium' and 'low' risk value of 14.29 %.
The prevalence of musculoskeletal pain in car/tire manufacturing workers involving joints was reported in the range of 14.14% to 50.98% in the neck, 15.15% to 76.47% in the shoulder, 19.19% to 58.82% in the upper back, 5.05% to 52.94% at the elbows, 6.06% to 62.75% at the wrists, 24.24% to 72.55% at the lower back, 19% to 60.78 % on hips/thighs, 16.16% to 43.14% on knees, and 20.20% to 54.90% on legs and feet (Mukkamala et al., 2021 and Kamal Bahardin et al., 2018). The results of the Body Nordic Map questionnaire were obtained from 93 uniformity operators who experienced MSDs complaints as many as 88 people (94.62%), the highest symptom was experienced by uniformity operators on the heel/foot as many as 58 people (62.37%) and the least symptom were on the upper back as many as 28 people (30.11%). In the work activities of uniformity operators who experience the most symptoms in the heel/ foot joints from the observations it is known that due to the heavy load being lifted between 12-30.9 kg by carrying out manual handling activities, lifting / lowering tires repeatedly with the position of stacking tires on the truck exceeding the operator's shoulders, there is an activity of pushing and/or pulling trolley from the booking area to the uniformity/balancing machine with a distance of 6-30 meters repeatedly.
The above conditions according to the National Institute for Occupational Safety and Health (NIOSH) are the main risk factors that can cause injury in manual material handling which include activities: 1) awkward postures, e.g. bending over, 2) repetitive movements, e.g. lifting, carrying, frequently reaching, 3) Strong exertions, e.g. carrying or lifting heavy loads, 4) Pressure points, e.g.
grasping or contact of the load, leaning on hard parts or surfaces or having sharp edges, 5 ) Static posture, for example, maintaining a fixed position for a long time (NIOSH, 2007). NIOSH recommends the maximum load under ideal lifting conditions i.e. RWL (Recommended Weight Limit) is considered as a load of 23 kg, lifted in a sagittal plane (right in the middle of the body both vertically and horizontally in body position) from a height of 75 cm above the floor and held 25 cm in front of the body. The load should be lifted no more than 25 cm vertically and the load should only be lifted
occasionally (Bridger, 2003). In the Uniformity operator activity, it is still found that the lifting position is not ideal, namely, the load exceeds the RWL with the manual lifting method, done repeatedly and stacking the tires in a position above the shoulder (not sagittally).
Of 93 uniformity operators, and 88 operators who experienced MSDS symptoms, the highest age group experiencing MSDS was from the age of 30-45 years, namely 41 people (44.09%). From the results of the test using a chi-square p-value (0.725)> 0.05, it can be concluded that there is no significant relationship between age and MSDs symptoms. The results of this study are different from other studies conducted by Sulistiyo et al. (Sulistiyo et al., 2018), the study showed there is a relationship between age and MSDs symptoms, so the older you get, the higher the complaints against MSDs.
Of 88 operators, who had a prevalence of MSDs symptoms 43 people (46.24%) operators with a working period of > 10 years experienced MSDs symptoms and the least experienced MSDs symptoms were operators with a service period of < 5 years as many as 3 people (3.23%). The test results using chi-square p-value (0.840)> 0.05, it can be concluded that there is no significant relationship between tenure and MSDs symptoms. The same results were obtained from the research conducted by Bahardin et al. (Kamal Bahardin et al., 2018) that there is no relationship between age, BMI, and years of service on MSDs symptoms based on the results of chi-square tests (p-value > 0.05).
Of 88 operators, who had a prevalence of MSD symptoms, the most MSD symptoms were felt by operators with high school education as many as 81 people (87.10%). From the results of the test using a chi-square p-value (0.840)> 0.05, it can be concluded that there is no significant relationship between education and MSDs symptoms. Andorsen et al. (2014) in their cohort study of the Norwegian population in general found a negative relationship between education level and musculoskeletal symptoms, the results suggest paying attention to low levels of education may have positive results in preventing musculoskeletal symptoms (EU-OSHA, 2019). Similar findings were reported by the EMUSC study (2019) on musculoskeletal health in Europe. In particular, according to this study, workers with low levels of education often tend to report more work-related problems and they are more likely to report MSDs as the most serious work-related problems. In addition, the EMUSC study underscores the importance of patient education as a factor enabling them to understand and manage musculoskeletal conditions (Eumusc, 2019).
CONCLUSION AND SUGGESTIONS
Ergonomics risks in the work activities of uniformity final inspection operators are mostly moderate to high, the highest risk is in the activity or booking work process, this is because there are activities of lifting tires from the conveyor to the trolley, shifting tires, arranging tires on the trolley to placing them on the workers' shoulders, pushing the trolley to be taken to the next process and this activity is carried out repeatedly.
The highest proportion of MSD symptoms was in the heel/toe joint, while the lowest proportion was in the upper back. These MSDs symptoms are not related to age, years of service, and education.
We recommend reducing the ergonomic risk in uniformity final inspection to provide lifting aids for manual handling work with loads above the standard that is > 23 kg. It is necessary to provide job training or training on ergonomic risks in the workplace and work procedures following the required ergonomic principles. In addition, it is necessary to provide Personal Protective Equipment (PPE), such as back support to prevent muscle injury, perform appropriate work and rest times and try to work following the power zone.
ACKNOWLEDGMENT
Thank you to the company that has been willing to become a place of activity and also to thank the University of Muhammadiyah Jakarta which has provided support for this research activity.
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