Assessment of Load Manual Lifting among Shelf-Stoking Workers in Chain Stores: A Cross-Sectional Study.

In Iranian stores, shelf workers, in addition to shelf-stocking, perform diverse tasks, such as working as a cashier, cleaning, barcode reading, labeling goods, and entering the price with the portable data terminal (PDT). Therefore, this study aimed to investigate the prevalence of work-related musculoskeletal symptoms (WMSs) and assess load manual lifting among shelf-stoking workers. This cross-sectional study was conducted among 101 shelf-stoking workers (60 males and 41 females) in chain stores at Shiraz city, Iran. The subjects were selected by cluster sampling from chain stores in Shiraz city, namely Refah, Canbo, Soroush, and Tirazis. Then, the required number of samples was selected and entered into the study from each cluster in proportion. The Persian version of the Nordic Musculoskeletal Questionnaire and the National Institute of Occupational Safety and Health-variable lifting index method were used to collect the required data. Data were analyzed by SPSS software version 22 using the Mann-Whitney U test, Spearman's correlation coefficient, and linear regression. Ankles/feet, lower back, and knees had the highest prevalence of WMSs among the participants. About 70.3% of workers had a VLI higher than 1. There was an association between gender and VLI. The VLI was higher in males than females. The study's findings revealed that the medians of the VLI were significantly different among participants with/without upper back symptoms during 12 months prior to the study and among participants with/without lower back symptoms during 7 days prior to the study. According to the linear regression analysis, gender and lower back symptoms during 7 days prior to the study remained in the model and were associated with the VLI. The findings revealed that the back region of the shelf-stoking workers is prone to work-related musculoskeletal disorders. In addition, based on the results, gender and lower back symptoms during the 7 days prior to the study were predicting variables for VLI. This study provides an overview of pain/discomfort and postural load in shelf-stoking workers. Since the principles of ergonomics for the placement and layout of shelves are the same in all stores, the findings of the present study can be used in other stores.

Validating the effectiveness of a self-report tool to predict unsafe behavior of industrial workers: a QEEG analysis.

Objectives. Unsafe behavior (UB) is defined as the likelihood of intentionally or unintentionally deviating from pre-defined plans. This study aims to investigate the validation of a self-report tool for measuring workers' cognitive-based UB using quantitative electroencephalography (QEEG). Methods. The cognitive-based unsafe behavior questionnaire (CUBQ) was completed by 632 front-line workers in a manufacturing industry to identify differences in the backgrounds of the subjects regarding UBs. Two groups were then selected as extreme groups and QEEG was conducted based on the international 10-20 electrode placement. Results. The mean values of absolute power (AP), alpha/beta ratio (ABR) and alpha/gamma ratio (AGR) from brain oscillations in different regions of the cortex were significantly different between the studied groups (p < 0.05). Additionally, these values were found to be significantly correlated with slips, lapses and mistakes, as measured by certain scales of the CUBQ (p < 0.05). Conclusions. The findings of this study indicated differences in brain oscillation activities among industrial workers with different UB backgrounds. These results confirm the effectiveness of CUBQ as a proactive tool for safety practitioners to predict industrial workers' UBs.

Dynamic stability evaluation of trunk accelerations during walking in blind and sighted individuals.

BACKGROUND: Dynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability. METHODS: The current study was conducted on 20 congenital blind and 10 sighted people (15-38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path. RESULTS: In the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis. CONCLUSION: Visual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

Looking beyond the screen: A systematic review of safety in control rooms.

As a complex socio-technical system, the Control Room (CR) is central to many industries, such as process, aviation, transportation, and mining. CRs' complexity impacts the safety, operational, engineering, regulatory, and financial performance of the system. In this study, a search strategy was defined and applied to three reputable databases: Scopus, Web of Science, and PubMed. The search results underwent a two-stage screening process based on inclusion and exclusion criteria. The inclusion criteria were investigating the safety in the CR, full-text availability, and writing in English. The exclusion criteria were unrelated to the safety in the CR, non-English Language, and non-original studies. A total of 59 studies were included in the analysis. The included articles were systematically reviewed from the Human Reliability Assessment (HRA) and Human Factors Engineering (HFE) perspectives. Since these records covered various subjects related to human reliability and human factor aspects, a categorization step was added to the study process. In this step, all included studies were categorized based on their subjects. A total of 7 categories were identified, including reliability (17 documents), safety performance (13 documents), decision-support systems (7 documents), fire safety (2 documents), communication/teamwork (11 documents), situation awareness (4 documents), and others (5 documents). Finally, the included studies in each category were analyzed and discussed. The results of this study help identify different aspects of safety in the control room and plan to improve their safety weaknesses, which ultimately leads to an increase in the efficiency of employees and various industries.

Assessment of the effects of white cane variables on step symmetry of blind individuals.

BACKGROUND: Step symmetry is an important feature of human gait and is often regarded as a key index of healthy individuals' walking. This study evaluated the effects of height, white cane technique, and cane tip on symmetrical gait in blind individuals. MATERIALS AND METHODS: Twenty blind and ten sighted subjects, aged 15-38 years, participated in this study. The harmonic ratio (HR) and improved HR (iHR) were measured by trunk accelerometer as gait symmetry index in three axes: anteroposterior (AP), vertical, and mediolateral of the body. These parameters were measured in the sighted group in open-eye conditions and in the blind group in five experimental conditions with different two heights (standard and long), two tips (pencil and roller), and two techniques (two-point touch and constant contact) of white cane when they walked in the 6-m path. RESULTS: There was a significant difference between HR and iHR of the blind and sighted group, which indicates a significant reduction of symmetry loss in the blind group. Among the five different conditions studied in the group of blind people, an increase was observed in the HR and the iHR on the AP axis during the application of a standard cane with a roller tip, which indicated an increase in symmetry. CONCLUSION: Based on the results, a long cane with a pencil tip and a standard cane with a roller tip in the constant contact technique can increase step symmetry.

Knee Extension Exercise Effects on Physiological and Psychophysical Performance: Normal Weight Versus Obese Office Workers.

BACKGROUND: Knee extension exercise is useful and practical for obese and overweight people as this form of exercise is effective in minimizing body weight loading on joints and improving the body's physiological function. This study aimed to compare the physiological and psychophysical parameters of office workers while computer-based working in an active workstation equipped with an active footrest (AFR) prototype with a mechanism for performing knee extension exercises in a sitting position, and also to compare the physiological and psychophysical parameters among normal-weight and obese office workers. METHODS: In this quasi-experimental study, the physiological parameters of heart rate (HR) and energy expenditure (EE) (measured with the Fitbit Charge HR smartwatch) were measured in two cross-over random sessions for 32 office workers (16 normal-weight and 16 obese) aged 28 to 50 years (M = 42.72, standard deviation [SD] = 4.37) while performing office tasks in sitting and active workstations (equipped with AFR). Perceived physical exertion, comfort, fatigue, and liking were also measured by rating the participants. FINDINGS: Short-term activity of the participants with AFR performing computer tasks significantly improved physiological and psychophysical parameters compared with the participants in sitting workstations. However, there was no significant difference in the effect of AFR on physiological and psychophysical parameters between normal-weight and obese participants. CONCLUSIONS/APPLICATION TO PRACTICE: Given the significant increase in EE and HR resulting from exercise with AFR compared with the conventional workstation, the use of AFR can help office workers achieve the minimum standard of physical activity at their workplace.

The potential impact of emotionally loaded stimuli on over/under-estimating neutral situations among power plant control-room operators.

BACKGROUND: Human emotions vary on a contextual basis. The significance of emotions becomes even more salient in Control Room Operators (CROs) in power plants. OBJECTIVE: This study investigated the effects of emotionally loaded pictures on over/underestimating neutral situations. METHODS: Twenty CROs voluntarily enrolled in the present study. Twenty-one blocks were considered, including ten emotionally loaded and 11 neutral blocks. The stimuli were alternatively submitted to subjects in random order. Each block comprised 13 images from the International Affective Picture System (IAPS), which were shown for 5 seconds. Subjects were required to complete the Self-Assessment Manikin (SAM) after exposure to the first and the last neutral blocks, which were identical. RESULTS: Our analyses showed significant differences between IAPS arousal and SAM1 and SAM2 arousal ratings (p SAM1&IAPS = 0.00, p SAM2&IAPS = 0.02). There was no significant relationship between the first and the second arousals, and emotionally loaded images corresponded to no significant difference in terms of valence. CONCLUSION: The findings suggested that the participants overestimated neutral situations compared with IAPS only in arousal level. Furthermore, CROs can still retain their ability to assess neutral situations in the case of viewing emotional stimuli, especially in valence level, at least half an hour after the first rating. A study design with pure negative/positive and high arousal levels may still provide even more significant results.

Investigating Glenohumeral Joint Contact Forces and Kinematics in Different Keyboard and Monitor Setups using Opensim.

Background: The musculoskeletal complaints of the shoulder are prevalent in people who work with computers for a long time. Objective: This study aimed to investigate the glenohumeral joint contact forces and kinematics in different keyboards and monitor setups using OpenSim. Material and Methods: Twelve randomly selected healthy males participated in an experimental study. A 3×3 factorial design was used in which three angles were considered for the monitor and three horizontal distances for the keyboard while performing standard tasks. The workstation was adjusted based on ANSI/HFES-100-2007 standard to maintain a comfortable ergonomic posture for controlling confounding variables. Qualisys motion capture system and OpenSim were used. Results: The maximum mean range of motion (ROM) of both shoulders' flexion and adduction was observed when the keyboard was 15 cm from the edge of the desk, and the monitor angle was 30°. The maximum mean ROM of both shoulders' internal rotation was recorded for the keyboard at the edge of the desk. Peak forces for most right shoulder complex muscles were obtained in two setups. 3D shoulder joint moments were significantly different among nine setups (P-value<0.05). The peak anteroposterior and mediolateral joint contact forces were recorded for the keyboard at 15 cm and the monitor at zero angles (0.751 and 0.780 N/BW, respectively). The peak vertical joint contact force was observed for the keyboard at 15 cm and the monitor at 15° (0.310 N/BW). Conclusion: The glenohumeral joint contact forces are minimum for the keyboard at 8 cm and the monitor at zero angles.

Recommended maximum holding time of common static sitting postures of office workers.

Objectives. A posture maintained for a long period can be harmful to the health of office workers. This study aimed to estimate the recommended ergonomic duration for maintaining different sitting postures. Methods. Forty healthy male and female students participated in this experiment designed to measure perceived discomfort caused by maintaining common static sitting postures of office workers in a simple ergonomic set-up for 4 min. The Borg CR10 scale was given to the participants to assess the discomfort in different body parts, before and after each experiment. Based on the mean group discomfort level of 2, the recommended holding time of each posture was estimated. Results. The recommended holding time and its discomfort score for each studied posture were tabulated. The shortest holding time of a posture was obtained for the moderate neck flexion (1.61 min), and the longest holding time was obtained for a leg posture with 90° knee flexion (6.45 min). Conclusions. The recommended holding time in this study may help to assess the risk of musculoskeletal disorders (MSDs) in office workers and train the individuals involved in office tasks in proper sitting behavior.

Development of an Ergonomic, Portable, Climber-Propelled Date Tree Climbing Device.

In the most of main date fruit producer regions, including Iran, date palm crown access operation is still performed traditionally. The date plantation workers need to climb date trees. This may cause an unsafe condition, which increases the risk of fall from height. It is also associated with ergonomic and health problems. The present study aimed to develop a date tree climber device (DTCD) covering all aspects of safety, ergonomics and efficiency. A primary model of the DTCD was structured and modified based on a review of existing devices, a field investigation and an unstructured interview with 20 farmworkers. Participants rated their comfort, perceived pain and discomfort as well as exertion levels when using the DTCD compared to a traditional device (Parband). In total, eight key elements were suggested for the desired device. More than 60% of the participants reported that the DTCD was comfortable/very comfortable compared to Parband. Additionally, DTCD could significantly reduce the pain and discomfort of the back (p < .001), knees (p = .001) and Ankles/feet (p = .01). However, no significant difference was found between devices when the physical exertion was compared through Borg's RPE scale and heart rate analysis. The results of regression analysis showed that the DTCD users perceived lower exertion as the body weight increased (ß = -0.18, p = .013). The signs of musculoskeletal disorders, pain and discomfort were strongly reduced among DTCD users and safety aspects improved, generally by reducing discomfort and physical exertion.

Employing a three-stage procedure to develop a sizing system for medical gloves.

There is a need for gloves that are designed based on the dimensions of the hand of each society because the proper size is a key factor that affects performance. This study aimed to design and develop a glove-sizing system for Iranian healthcare workers using anthropometric data. This study was conducted on a sample including 540 healthcare workers across Iran classified by ethnicity and gender. Thirty-three dimensions were measured as the anthropometric data. Principal Component Analysis (PCA) and clustering analysis were used to create classifications for glove sizes. The most effective dimensions in defining the hand sizes of Iranian healthcare workers were middle finger length and the handbreadth. The designed six-size system covered 94% of the sample. This system can be used to design suitable gloves for Iranians. The sizes presented can be used to compare size differences in different communities. Practitioner summary: In this study, an attempt was made to design a sizing system with maximum coverage for medical gloves using statistical analysis methods and hand anthropometric dimensions of Iranian healthcare workers. The method of this study can be used in other communities as well for improving sizing systems.Abbreviations: PCA: Principal Component Analysis; GSS: Glove Sizing Systems; TEM: Technical error of measurement; R: Reliability coefficient; KMO: The Kaiser-Meyer-Olkin; PC1: The first principal component; PC2: The second principal component; FCMC: Fuzzy c-means clustering; XS: Very small; S: Small; SM: Medium small; LM: Medium large; L: Large; Xl: Very large.

Developing a Decision Aid Tool for selecting pen-paper observational ergonomics techniques: a quasi-experimental study.

BACKGROUND: A significant error that may occur during ergonomic risk assessment and invalidate assessment reliability corresponds to technique selection. This study aimed to develop a new tool called the Decision Aid Tool (DAT) to reduce pen-paper observational technique selection errors. METHODS: This quasi-experiment before-after study was performed in three phases. In the first phase, the participants' skills in technique selection were examined by showing them 20 videos of different single-task jobs. In the second phase, the DAT was designed using pen-paper observational techniques. Finally, in the third phase, 115 occupational health specialists included in the study through purposive sampling of experts evaluated the tool's efficacy. RESULTS: The results of the first phase showed that 62% of participants made an error in selecting the proper technique. The mean and standard deviation scores from the first and third phases were 11.4 ± 6.59 and 39.01 ±1.89, respectively. The mean scores increased significantly after using DAT, and 97.5% of participants could correctly select task techniques. CONCLUSIONS: The efficacy of DAT was confirmed in a quasi-experimental before-and-after study. Using DAT increases the participants' ability to choose the correct technique. The DAT can be functional for practitioners to select the pen-paper observational techniques correctly under the purpose of assessment, the body areas, and the characteristics of the task to be assessed.

A Mixed-Methods Investigation of Occupational Health Specialists' Knowledge and Application of Pen-and-Paper Observational Methods for Ergonomics Assessment.

OCCUPATIONAL APPLICATIONSErgonomic risk assessment is a key step in managing work-related musculoskeletal disorders. Diverse assessment methods exist, and errors may occur if inappropriate methods are selected. Understanding the level of knowledge, how to use methods, and exploring factors affecting erroneous usage of these methods, can provide useful information for health and safety regulatory authorities and decision-makers to identify problems and determine an action plan to eliminate them. We found that Iranian occupational health specialists have little knowledge about the types of pen-and-paper observational methods (OMs), and most of them use a limited number of these methods. Content analysis of interviews identified three main categories of influential factors and 12 subcategories. The main categories were educational, individual, and organizational factors. These results suggest the need for more effort to ensure that practitioners possess better knowledge and skills in the selection and application of pen-and-paper OMs.

Background Ergonomic risk assessment is a key step in managing ergonomics in the workplace. Errors in selecting risk assessment methods may occur during risk assessment and could invalidate the reliability of the results obtained.Purpose The aims of the present study were to investigate Iranian occupational health specialists' knowledge and application of pen-and-paper observational methods (OMs) for ergonomics assessment and to determine their influential factors.Methods We used a mixed-method design in two phases, combining quantitative and qualitative approaches. Quantitative data were collected from 237 occupational health specialists who were included in the study through purposive sampling of experts. In the qualitative phase, in-depth semi-structured interviews were conducted with participants from the first phase, and the factors associated with the selection and application of the pen-and-paper OMs were examined over a 6-month period.Results Participants were familiar with 13 out of 34 methods studied, and they had performed risk assessments with only nine of them. The most frequently used methods were RULA (95.4%), REBA (84.8%), QEC (65.4%), and ROSA (54.9%). Content analysis of interviews identified three main categories of influential factors and 12 subcategories. The main categories included educational, individual, and organizational factors.Conclusion Iranian occupational health specialists were found to have relatively limited knowledge about pen-and-paper OMs, and most of them use a limited number of these methods. These results suggest the need for more effort to ensure that practitioners possess better knowledge and skills in the selection and application of these methods. Creating stricter regulations regarding the qualifications of practitioners, modifying academic curriculum content, continuously monitoring the performance of practitioners, and holding retraining workshops in a purposeful manner could help minimize errors in selecting and applying pen-and-paper OMs.

Physical and psychological workloads and their association with occupational fatigue among hospital service personnel.

BACKGROUND: Physical and psychological workloads are a vital issue in the workplace. This study aimed to investigate the association between physical and psychological workloads and occupational fatigue among Iranian hospital service personnel. In Iran, hospital service personnel refers to a group of healthcare workers who undertake a range of duties, such as moving and carrying the hospital waste, transporting patients by wheelchair or gurney to the operating room, x-ray department, other wards, or other locations around the facility, performing cleaning tasks such as changing linens, mopping floors, and sterilizing equipment, and following infection control procedures to reduce the risk of spreading germs within the hospital setting. METHODS: This cross-sectional study was conducted on 198 Iranian hospital service personnel. The response rate was 86%. The data were gathered using 1) The Persian version of the Job Content Questionnaire (P-JCQ) for assessing physical and psychosocial workloads and 2) The Persian version of the Swedish Occupational Fatigue Inventory (P-SOFI-20) for assessing fatigue dimensions. RESULTS: According to the P-JCQ, the physical and psychological workload intensities were high in 72.7% and 47% of the participants, respectively. Based on the P-SOFI, the participants' mean scores of "physical fatigue" (21.73 ± 6.2), "psychological fatigue" (13.61 ± 5.76), and "fatigue due to shift work" (18.17 ± 5.6) were moderate, while the mean score of "general fatigue" was high (27.3 ± 6.98). The findings revealed that various types of fatigue are associated with age, gender, marital status, daily working hours, and psychological workload. CONCLUSIONS: Psychological workload was a determinant of occupational fatigue among Iranian hospital service personnel. Hence, an interventional program, including job enrichment, job rotation, and work-rest cycle, is recommended.

Adverse Effects of Sit and Stand Workstations on the Health Outcomes of Assembly Line Workers: A Cross-sectional Study.

Introduction: Sitting and standing workstations can affect individual's health outcomes differently. This study aimed to assess the effects of sit and stand workstations on energy expenditure and blood parameters, including glucose and triglyceride, musculoskeletal symptoms/pain and discomfort, fatigue, and productivity among workers of assembly line of a belt factory. Methods: This cross-sectional study was conducted on 47 male assembly line workers (24 workers in sitting workstation and 23 workers in standing workstation) with at least one year of working experience. Data were gathered via demographic/occupational characteristics, Fitbit system, medical records, the Persian version of the Nordic Musculoskeletal Questionnaire (P-NMQ), the Persian version of the Numeric Rating Scale (P-NRS), the Persian version of the Swedish Occupational Fatigue (P-SOFI), and Persian version of the Health and Work Questionnaire (P-HWQ). Results: The results showed that there were no statistically significant between the demographic/occupational details of the participants in sitting and standing groups, except work experience. The findings of the present study revealed that the energy expenditure, and blood glucose/triglyceride there are not statistically differences between sitting and standing groups. In addition, the prevalence of musculoskeletal symptoms in the neck, lower back, knees, and ankles/feet in standing group was significantly higher than the sitting group. The means of severity of discomfort/pain in all body regions were significantly higher in standing group compared to other group. Generally, occupational fatigue was higher among the standing group compared to sitting group. About productivity, the 'concentration/focus' and 'impatience/irritability' subscales in sitting group were higher than the standing group. Contrariwise, other subscales of the productivity, including 'productivity', 'supervisor relations', 'non-work satisfaction', 'work satisfaction' in the standing group were higher than the sitting group. Conclusions: To reduce the adverse effects of sitting and standing workstations on individual's health outcomes, planning to use sit-stand workstations is recommended.

Psychometric properties of the physical environment problems and barriers scale in older adults' homes using an ergonomic approach.

BACKGROUND: As older adults prefer to live in their homes, it is of paramount importance to examine the adaptation of the environment to the older adults' capabilities. OBJECTIVE: The aim of this study was to develop and evaluate psychometric properties of a scale to measure physical environment problems and barriers in older adults' homes using an ergonomic approach in Iran. METHODS: This mixed-method investigation was conducted in two stages in Yazd, Iran. The primary 71-item version of the questionnaire was developed according to qualitative findings and a thorough review of the literature. Then the psychometric characteristics, including face, content, construct validity, were assessed. Content validity was also assessed using CVI and CVR. Finally, its reliability and construct validity were confirmed by composite reliability (CR), Fornell-Larker matrix, and confirmatory factor analysis (CFA) using Smart PLS software version 3. RESULTS: The face validity of the developed scale was acceptable, and the mean scores of CVI and CVR were 0.78 and 0.84, respectively. The preliminary draft of the scale was categorized into seven dimensions. Factor validity and reliability were confirmed by acceptable factor loadings, and desirable realms of composite reliability (>0.7) average variance extracted (>0.5). The cross-loading method and the Fornell-Larker matrix were used to evaluate the divergent validity of the scale, and the results confirmed its acceptable fit. CONCLUSIONS: The findings indicated that reliability reached acceptable values, and different aspects of validity were almost confirmed. Accordingly, the questionnaire was to measure physical environment problems and barriers in older adults' homes; however, it requires further validation for future use in other contexts.

Validity and reliability of Persian version of the workplace cognitive failures scale and its relationship with personality traits.

BACKGROUND: In nursing practice, cognitive failures can be evaluated as an essential indicator of the cognitive capacity of individuals. OBJECTIVES: This study aimed to determine the validity and reliability of the Persian version of the Workplace Cognitive Failures Scale (P-WCFS) among Iranian nurses and its relationship with personality traits. METHODS: Data collection had two phases: 1) The P-WCFS prepared through a standard translation process. Then the content validity was evaluated by a panel of specialists. Reliability Cronbach's coefficient alpha obtained 0.91 from a pilot study. 2) For measuring neuroticism and conscientiousness used the Goldberg Personality Questionnaire. Exploratory and confirmatory factors analyzed in two separate parts of the sample (n = 351). SPSS (v 18) and STATA 14 performed for Statistical analysis. Spearman correlation and Pearson correlation coefficient used to measuring the convergence and examine the relationship between the subscales of the questionnaire. RESULTS: Cronbach's alpha was 0.92, which showed a high level of reliability for this questionnaire. The three-factor model of WCFS was well-fitted. The reliability of all three sub-scales was a reasonable level. Cognitive failures and its subscales had negative and strong relationships with conscientiousness and neuroticism. The highest internal consistency was related to memory subscale, and all scales had a success rate of 100%. CONCLUSIONS: This study showed the P-WCFS has high reliability and validity and can be used in nursing society.

Comparison of physical workload and physical work capacity among municipality cleaners in Shiraz to determine number of workers needed to counterbalance physical workload.

BACKGROUND: Assessing physical workload is the most important step in deciding whether a workload is high and adopting appropriate control strategies to reduce physical workload. This study aimed to compare physical workload and Physical Work Capacity (PWC) among municipality cleaners in Shiraz to determine the number of workers needed to counterbalance physical workload. METHODS: The present cross-sectional study was performed on 97 municipality cleaners in Shiraz. In the first step, the participants' maximum aerobic capacity (VO2-max) was estimated in the laboratory using an ergometer bicycle and the Young Men's Christian Association (YMCA) protocol, based on which the PWC was estimated. Secondly, energy expenditure and heart rate during work were measured using a POLAR400 device in an eight-hour shift. At the end of the work shift, the workers' perceived physical exertion was assessed using a Rating of Perceived Exertion 6-20 (RPE 6-20) Borg scale. In the final stage, the physical workload was assessed based on the results of the two steps. RESULTS: The mean VO2-max of the cleaners and PWC were estimated to be 2.6 ± 0.66 l min-1 and 4.3 ± 1.088 kcal min-1, respectively. The average energy consumed during work was 4.122 ± 1.016 kcal min-1. The overall results of this study showed that physical workload was greater than PWC in 46% of the municipality cleaners. In addition, it was found that 12.45% workforce was required to be added to the street cleaners of Shiraz municipality to reduce the physiological workload on the employed workforce. CONCLUSIONS: With respect to the high level of physical activity in a significant proportion of the cleaners, measures such as increasing the workforce are suggested.

Investigating the Effect of Keyboard Distance on the Posture and 3D Moments of Wrist and Elbow Joints among Males Using OpenSim.

Musculoskeletal disorders (MSDs) of the upper extremities and computer use are common in modern societies, and both show a growing trend. This study was conducted to determine the posture and 3D moments of wrist and elbow joints at different keyboard distances on a desk. Twelve healthy right-handed male volunteers attended the motion analysis laboratory. A keyboard was placed at three different distances from the participants' bodies while performing a standard computer task. The workstation was adjusted according to ANSI/HFES-100-2007 standard for each participant to maintain a comfortable ergonomic posture for controlling confounding variables. Qualisys motion capture system, OpenSim (Ver. 4.1), and visual analog scale were used to collect and analyze the data. The highest levels of wrist flexion and radial deviation as well as elbow flexion and pronation were observed when the keyboard was at the edge of the desk. When the keyboard was 8 cm away from the edge of the desk, the right wrist flexion and radial deviation decreased 83% and 89%, respectively. In the left wrist, flexion and radial deviation decreased 94%. With increasing the distance of the keyboard from the edge of the desk, the right elbow flexion, pronation, and left elbow flexion decreased, 95%, 76%, and 85%, respectively. No significant difference was found for the left elbow pronation, wrist, and elbow joint moments, in the studied keyboard distances. However, a cut-off point has to be specified because large keyboard distances cause high extension and flexion of the limbs. The keyboard position relative to the body is an important parameter in computer work and has a significant impact on the posture of the upper extremities. A keyboard should be located at a distance that allows the upper extremities to remain in a neutral position so that the risk of MSDs is reduced.

Effects of an ergonomic intervention program based on the PRECEDE-PROCEED model for reducing work-related health problems and exposure risks among emergency medical dispatchers.

OBJECTIVE: To evaluate the effectiveness of an ergonomic intervention program based on the PRECEDE-PROCEED model in terms of improving exposure risks and work-related health problems in emergency medical dispatchers. METHODS: This quasi-experimental study used an interrupted time series design. Participants were 55 employees working in an Emergency Medical Communications Center in Iran. The intervention program was based on the PRECEDE-PROCEED model and included five face-to-face training sessions and installing auxiliary equipment according to best ergonomic principles. Direct observations of the emergency medical dispatchers' working postures using the Rapid Office Strain Assessment and a survey which included a modified Nordic Questionnaire, Work Ability Score, Visual Fatigue Questionnaire, and a Behavioral Factors Questionnaire were used at three time points: baseline, 1 month post-intervention, and 3 months post-intervention. RESULTS: The modified Nordic Questionnaire showed significant reductions in pain intensity scores for neck, lower back, knee and ankle after the ergonomic intervention program. In addition, there were considerable post-training improvements in behavioral factors (knowledge and enabling factors) and working postures. No significant changes were observed in Work Ability Scores, or visual symptoms. CONCLUSIONS: An ergonomic intervention program based on a systematic framework such as the PRECEDE-PROCEED model and on-site interventions can be effective in improving and enhancing the working conditions of emergency medical dispatchers. Therefore, it is suggested that ergonomic interventions be implemented based on standard and valid behavioral change models such as PRECEDE-PROCEED model in other work environments in which musculoskeletal pain and digital eye strain are common.