Iranian Journal of Ergonomics

Investigating the Relationship between Ergonomics and Postural Abnormalities in Manufacturing Industries

Hadi Miri

Objectives: In today's advanced world, musculoskeletal problems are among the most serious problems. The present study aimed to assess the relationship between ergonomics and postural abnormalities in manufacturing workers.
Methods: The statistical population of this research consists of 210 male employees working in two production units. Among this population, 134 cases were included in the study according to Morgan's table and based on the inclusion criteria. The pain in different parts of the body was assessed by the Nordic Musculoskeletal Questionnaire, the Rapid Entire Body Assessment (REBA) was utilized to evaluate workplace ergonomics, and the body posture was evaluated by the New York Posture Rating. The collected data were analyzed in SPSS software (version 26). The Shapiro-Wilk test was used to investigate the normality of data distribution. Moreover, a linear regression statistical test was utilized to assess the relationship between research variables. The significance level was set at <0.05.
Results: The obtained results pointed to a significant and negative relationship between the ergonomics score and the physical condition assessment (P=0.00; R=0.60). In addition, the results highlighted the presence of skeletal-muscular disorders in different parts of the body, with the highest prevalence in the back (53.73%).
Conclusion: According to the high and negative correlation of the variables, it was found that unfavorable ergonomic conditions can lead to poor physical condition and numerous musculoskeletal consequences.

Performance of Vests based on Nanofibers and Packages of Phase Change Materials to Reduce Thermal Stress in a Hot Work Environment: An Experimental Study

Mohsen Aliabadi

Objectives: This study aimed to investigate the effectiveness of cooling vests based on nanofibers and packages of phase change materials (PCM) in reducing the thermal stress of medical personnel in hot workplaces.
Methods: In this experimental study, 20 males were exposed to 10 combined scenarios of temperatures of 24°C and 32°C in a room simulating atmospheric conditions and having 5 samples of cooling vests. Physiological parameters, including skin surface temperature, tympanic temperature, and oral temperature were measured before and after exposure to air temperature conditions by simulating the activity metabolism of hospital workers. The normal distribution of the data was checked with the Kolmogorov-Smirnov test, and the analysis of the effect of the scenarios was performed through the analysis of variance with repeated measurements.
Results: The results confirmed that in the condition without a vest, the air temperature of 32°C compared to the air temperature of 24°C had a greater effect in increasing the tympanic body temperature (P<0.05). The significant effect of using nanofiber vests along with PCM packages was observed in reducing skin temperature, tympanic temperature, and oral temperature in hot temperature conditions with effect sizes of 0.498, 0.568, and 0.349, respectively (P<0.05). The effect size of increasing the air temperature was lower than that of the type of cooling vests on the physiological responses, indicating that the effectiveness of the designed vests is enhanced with an increase in temperature (P<0.05).
Conclusion: The use of nanofiber cooling vests and PCM packages is effective in maintaining the body temperature stability of medical personnel in hot environments due to ideal weight and acceptable effect size.

Evaluation of Comfort, Usability and Posture of an Ergonomic Sit-stand Desk Converter Developed Based on Anthropometric Data from an Iranian Community

Arezoo Sammak Amani

Objectives: Nowadays, workers are less mobile and more sedentary due to the use of modern technologies in the workplace, and the complications resulting from static work and fixed posture have caused numerous disorders, including musculoskeletal disorders. This study was conducted to evaluate the comfort and usability of the ergonomic sit-stand desk converter with the aim of preventing disorders caused by constant sitting in workers.
Methods: 30 employees and faculty members of a university voluntarily participated in this study and provided informed consent. After the necessary explanations, subjects were provided with two researcher-created questionnaires ( Local Perceived Discomfort (LPD) and Sit-Stand Desk Converter Usability Questionnaire (SSDCUQ)), two methods of posture analysis, two methods of Workstation evaluation and general satisfaction along with 20-8-2 software and an ergonomic desk converter. After the test period, the data was analyzed using SPSS version 22 software and statistical tests such as mean, standard deviation, Spearman's rank correlation coefficient and Pearson correlation coefficient.
Results: The overall mean LPD in the different body parts was 0.48 ± 0.87, indicating that the converter functions in the range of no problem to very little discomfort. The average overall satisfaction with the function of the converter was 3.18 ± 1.08 ,which is in the medium to good range. When analysing the different sitting and standing postures, a significant correlation was also found between the different situations of using the converter (P<0.0005), which indicates an improvement in sitting and standing posture while using the converter.
Conclusion: Height-adjustable workstations are a good choice to reduce sitting time and improve posture. Despite the improvement in sitting and standing posture when using the converter, there are limitations, such as ignoring the software warnings for sitting and standing in the mechanical converter studied.

Investigating Psychometric Properties, the Workers’ Psychological Burden from the Perspective of Occupational Safety and Health

Maryam Hasani

Objectives: Psychological load, such as workload, not only disrupts work performance but can also directly affect employee safety leadin to accidents. However, despite this issue, not much effort has been made to develop an assessment tool to measure the psychological burden related to the occupational safety and health of employees. Therefore, the present study was designed to validate the psychological burden scale of workers by Kim et al. (2018) from the perspective of occupational health and safety.
Methods: The statistical population of the research consisted of all the workers employed in the Eastern Alborz Company of Shahroud city, and 349 workers participated in the research using a simple random sampling method. In the present study, the mental load scale by Kim et al. (2018), the Copenhagen psychosocial scale (COPSOQ), and the occupational stress scale (HSE) were used. The data were analyzed using Pearson's correlation coefficient tests and confirmatory factor analysis using SPSS version 22 statistical software and Lisrel version 8.5.
Results: The results showed that all the components of workers' psychological burden including the overall score and the psychosocial scale and occupational stress scale have a positive and significant relationship. The results of the confirmatory factor analysis also indicated a good fit of the model in determining the factors in the initial form as proposed by Kim et al. (2018). To determine the reliability of the scale, the value of Pearson's correlation coefficient was obtained at 0.82 in the test and retest phases. Additionally, the results of this study showed that 26.1 percent of workers experienced low psychological burden, 49.6 percent experienced moderate psychological burden, and 24.4 percent experienced severe psychological burden.
Conclusion: Based on the results of the current research, the workers' mental burden scale (Kim et al., 2018) is a valid and reliable tool that can be used to evaluate the psychological burden of workers in research and intervention studies.

Investigating Effort-Reward Imbalance Model in Predicting Workplace Bullying

Mehraneh Shabani

Objectives: In work environments, job stress is the main factor that can make employees lose control and provide the opportunity for the occurrence of aggression in employees. Therefore, this study investigated the role of the effort-reward imbalance model in the occurrence of bullying in the workplace.
Methods: This study was descriptive-analytical in nature. The research population consisted of employees of one of the petrochemical plants located in the south of the country. The samples (n=202) were selected using the census sampling method. In this research, two self-report questionnaires, namely the Effort-Reward Imbalance Scale and the Questionnaire of bullying actions, were used to measure the variables. Data analysis was performed using SPSS 18 software using Pearson’s correlation coefficient and linear regression.
Results: The mean scores of the participants’ age and work experience in this study were 40.13±9.32 and 15.9±9.50 years, respectively. Among the participants, 72.8% were female and 86.1% were married. In terms of educational status, 10.9% had an associate's degree, 81.2% had a bachelor's degree, and the rest had a master's degree or higher. About three-quarters of the participants were public service employees, and the rest were working on a contract basis. Based on the results of the multivariate regression model, among the variables investigated in this study, effort-reward imbalance and extreme commitment were able to significantly predict the changes in the bullying score (P<0.001).
Conclusion: Employees who feel imbalanced between inputs and outputs in the job, as well as those who have the characteristic of excessive responsibility, are more likely to display negative behaviors in the form of bullying in the workplace.

Studying the Effect of Likert’s Scale Starting Point on Descriptive and Analytical Findings of Questionnaire

Ali Reza Soltanian

Objectives: There is currently no consensus on transformation of the starting point of scoring on the Likert’s scale in questionnaires. This study aimed to investigate the effect of the transforming the starting point of scoring on the indices of central tendency, dispersion and the independent t-test.
Methods: The study employed inferential analysis to investigate the effects of transforming the origin of scoring, comparing the results through illustration. A 4-point Likert’s scale, starting with scoring zero and one, was utilized. The Independent t-test was used to compare the mean scores in two groups.
Results: The results of the study showed that transforming of the starting point of scoring from 1 to zero on Likert’s scale only leads to a difference in the value of the tendency to the center. However, dispersion indices and statistical statistics did not showed any difference in both scoring methods.
Conclusion: Changing the origin of scoring in the questionnaires, when total scores exhibit a normal distribution, has no impact on the independent t-test and standard deviation. The only significant affect includes difference on tendency to the center in two scoring systems.

The Impact of Musculoskeletal Disorders and Occupational Risk Factors on the Physical Status of Iranian Healthcare Workers: A Systematic Review

Mehran Maleki Roveshti

Objectives: Musculoskeletal disorders are an important issue in many healthcare work environments. The aim of this systematic review is to investigate musculoskeletal disorders and occupational risk factors on the physical status of medical staff in Iran.
Methods: In this systematic review, eligible studies from national and international databases, such as PubMed, Embase, Web of Science, Scopus, SID, Magiran and IranMedex from 1390 to 1400 were independently analyzed by two researchers based on the preferred reporting cases of the Guidelines for Systematic Reviews and Meta-Analysis (PRISMA) . MeSH keywords and phrases were used to implement the search strategy.
Results: Of the 360 articles, the full text of 24 articles was finally examined. The results of the study showed that the highest prevalence of musculoskeletal abnormalities and complaints among workers in the last 12 months was related to neck pain (46.01%). Furthermore, among the 24 occupational risk factors identified, prolonged standing (20.83%) and repetitive movements (16.66%) are the most important factors for the occurrence of physical complaints among healthcare workers.
Conclusion: The results of this study can play an important role in strengthening and improving the country's health system in terms of individual, administrative and organizational measures in health centers. In this way, the physical needs, the psychological and ergonomic stresses of the working environment and the health of the treatment staff can be improved.

Investigating the Effectiveness of Safety Interventions to Reduce Traffic Accidents in Pregnant Women: A Systematic Review

Maryam Afshari

Objectives: Traffic accidents are one of the leading causes of death among pregnant women. One of the investment for maternal and neonatal health is targeted interventions to increase maternal safety to prevent traffic accidents. Therefore, this study was conducted with the aim of identifying and categorizing different types of safety interventions to reduce traffic accidents among pregnant women.
Methods: The study was a systematic review. Intervention articles were searched from Persian databases, such as Magiran, Iran Medex and SID and English scientific information databases, such as PubMed, Cochrane, Sciencedirect, Embase, Science of Web and Scopus. All identified articles were collected by one person using Endnote software. The full text of the articles was then reviewed by two researchers and the articles that met the entry criteria were identified. Other articles were added to the previous collection of articles using Forward Citation and Backward Citation Reviews. The EPHPP instrument was used to assess the quality of the studies.
Results: The initial search resulted in finding 5329 article abstracts. Finally, two intervention studies were selected for evaluation in this study. One study used an educational/behavioral approach and the other used an engineering/approach. Both studies reported that they had produced significant changes in the desired outcome of seatbelt use in pregnant women. The quality of one study was rated as poor and the other as moderate.
Conclusion: Safety interventions to reduce traffic accidents among pregnant women have been tested only to a very limited extent worldwide. It seems that there is still much room for study in the field of safety interventions to reduce traffic accidents among pregnant women.