Iranian Journal of Ergonomics

Introduction: Using human data and observing local manufacturers of domestic products for imported furniture seems necessary to design and manufacture sofas with ergonomic indices. This paper uses data from the study of human population. The design process from the perspective of ergonomic furniture and product design consists of ergonomic principles such as shape and posture in the correct state and consideration of parts of body that need cushion for protection.

Methods: In this research, anthropometric data of 150 males and 110 females between the ages of 25 to 35 were measured. The calculations were based on a sample size sofa to gather user evaluation.

Results: After analyzing the measured results of a similar internal investigation using SPSS software and combining them with ergonomic principles, the optimal size sofa measurements with all angles for Iranians adults was calculated and the results were compared with the dimensions of the furniture.

Conclusions: Seat height and backrest height and width, respectively 37, 57 and 62 cm, the angle of 105 degrees between the seat and the back, and the slope of 5 degrees for the seat surface are suggested as the standard.

Introduction: Work-related musculoskeletal disorders (WMSDs) are the most common occupational health problems, reported with high costs and loss of productivity in nurses. On one hand, the quality of life is a multidimensional concept that affects factors such as physical and psychological ones. This study aimed to evaluate the relationship between WMSDs and quality of life in nurses.

Methods: This descriptive-analytical study was performed on 940 nursing staff in Hospitals of Sari, Iran. The samples were selected by census sampling method. Data were gathered using particular questionnaires of musculoskeletal disorders (Nordic) and quality of life (SF-36). Collected data were analyzed by analysis of variance (ANOVA), t-test and Pearson's correlation using SPSS software (version 18).

Results: The results showed that low back disorder with prevalence of 60.9% was the most prevalent disorder among nurses. All aspects of quality of life, except for social functioning, were significantly correlated with WMSDs (P<0.05). In addition, there was a statistically significant relationship in age, gender and education level with WMSDs as well as in gender and work with quality of life (P<0.05).

Conclusions: According to this study, the prevalence of WMSDs was relatively high in nurses. In the majority of nurses, moderate quality of life was observed. Therefore, any intervention to improve quality of life and prevent WMSDs should be focused on, to reduce the physical needs and psychological pressures.

Introduction: Musculoskeletal disorders are the major health problems in nurses. One of the main reasons is patient transfer. The work technique of nursing personnel during patient transfers has been evaluated using different methods. One of the most useful ones is Direct Nurse Observation Instrument (DINO). The purpose of the present study was to assess the musculoskeletal disorders risk related to patient transfer in nursing personnel using the DINO method.

Methods: This cross-sectional study was carried out among 250 nurses working in affiliated hospitals of Isfahan University of Medical Sciences, Isfahan, Iran in 2015. Data were collected by Nordic questioners and DINO index check list. The validity and reliability of DINO checklist were reviewed and approved. For data analysis, independent t-test, chi-squared test and logistic regression were used.

Results: The average result of DINO checklist was 9.73 points (SD = 1.8), which can suggest that the way in which the technical transfer was carried out might not have been the safest. The results showed that the occurrence of musculoskeletal disorders in nursing staff was significantly associated with final scoring of the DINO index (P < 0.001).

Conclusions: According to the findings, DINO was an appropriate tool to assess musculoskeletal disorders risk due to patient handling in the nursing personnel. This method can be used in the evaluation of patient transfer educational programs and also to identify and assess an unsafe work techniques used by nurses.

Introduction: Foot anthropometric dimensions could be useful in designing comfortable footwear. The objective of this study was the measurement of foot anthropometric dimensions in a group of students.

Methods: This was a descriptive study in which 21 dimensions of foot for 580 males and females were measured manually. To measure the foot dimensions, a digital caliper and a tape were used. The measured dimensions included the important lengths, widths, heights and girths of foot. Descriptive statistics such as percentiles, mean and standard deviation were calculated for the collected data. To test and survey of the mean of foot dimensions between males and females, statistics such as independent t-test and effect size (Cohen’s d) were used.

Results: The values of mean, standard deviation, the 5th, 50th, and 95th percentiles were calculate and tabulated for the total studied population and for gender. In all measured foot dimensions, males had bigger dimensions than females. Gender had different impacts on the measured foot dimensions. The mean of all foot dimensions was significantly different between males and females (P value = 0.001). Digital pattering of I and II were observed in 78% and 22% of the studied population, respectively.

Conclusions: In the present study, important anthropometric data of foot were collected for a group of students. The presented percentiles could be used in design of male and female shoes. Conducting similar studies in children with different age categories could help completion of the anthropometric database.

Introduction: Low back pain is the most common cause of chronic pain syndrome which leads to activity limitation in people younger than 45 years old.

Objectives: This study aimed to evaluate the relationship between severity of low back pain and work limitation in patients with acute and chronic low back pain.

Methods: Ninety patients with acute and chronic low back pain who attended the rheumatology Clinic of Booali Hospital were evaluated in this cross-sectional study. A questionnaire containing demographic information and one about the onset and cause of low back pain were asked from patients. Work Limitation Questionnaire was asked from patients. Severity of pain was measured by Visual Analogue Scale. All the data were analysed using SPSS software.

Results: The results showed that the most common cause of low back pain was discopathy with 33 patients (36.7%). There was no significant difference between males and females in terms of work limitation (P = 0.66). Patients with discopathy showed the most severe work limitations (72%). Also, there was a significant relationship between severity of work limitation and patients' age. Older patients had more severity of work limitations (P < 0.001, r = 0.42). There was a significant correlation between work limitation and severity of pain. Patients with increasing pain had more severity of work limitations (P < 0.001).

Conclusions: Our results showed that with increasing age and pain work limitations will increase due to low back pain.

Introduction: Many employees in different professions including nurses work with shifts. On the other hand, different and long shift work  can endanger physical and mental health of nurses. This study, according to ergonomic standards, aimed to design a model for shift working in order to minimize the problems caused by shift work.

Methods: In this study, all 35 nurses working in the emergency ward of Imam Sajjad (AS) Hospital of Ramsar city, Iran, were considered. Then, the information gathered from answering the Morningness-Eveningness questionnaire (MEQ) (Circadian rhythm) and Survey Sampling International (SSI) (personal and social charactristics) questionnaire were changed to a model and then reconstruct after comparing it again with circadian rhythm principals. The final model was implemented with GAMS (gamma-glutamylaminomethylsulfonic acid) and at the end, shift working with ergonomic criteria were proposed.

Results: Shift working were designed for each nurse. Also, the obtained objective function value (Z=1.110223e-16) showed that the designed model was really close to ideal model. According to hospital rules and policies, if five more nurses get added to the currently employed ones, the proposed working program on one hand will improve satisfaction and efficiency of nurses and on the other hand it can decrease the effects of disorders on shift work.

Conclusions: Hospitals can have healthy and motivated workforce by applying the scientific approach to adjust a suitable working plan for their nurses and decrease the number of disabilities and also the rate of early retirement.

Abstract                                                                

Introduction: Job stress such as role ambiguity, a situation that arises from the interaction between people and jobs, reduces the performance and job satisfaction. Proactive people eliminate ambiguity in their jobs by behaviors such as innovation. The present study aimed at investigating the impact of proactive personality on job satisfaction and performance mediated by information seeking.

Methods: The statistical population of this survey consisted of the official staff and contractual personnel of Bid Boland gas refinery, from whom 260 were selected using the hierarchical random sampling method. The research design of this study was correlation, through structural equation modeling. The data collection tools were Role Ambiguity Scale, Proactive Behavior Questionnaire (Ashford and Black), Job Satisfaction Questionnaire (Brayfield & Rothe), and Job Performance Questionnaire (Paterson). The assessment of the proposed pattern was conducted through path analysis.

Results: The results supported the suitability of the relationship between the patterns and the collected data. The results revealed that proactive behavior mediated the effect of role ambiguity in job satisfaction and performance. All the routes in the research model were meaningful (P < 0.001) and the overall fit index [root mean square error of approximation (RMSEA)] was 0.04, which represents an excellent fit pattern.

Conclusions: Proactive behavior eliminates uncertainty for employees and finally eliminates the negative effects of role ambiguity on job performance and satisfaction and leads to increased performance and satisfaction of employees.

Introduction: In the recent decades, owing to the advancement of technology, most jobs and occupations require the use of computers. Lack of information about ergonomic conditions has resulted in various occupational injuries. Break time between work and doing exercise, help in reduction of musculoskeletal symptoms. The present study aimed to use a new ergo-feedback software and to assess its usability in office staff.

Methods: Thirty office staff participated in this study. In the first step, muscle-skeletal symptoms were checked by a body map checklist. Then, the Borg score was determined by the participants, initially and after one work day. The software was then run in their systems and they worked with it for about two weeks. After two weeks, the Borg scale was completed again and efficacy of the software was evaluated by the system usability scale (SUS). Data analysis was performed using descriptive statistics (mean and standard deviation) and Wilcoxon test. Statistical analysis was done by the SPSS software version 19.

Results: The results showed that there was a significant difference between the Borg score pre and post intervention (P > .05). The majority of the users were satisfied with the software with the SUS score showing about 82.25% satisfaction.

Conclusions: According to this study, office workers were satisfied with using this software and it can help reduce musculoskeletal symptoms during a prolonged time period.

Introduction: Nominal noise reduction rate of the earmuff manufacturers can be different compared with the actual attenuation rate. The present study aimed to determine the actual noise reduction rate of common hearing protection devices using microphone in real ear method.

Materials and Methods: In this study, five brands of common earmuffs used in Iranian industries were investigated on 30 subjects under laboratory conditions. Noise reduction rates of earmuffs were measured based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK, SV 102 model) equipped with a microphone SV 25 model. The earmuffs comfort was also assessed by the developed questionnaire.

Results: The results showed that the real noise reduction rates of the earmuffs were between 49% to 86% of nominal reduction rates. Moreover, the actual insertion losses were much negligible at low noise frequencies. The performances of earmuffs based on manufacturers were not statistically different (Pv> 0.05). Based on subjects’ comfort scores, comfort of ear muffs were within the acceptable range. The noise reduction rates of the different earmuffs of each model were not statistically different as well (Pv > 0.05).

Conclusions: Irregular use of earmuff can reduce the real attenuation of earmuff to lower than the minimum rate acquired in this study. Proper training and adequate supervision on proper use of earmuff can affect earmuff fitting along with increasing of real noise attenuation.

Introduction: Nursing in hospitals, because of the nature of the work, is a job in which work-related musculoskeletal disorders are highly prevalent. The main cause of musculoskeletal disorder amongst nursing staff is the movement of patients. The aim of this study was to evaluate the risk of musculoskeletal disorders caused by movement of patients in nursing staff of a hospital affiliated with the Allah University of Medical Sciences.

Methods: This cross-sectional study was conducted on 325 nurses from 30 wards of Baqiyatallah hospital during summer 2015. Data were collected using demographic and Body map Musculoskeletal Disorders Questionnaires and PTAI index checklist. Statistical analysis was performed using the SPSS software version 16.

Results: Some musculoskeletal symptoms had been experienced during the last 12 months by 78.3% of the nursing personnel. The results indicated that PTAI index score was significantly associated with musculoskeletal disorders occurrence (P < 0.05)

Conclusions: According to the findings, PTAI is an appropriate tool for musculoskeletal disorders risk identification and assessment due to patient handling in nursing personnel.

Introduction: Job stress is identified as imbalance between job needs and individual’s abilities and demands. Job stress has somatic, psychological and behavioral traumas, The main purpose of the present research was to investigate the effects of employees' job stress level on the emersion of organizational behavior amongst Mazandaran's SAMEN Finance and Credit Institute's subdivision employees.

Methods: In this correlation-descriptive study, 147 employees from SAMEN subdivisions of Mazandaran province were selected based on the census sampling method. Data were collected by using the job stress and organizational citizenship behavior standard questionnaire. Data were analyzed by the SPSS and LISREL software, and using descriptive statistics, Pearson’s correlation and Standard Error of the Mean (SEM).

Results: In the current study, there was a significant and inverse relationship between job stress and organizational citizenship behavior (R = -0.590, and P = 0.001). The results of structural equation modeling and path analysis showed that job stress and most of its components were good predictors of organizational citizenship behavior.

Conclusions: Recent research has demonstrated that job stress may increase employees-related problems. There is a relationship between job stress and organizational citizenship behavior, and attention to job stress level as a predictor of organizational citizenship behavior in employees is an essential issue.

Introduction: Sleep disorder is very common among employees and is considered as one of the crucial health problems. Sleep disorders have a negative impact on job performance. The present study was regarding the relationship of sleep quality, sleepiness and sickness absence.

Methods: This cross-sectional study was conducted on 400 employees of a gas company through random sampling. The study data were collected using the Pittsburg Sleep Quality Index (PSQI) and the Karolinska Sleepiness Scale (KSS). Mann-Whitney U test and Spearman’s correlation coefficient were applied for data analysis.

Results: While 43.2% of the participants enjoyed satisfactory sleep quality, 56.8% had unsatisfactory sleep quality. Statistical tests indicated a significant difference in sickness absence of the personnel with good and poor sleep qualities (P = 0.0001). Spearman’s correlation coefficient (ρ = 0.777) indicated a statistically significant correlation between sleepiness index and sickness absence (P = 0.0001).

Conclusions: The results showed a strong positive correlation in sleep quality, sleepiness index of the personnel and sickness absence; i.e. along with decline in sleep quality and incline in sleepiness, the personnel’s sickness absence increased.

Introduction: Firefighting is amongst jobs that require high physical strength and high aerobic capacity. These are required because of the nature and the physical demands of the job. The maximum aerobic capacities of firefighters were investigated using the step test.

Methods: This cross-sectional descriptive-analytical study was conducted on 73 firefighters. At first, demographic information was collected by a questionnaire. Then, the step was built with adjustable height, for step testing, and using the Francis method, maximum aerobic capacity of the participants, was studied. The results of the questionnaire and step test were analyzed by the SPSS 16 software.

Results: maximum aerobic capacity of firefighters was calculated as 3.65 L/min and 47.4 mL/kgmin. Moreover, the results of statistical analysis revealed a significant relationship between body mass index and exercise, and maximum aerobic capacity (P ˂ 0.05). Also no significant relationship was found between maximum aerobic capacity, age, smoking and work-related fatigue (P > 0.05).

Conclusions: Studying the firefighters cardiorespiratory capacity, to reduce the probability of firefighters injuries is very important due to occupational sensitivity and having to perform difficult tasks under demanding circumstances. The results of this study showed that maximal oxygen uptake (vo2 max) and cardiopulmonary capacity of examined firefighters are greater than the minimum amount recommended by the international association of firefighters, which can be due to regular physical fitness programs conducted by the organization.

Introduction: work engagement is a stable and positive state of mind associated with work, which protects against job burnout. This study was conducted to determine the contribution of goal orientation, perceived organizational support and Big Five personality traits in predicting job motivation of female teachers in Shahrekord, Iran.

Methods: The design of the study was correlational-survey. The sample included 230 female teachers in Shahrekord, teaching in high school during 2013-2014. The sample of the study was selected by cluster sampling. To collect data, goal-orientation, perceived organizational support, five factor inventory and job work engagement were administered to the participants.

Results: Correlation and step regression analyses were utilized to analyze the data. Findings of the study showed that there was a significant relationship among goal-orientation, perceived organizational support, Big Five personality traits and work engagement (P < 0.01). Furthermore, multiple regression analysis revealed that linear combination of goal orientation, perceived organizational support and Big Five personality traits could predict work engagement of teachers )P≤0.01).

Conclusions: the present study indicated that different components of personality, goal-orientation and perceived organizational support can create work engagement.

Introduction: The progress of technology and modern technology has changed today’s workplaces and imposed more mental and cognitive demands to workers. Control room is an example of these workplaces. Currently, assessment of mental workload is a key point in the research and development of human-machine relationships in workplaces. This study aimed to validate an analytical approach in evaluating demanded mental workloads for control room operators in Pars combined cycle power plant.

Methods: This was a fundamental-practical and cross-sectional study. First of all, a task analysis was used to understand the operation steps of control room operators. Then, the Visual, Auditory, Cognitive, Psychomotor (VACP) technique was applied to determine the mental workload demanded for performing each step of the works. Finally, the assigned ratings of the VACP method were validated by the analysis of Pearson’s correlation with the answers of the NASA-Task Load Index (NASA-TLX) questionnaire, collected from the control room operators.

Results: Based on the results, the correlation between the assigned ratings of VACP technique and the answers of the NASA-TLX questionnaire was positive and significant.

Conclusions: Due to the high correlation between the assigned ratings of VACP technique and the answers of the NASA-TLX questionnaire, the proposed VACP technique, which can be carried out in the early stage of the design, was suitable as an analysis tool for predicting metal workloads of control room operators.

Introduction: Shift work, in addition to its effects on physical, psychological and social status, may impact on oral health. The aim of this research was to assess the relationship between shift work and oral health in nurses.

Methods: This cross-sectional study was carried out on 120 nurses working in a hospital affiliated to Tehran University of Medical Sciences during 2014-2015. Oral health status and DMFT index (Decayed, Missing and Filling Teeth) was assessed by a dentist through clinical examination. Data were analyzed using SPSS 22 software, chi-squared test, independent samples t-test and multiple logistic regressions test.

Results: The results showed that the means of DMFT index in shift work nurses and non-shift work nurses were 8.10 ± 4.10 and 9.41 ± 2.8, respectively. There was no significant difference between decayed, missing and filled teeth and periodontal DMFT index in both groups. Multiple logistic regression analysis revealed that age was a significant predictor of DMFT indictor (P<0.001). No significant relationship was found in DMFT index with gravid, parity, family income, anxiety and work experience.

Conclusions: This study demonstrated that shift work was not an independent factor affecting oral health. However, regarding the DMFT index mean differences and nurses’ job responsibilities, it seems necessary to pay more attention to this occupational group.

Introduction: Musculoskeletal disorders (MSDs) are inevitable consequences of ergonomic principles neglect. The increasing use of computer by students may result in these disorders. Therefore, the present study was conducted to determine the prevalence of MSDs and evaluate the effectiveness of ergonomics training intervention among university students.

Methods: This interventional and cross-sectional study was performed on a group of medical and paramedical students. Samples were chosen by simple sampling method. In the first stage, data were gathered by means of a self-made measurement and Nordic Musculoskeletal Questionnaire (NMQ). Furthermore, an educational booklet regarding the principles of ergonomics in computer use (educational intervention) was offered to the subjects. In the second stage of the study, the effectiveness of intervention was evaluated using a written exam and a quasi-objective structured clinical examination (quasi-OSCE) test. Data were analyzed by SPSS 15, as well as descriptive and analytical statistical indexes.

Results: From 205 students participated in the first round of the study, the results showed that 62.44% of them (128 persons) reported at least one complain or limitation in their musculoskeletal systems during the past year. Less than 10% of the participants were aware about the considerations of ergonomics principals during computer use. After submission of the educational materials, their awareness about the ergonomics considerations in computer use significantly improved(P<0.001) and more than 95% of them had good or medium performance after the intervention.

Conclusions: The training program was effective on the awareness of ergonomics principles in computer use. However, prevention of musculoskeletal disorders requires complementary measures such as elimination of risk factors and administrative controls.

Introduction: Since faculty members are among the most important assets of higher education institutions, surveying and identifying factors associated with these sources that can be effective on their performance and stress have gained increasing importance. Accordingly, the present study was conducted to survey the relationship between personal accountability and job performance considering the mediating effect of skills and job stress among employees of the University of Shiraz.

Methods: The statistical population of this study consisted of all of Shiraz University staff who had high school diploma, which included 726 individuals. A sample of 256 persons was chosen using stratified random sampling method. The research method was descriptive-correlative. Data were collected using Hochwarter et al. (2005) accountability, job performance (1990) of Paterson, House and Rizzo’s (1972) Job tension and political skills, and Ferris et al. (2005) satisfaction standard questionnaires. The structural equation modeling (SEM) was used to study the relationship between the latent variables and the measured ones in conceptual model.

Results: The results showed that job performance was affected by personal accountability; employees who had political skills had more accountability, which significantly affected their job performance. Job tension had a significant negative correlation with job performance.

Conclusions: According to the results, political skills and job tension affected the relationship of individual’s accountability with job performance. The results put emphasis on the necessity of reassessing the mediating roles of political skills and job tension in surveying the causal relationships of accountability with job performance.

Introduction: Work-related fatigue is a source of concern, even in most industrialized countries. One of the most important factors influencing an employee’s physical and mental condition is the degree to which employees are able to recover from fatigue and stress after work. Factors such as workload can cause fatigue in workers. The aim of this study was using the need for recovery scale to assess workload in mine workers and its relationship with demographics.

Methods: In this cross-sectional study, 80 workers of a mine were surveyed. The data gathering tools used in this study were demographic characteristics questionnaire and the need for recovery scale. The scale assesses the workers workload with 11 two-optioned phrases. Mean, standard deviation, and Pearson’s correlation coefficient and ANOVA tests were used in order for data analysis.

Results: Mean (SD) score of the need for recovery scale was 55.22 (23.93), indicating moderately high workload in the workers. A total of 58.7% of workers experienced high levels of workload. Among the demographics, only body weight had a significant relationship with the need for recovery score (P value = 0.043).

Conclusions: Due to the relatively high need for recovery in the study population, solutions should be employed, such as reducing the workload, use of work-rest schedules, performing heavy tasks within teams, and providing conditions for proper and enough recovery after work, which can increase health conditions of workers.

Introduction: Driving is a complex task engaging high level of cognitive and motor processes. Adding to this complexity, engagement in cognitive secondary tasks such as talking with other passengers, speaking on the cell phone or listening to radio may effect driving performance. In addition, age-related cognitive limitations may adversely challenge driving performance. As the number of elderly drivers is rising, it is important to pay more attention to this matter.

Methods: The effects of cognitive secondary tasks on driving performance were explored through two on-road experiments (with and without listening to a recorded dialogue). In this study thirty-two individuals (male, M = 72.6, SD = 5.43) voluntarily took part in the experiments. The mean driving speed, duration of driving in unsafe-zones, numbers of overtaking, and deviation of lateral lane position were recorded, adopting a radar system and video camera. After determination of the normality of data, paired t test and correlation analysis were conducted.

Results: Mean driving speed (P < 0.05), duration of driving in an unsafe zone (P < 0.05), and numbers of overtaking (P < 0.001) showed considerable reduction of participants’ engagement in listening to the recorded dialogue. In contrast, mean deviation of lateral lane position increased.

Conclusions: The findings revealed that driving performance of elderly drivers was effected when listening to a recorded dialogue. However, in order to increase driving safety, they adopted some compensating strategies.