Journal of Health and Safety at Work

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Introduction: Many general indicators have been proposed to assess an organization’s safety performance. However, due to their holistic nature, these indicators may not always reflect safety-specific aspects of an organization’s performance. In other words, the nature of an organization’s activities necessitates the use of specific criteria to better reflect safety performance. This study aimed to identify and measure key safety performance indicators using the Delphi method in Alborz Province Electric Power Distribution Company.
Material and Methods: This descriptive, survey-based study utilized the Delphi method to collect the opinions of 11 safety experts in the electric power distribution industry. Opinions were gathered in four phases, and key indicators were determined in the last phase of the study. These indicators were subsequently used to evaluate the safety performance of Alborz Electric Power Distribution Company for three months.
Results: This study identified and documented 34 safety activities. The expert group proposed 20 indicators in the first phase of the Delphi method. In the second and third phases, four and one indicators were eliminated, respectively, because they did not receive the required score. The content validity ratio (CVR) and content validity index (CVI) were calculated for the remaining 15 indices in the fourth phase. The results revealed that the mean quarterly performance scores of Alborz Province electric power distribution districts and departments in 2016, including Nazarabad, Savojbolagh, Mehrshahr, Fardis, West, East, Taleghan, and Eshtehard, were 78.9, 54.7, 78.8, 75.9, 75.7, 80.8, 61, and 83.5 out of 100 points, respectively.
Conclusion: The Delphi method is useful for identifying key safety performance indicators. The indicators discovered using this technique are active indicators (pre-accident) that are crucial in determining Alborz Electric Power Distribution Company’s safety performance. These indicators are suggested for use in evaluating the safety performance of other electric power distribution companies.

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Introduction: In many occupations, users must sit for prolonged periods during their job activities. Prolonged sitting is associated with fatigue, leading to postural changes that can increase spinal loads. Despite the importance of this topic in terms of the extent of prolonged sitting and its subsequent adverse consequences, little attention has been given to this occupational activity. Hence, this study investigates changes in neck, trunk, and muscle activities and fatigue levels in prolonged sitting computer tasks.
Material and Methods: Twenty healthy subjects (gender-balanced) from the student community with at least five years of experience in computer work aged between 20-30 years were asked to randomly perform three types of computer tasks for 90 minutes (each task for 30 minutes). Electromyographic (EMG) activities of right and left cervical (ESCR and ESCL), thoracic (ESTR and ESTL), and lumbar (ESLR and ESLL) erector spine and upper trapezius (UTR and UTL) muscles were continuously recorded. Root mean square (RMS) and median frequency were extracted as EMG metrics. Subjects also rated their perceived discomfort using a Visual Analogue Scale (VAS). The effect of time, gender, and their interaction on muscle EMG activities, fatigue, and discomfort were explored.
Results: Time had a statistically significant effect on UTR, ESCR, and ESTR muscle activities. UTL and ESCR muscle activities significantly differed between male and female subjects. Further, the findings confirmed the interactive effect of time and gender on ESTR muscle activity. UTR, ESCR, ESCL, ESTL, and ESLL muscles’ fatigue index changed statistically over time.
Conclusion: The findings confirmed neck and trunk muscles’ fatigue by increasing muscular activity and reducing frequency contents over time, per the subjective rating of discomfort.

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Introduction: Prolonged sitting postures are among the risk factors for musculoskeletal disorders in occupational settings, leading to increased musculoskeletal discomfort in various body regions. This discomfort can negatively impact individuals’ health and impose high costs on society in terms of work absences, early disabilities, and reduced productivity. The purpose of this study is to investigate the effect of stretching exercises on the level of discomfort, muscle activity, and muscle fatigue in the neck and trunk region during prolonged sitting tasks.
Material and Methods: This experimental study was conducted among 20 healthy male and female participants under two test conditions: control and intervention. In the control condition, participants performed cognitive tasks (watching videos, typing, text editing, and nback cognitive test) without any intervention. In the intervention condition, participants performed stretching exercises before each task. The Visual Analogue Scale was used to assess perceived discomfort. Also, muscle fatigue was evaluated using an electromyography (EMG) device and RMS and MPF measures.
Results: Discomfort in hands and arms (p-value=0.04) and lower back (p-value=0.03) during video-watching was higher in the control condition than in the intervention. Regarding muscle activity, the activity of the right cervical erector spinae during the video-watching task was lower in the control condition than in the intervention. In the n-back cognitive test and text editing, the right lumbar erector spinae muscle activity was significantly higher in the control condition than in the stretching exercises intervention. Regarding the left cervical erector spinae, a significant difference was observed between fatigue in control and intervention conditions during the video-watching task. Also, right thoracic erector spinae fatigue in text editing was higher in the control condition than in the exercise intervention; however, for the n-back test, the level of fatigue was lower in the control condition compared to the intervention.
Conclusion: The perceived discomfort in seated computer tasks is generally lower in the exercise intervention compared to the control condition. The stretching exercises used in this study improved muscle activity and reduced fatigue in some of the trunk muscles, although the effects of the exercises depend on the type of task. Overall, muscle fatigue in two cognitive tasks, text editing and n-back, was more affected by stretching exercises than other tasks.

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Introduction: Many industries have multiple factors harmful to health, leading to simultaneous exposure of these factors to each other. Noise is one of the most common physical parameters in the work environment. On the other hand, heat is also increasing due to various energy processes in industries. Therefore, this study was conducted with the aim of determining changes in physiological parameters and visual-auditory attention in acute exposure to heat and noise.
Material and Methods: In this experimental study, 72 individuals (36 men and 36 women) aged between 23 and 33 years participated according to the inclusion criteria. In total, 12 different test modes were performed (3 temperature levels and 4 noise pressure levels). The test was conducted for each person in 4 steps during a specific day. The duration of exposure to each condition was half an hour, and a half-hour rest was given between each test condition. Saliva samples of each subject were collected before and immediately after exposure to noise and heat. Also, The Integrated Visual and Auditory (IVA) was recorded by the participants simultaneously.
Results: The results of combined exposure to noise and heat on visual and auditory attention showed that only two modes of combined exposure, SPL95+WBGT34 and SPL95+WBGT29, caused a significant increase (P < 0.05) in mental workload and a significant decrease (P < 0.05) in visual and auditory attention. In addition, the results showed that independent exposure to noise at the levels of 85 and 95 dB and exposure to heat at higher temperature levels of 34 and 29 degrees Celsius cause a significant increase (P < 0.05) in salivary cortisol after exposure. The results of the effect of combined exposure to noise and heat on salivary cortisol showed that three experimental modes of combined exposure (SPL85+WBGT34, SPL95+WBGT29, and SPL95+WBGT34) caused a noticeable and significant (P<0.001) increase in salivary cortisol.
Conclusion: Indeed, salivary cortisol can be recommended as a physiological index to evaluate noise and heat exposure. It’s also noteworthy that salivary cortisol is more affected by noise and heat exposure than cognitive performance.

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Introduction: Studies have demonstrated that teaching carries a substantial burden of health risks. Prevalent health issues among teachers include asthma, respiratory diseases, musculoskeletal problems, and mental disorders. These problems can be attributed to the specific attributes of their work environment. Consequently, this study aims to investigate the correlation between air quality within educational establishments and the overall health of teachers.
Material and Methods: This systematic review aims to examine the impact of temperature, humidity, and ventilation rates within educational environments on teachers’ health status and thermal comfort. Relevant studies were searched for using the PubMed and Web of Science databases, employing keywords such as teacher, temperature, humidity, ventilation, school, classroom, health symptoms, and thermal comfort (2000-2022). The inclusion criterion was that articles examined teachers’ health and comfort with temperature, relative humidity, and ventilation of the educational place.
Results: Out of the 103 articles found in the initial search, 13 articles were finally reviewed. Six studies investigated the voice abnormalities of teachers due to various factors (including temperature, relative humidity, and the ventilation rate of the educational place) and found that these abnormalities were affected by these factors. Two studies explored the relationship between the prevalence and exacerbation of respiratory symptoms and quality parameters of the indoor environment of educational places. Additionally, five studies investigated the relationship of air quality parameters of educational places with common non-specific symptoms among teachers.
Conclusion: Teachers frequently experience symptoms such as voice disorders, respiratory difficulties, allergies, and other nonspecific ailments, which may be associated with the quality parameters of the indoor environment in educational settings. These parameters include temperature, humidity, and ventilation rate. Consequently, controlling and regulating these parameters within the recommended values can help prevent the onset or exacerbation of these symptoms.

 

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Introduction: Musculoskeletal disorders (MSDs) have a multifactorial nature. Biomechanical factors are one of the most important factors. Consequently, the precise identification of effective factors plays a significant role in controlling and preventing these disorders. Therefore, the current study aimed to identify the awkward upper body postures and their effect on the prevalence of MSDs in office workers in both women and men groups by objective methods.
Material and Methods: In this cross-sectional study, the participants were 36 office workers (18 women and 18 men). The prevalence of musculoskeletal discomfort was evaluated using the Nordic questionnaire. The upper limbs posture, including the back, neck, and wrists, was evaluated continuously with an electronic inclinometer and an electrogoniometer for 30 min, followed by analyzing the collected data.
Results: The results revealed that the highest prevalence of musculoskeletal symptoms in both gender groups was in the neck (58.33%), trunk (52.77%), and wrist (47.22%), respectively. The results disclosed that the median trunk and neck flexion in both groups is over 20° and the posture angle in women is higher than that of men (P<0.05). The results showed that pain and discomfort in the trunk and neck in both gender groups have a significant relationship with the median posture angle (P<0.05). Also, the wrist posture in both gender groups during work was in extension and static condition.
Conclusion: Based on the results of this study, the prevalence of disorders in women was higher than in men. Although the tasks performed in both groups were similar, the assessment of postures disclosed that women office workers had more awkward postures in the trunk and neck than men. In both groups, the prevalence of musculoskeletal discomfort had a significant relationship with awkward postures in the trunk and neck. According to the results of the current study, ergonomic interventions are recommended to reduce awkward postures and to prevent MSDs, particularly among women office workers.

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Introduction: Work-related musculoskeletal disorders (WMSDs) are a prevalent occupational health concern, influenced by both physical and psychosocial factors. Valid questionnaires offer a cost-effective and efficient means of evaluating WMSDs. This study aimed to validate the Persian version of the MDRF questionnaire, assess its applicability in Iran, and investigate the prevalence of WMSDs among employees in an automotive industry.
Material and Methods: This descriptive cross-sectional study was conducted among 100 employees (50 production line workers and 50 office workers) in Kerman province. The linguistic validity of the questionnaire and its translation were ensured using the Backward-Forward method. Content validity was assessed through CVI and CVR indexes. To evaluate the questionnaire’s reliability and agreement, Cronbach’s alpha and ICC were employed. User responses from the first and second series of the questionnaires were validated using Kappa and Spearman’s tests.
Results: Results indicated high reliability which was achieved by Cronbach’s alpha and ICC values of 0.960 and 0.925, respectively. The questionnaire’s validity was acceptable based on CVR and CVI tests. The prevalence of WMSDs was the highest in the lower back for both production line and office workers over the past year. The job satisfaction factor exhibited the highest risk level among the questionnaire’s four subgroups. Approximately 85% of participants were classified as having a high or very high-risk level, reflecting concerning conditions among the employees. The prevalence of WMSDs in different body parts significantly correlated with all physical and psychosocial stress factors.
Conclusion: This research highlights the influence of diverse physical and psychosocial risk factors on the occurrence of WMSDs among both occupational workers and office employees. Also, the MDRF questionnaire, whose high applicability in assessing the WMSDs risk factors was proven in this study, is an effective tool for prioritizing, planning, and executing educational and preventive measures within the workforce community to mitigate and prevent WMSDs. 

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Introduction: Due to the lack of an instrument for measuring the career issues of those with bipolar disorder, the present study was conducted to develop and examine the psychometric characteristics of the Career Issues Inventory for Persons with Bipolar Disorder (CII-BD).
Material and Methods: To check the diagnostic validity, via purposive sampling and interviews by a psychiatrist, 108 people were selected from two sample groups (53 normal people and 55 participants with bipolar disorder). The items were extracted from three sources including scientific articles related to the career issues of bipolar people, interviews with individuals with bipolar disorder, and interviews with experts using the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) systematic qualitative method. Finally, the items of the CII-BD were reduced to 81 questions. Content, construct, and convergent validity plus factor analysis of CII-BD were also examined. The reliability of CII-BD was evaluated by internal consistency and test-retest method with seven weeks intervals after the initial implementation of the CII-BD.
Results: The convergent validity of the sum score of CII-BD with the sum score of the symptom inventory of people with bipolar disorder among the sample of normal people and the sample of persons with bipolar disorder was (r=0.79, P<0.01, N=53) and (r=0.78, P<0.0001, N=53) respectively. In construct validity examination, nine subscales were extracted using the factor analysis method with varimax rotation, which included communication problems, poor work performance, insecurity, grandiosity, unreliability, change-seeking, vulnerability, lack of boundaries, and lack of self-control towards the opposite sex. In the reliability analysis, Cronbach’s alpha coefficient was 0.96 (N=55, participants with bipolar disorder) and 0.86 (N=53, normal people), respectively, P<0.05, showing the high internal consistency of CII-BD. The test-retest correlation coefficient of the sum scores of the CII-BD was r = 0.91, P < 0.01, which indicated the credible stability of the CII-BD.
Conclusion: The CII-BD is a valid and reliable instrument to measure the specific career issues of bipolar persons and their early vocational rehabilitation. It is suggested that future research should focus on choosing a job and job placement for bipolar disorder persons.

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Introduction: Due to the increase in the provision of electronic services to citizens in government offices, the number of computer users and the occurrence of musculoskeletal disorders have increased. Therefore, this study aimed to predict and model the complex relationships between the risk factors of musculoskeletal disorders in computer users working in government offices by an artificial neural network.
Material and Methods: The current cross-sectional study was conducted in 2020 on 342 employees of various government offices in Saveh city. First, the researcher visited the work environment to identify the problems and measure the environmental factors. Then, ergonomic risk assessment and psychosocial factors were evaluated using the Nordic questionnaire and the ROSA method. The effect of various factors in causing musculoskeletal disorders was investigated using a logistic regression test.Then the resulting data were collected and modeled by one of the neural network algorithms. Finally, artificial neural networks presented an optimal model to predict the risk of musculoskeletal disorders.
Results: The results showed that by increasing the level of social interactions, the level of demand, control, and leadership in the job, musculoskeletal disorders in men and women decrease. There was a significant relationship between the prevalence of musculoskeletal disorders and job demand, job control levels, social interaction levels, leadership levels, organizational climate levels, job satisfaction levels, and stress levels, in addition between reports of pain in the neck and shoulder and wrist/hand region. There was a significant relationship with the overall ROSA score. Also, there was a significant relationship between the report of pain or discomfort in the neck area with the phone screen risk score, wrist/hand with the keyboard-mouse risk score, and shoulder, upper back, elbow, and lower back with the chair risk score. The accuracy of the presented model for predicting musculoskeletal disorders was also about 88.5%, which indicates the acceptability of the results.
Conclusion: The results showed that several factors play a role in causing musculoskeletal disorders, which include individual, environmental, psychosocial, and workstation factors. Therefore, in the design of an ergonomic workstation, the effects of the mentioned factors should be investigated. Also, predicting the effectiveness of each of the mentioned factors using an artificial neural network showed that this type of modeling can be used to prevent musculoskeletal disorders or other multifactorial disorders.

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Introduction: The prevalence of COVID-19 has significantly impacted work environments and the workforce. Therefore, identifying the most important preventive and control strategies, as well as assessing their effectiveness, is of paramount importance. Various studies have shown that machine learning algorithms can be used to predict complex and nonlinear issues, including predicting the behavior of various diseases such as COVID-19 and the parameters affecting it, and can be beneficial. The purpose of this study has been to examine the importance of preventive measures and hygiene behaviors in preventing COVID-19 in the oil refining industry using various machine learning models.
Material and Methods: For this purpose, demographic information and health behaviors of individuals were collected. Subsequently, a multi-layer perceptron (MLP), radial basis function (RBF), and support vector machine (SVM) models were compared to enhance the analysis of the effects of preventive measures on COVID-19 infection. Finally, the most influential factors affecting the likelihood of COVID-19 infection were determined using sensitivity analysis.
Results: The results showed that the accuracies achieved in predicting the impact of preventive measures and health behaviors on COVID-19 in occupational settings were 78.1%, 81.2%, and 78.1% by MLP, RBF, and SVM respectively. The RBF model was identified as the most accurate model for predicting the impact of health behaviors on COVID-19 disease Additionally, the level of social distancing with customers, handwashing frequency and disinfection, the availability of cleansing and disinfecting agents for hands and surfaces in the workplace, and gatherings for eating meals and snacks were identified as the most significant health behaviors influencing the prevalence of COVID-19 in the workplace.
Conclusion: Studies of this nature can underscore the importance of attention to preventive measures and health behaviors in unprecedented circumstances. Furthermore, the utilization of artificial intelligence models and tools such as DSS (Decision Support Systems) can serve as powerful tools for optimizing control measures in work environments.
 

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Introduction: Acceptance of Health, Safety, and Environment (HSE) rules plays a crucial role in determining the performance of employees in HSE-related areas at the workplace. This study aimed to design a questionnaire to investigate influential factors on acceptance of HSE rules among employees.
Material and Methods: The face validity of the survey was assessed by ten individuals from the target population, while content validity was evaluated by ten HSE experts using both quantitative and qualitative methods. The impact scores were calculated for the quantitative assessment of face validity, and the Content Validity Ratio (CVR) and Content Validity Index (CVI) values were used to assess content validity. Construct validity was determined through Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) involving 506 participants. The reliability of the survey was evaluated using Cronbach’s alpha and the Intraclass Correlation Coefficient (ICC).
Results: All items in the survey showed satisfactory levels of impact score (>1.5), CVR (>0.69), and CVI (>0.79). The mean values for the Impact score, CVI, CVR, and S-CVI-UA were 4.26, 0.963, 0.944, and 0.62, respectively. The survey and its dimensions demonstrated strong reliability, as indicated by Cronbach’s alpha and ICC values exceeding 0.70. Additionally, EFA successfully identified the structure of the questionnaire, and CFA confirmed its goodness of fit.
Conclusion: The Persian version of the questionnaire demonstrated satisfactory validity and reliability. This instrument can be effectively used to assess the factors that influence the acceptance of HSE rules among employees in various workplace settings.

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Introduction: Lifting loads in awkward postures is a main cause of low back musculoskeletal disorders. In this context, researchers have used various indicators to determine the relationship between biomechanical variables and the risk of these disorders. This study aimed to investigate the correlation between plantar pressure distribution and the values of UTAH back-compressive forces (BCF) and lifting index (LI) during symmetrical load-lifting tasks.
Material and Methods: Thirteen healthy men, aged 25 to 35, took part in this study. The participants were instructed to symmetrically lift loads weighing 7.5 kg and 15 kg in 15 different postures, considering three horizontal distances (A, B, C) and five different heights (1-5). Pressure on the foot soles was recorded using 16 force-sensitive resistors (FSR) corresponding to eight anatomical areas on each foot. The BCF and LI were also calculated using the UTAH method and the NIOSH equation, respectively. Statistical analysis was performed using SPSS (version 21) software.
Results: Based on the results, when the load was closest to the body (A1-A5), the highest pressure was recorded in the heel and the 4th and 5th metatarsal of both feet. In lifting a load of 15 kg in the A2, B1, B2, C1, C2 postures and lifting a load of 7.5 kg in the C2 posture, the average BCF exceeded 700 pounds. The LI was greater than 1 for specific postures (B1, B2, B4, B5, C1-C5) at 15 kg and (C1, C2, C4, C5) at 7.5 kg load-lifting. During the 7.5 kg and 15 kg load-lifting, there was a significant correlation between the plantar pressure and the values of LI and UTAH (p-values < 0.05) in most postures.
Conclusion: The results showed a significant correlation between plantar pressure distribution and load-lifting postures. The study findings, which identify risk levels associated with lifting postures, lay the groundwork for future research aimed at categorizing safe and unsafe plantar pressure patterns.

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Introduction: Protection of the respiratory system has been a vital, and for this purpose, various solutions have been proposed, including the use of masks. One of the most important parameters to measure the effectiveness of the mask against the penetration of microbial agents. The present study was conducted with the aim of evaluating the bacterial and particle filtration of medical masks.
Material and Methods: To assess bacterial performance, the national standard 6138, compliant with EN14683, and Type I medical masks were utilized. Staphylococcus aureus bacterial suspension was prepared and passed through the mask using a nebulizer and through an impactor with a flow rate of 28.3 l/min. Plates containing soy agar were placed in the impactor. Subsequently, all plates were incubated, and the bacterial filtration efficiency (BFE) of the masks was determined by counting the bacterial colonies that passed through the mask’s media as a percentage of the total bacteria. It is worth noting that the pressure drop and particle filtration efficiency were also determined for all masks
Results: Based on the results of the particle removal performance for the particle size of 3 µ, the masks were categorized into three groups with efficiency above 99%, above 95% and 90%. According to the standard, all masks had an acceptable pressure drop below 40 Pa. The acceptable bacterial filtration rate for type I masks should be above 95%. The results showed that type A and B masks have an acceptable bacterial filtration rate and there is a significant correlation between the types of masks examined in terms of bacterial and particle efficiency.
Conclusion: The results showed that different types of masks under investigation have significant differences in terms of particle capture efficiency and bacterial filtration performance. In addition, there is a significant correlation between bacterial and particle filtration efficiency.
 

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Introduction: Improving health and the environment is one of the components of development, social welfare, and economic growth. Another influential factor in increasing health costs and reducing social welfare is work-related accidents and diseases, which impose high costs on individuals, industries, and the national economies of countries. Therefore, using multi-criteria decision-making methods, the present study provided a conceptual model to identify and rank work-related diseases’ environmental and health costs.
Material and Methods: The present study was conducted in 2023. A classification model for the economic evaluation of environmental and health costs of occupational diseases was developed to achieve the study’s aim. In the current research, the Delphi method was used to identify health and environmental criteria, and the Analytic Network Process (ANP) was used to weight the sub-criteria. Finally, the cost of health and the environment was estimated based on the available information. Naft Tehran Hospital (NSHT) was also selected as a case study site.
Results: The results showed that the drug and medical equipment cost factor, with a weight of 0.312 in the treatment sector, and the particular and infectious waste cost factor, with a weight of 0.085, were the most critical factors in the economic evaluation. Also, the parametric model results showed that 99.84% of the total costs are related to health costs, and 0.16% are related to environmental costs. In general, the results of this research showed that 61.3% of the costs of the health sector are related to the two sectors of medicine and medical equipment and the cost of service personnel, and 91.7% of the costs of the environmental sector are related to wastewater treatment and the cost of electricity consumption.
Conclusion: This study presented a semi-quantitative model to estimate health and environmental costs caused by occupational diseases. The results can create a novel scientific insight into implementing control measures using the optimal point of cost-benefit parameters. Implementing this integrated model can be a practical and effective step in allocating resources and prioritizing interventions.
 

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Introduction: Shift work combined with the nature of duty in occupations such as nursing can lead to the spread of psychological consequences and disorders in nurses. The aim of this study was investigating the cognitive and psycho-social consequences associated with shift work in nurses.
Material and Methods: This study was performed in 7 hospitals in 2023. The study population was 636 nurses. Data collection tool in this study was part of a comprehensive questionnaire that translated and modified by Choobineh et al. The data were analyzed using IBM SPSS software v. 22.0, and significance level in this study was considered 0.05.
Results: Out of 636 studied nurses, 474 were shift workers and 162 were day workers. The means of age and work experience of the study population were 37.26±5.25 years and 11.60±4.78 years, respectively. The results showed that the prevalence of psychological consequences in the shift workers group was significantly more than day work nurses (p<0.05). The highest prevalence of cognitive and psycho-social consequences in shift work nurses were related to fatigue (39.66%), insomnia (36.08) and decreased sleep quality (35.44%), respectively.
Conclusion: The findings of this study indicated that the parameters of the shift work system, working hours per week, education and hospital ward are the most important factors affecting the prevalence of cognitive and psycho-social consequences and sleep disorders in the nurses. Therefore, it is suggested that a separate program should be designed and implemented for each hospital ward to control and manage the psychological consequences associated with shift work in nurses.

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Introduction: Sugarcane is an important and strategic product in many countries, including Iran. While the introduction of mechanization, e.g., sugarcane harvesting machines, has significantly enhanced the production process, operators of these machines still face many ergonomic and safety challenges. 
Material and Methods: The present study investigated the ergonomic status of sugarcane harvester operators by examining some of their physiological and physical evaluations. Physiological evaluations included heart rate, oral temperature, and energy consumption of the operators, perceptual strain index, and physiological strain index. Physical evaluation included estimating the amount of pain and discomfort in body segments. The correlation between pain and discomfort of body parts with some demographic and physiological indices of users was investigated using IBM SPSS 24 software.
Results: Sugarcane harvester operators’ heart rate, energy consumption, and physiological strain index were 79.05 beats/min, 18.81 kJ/min, and 0.83, respectively. The average of three indices of thermal sensation, perceived exertion of activity, and perceptual strain index were estimated as 4.40, 9.21, and 8.86, respectively.
Conclusion: Pain and discomfort in the neck and back segments, like many agricultural activities, had the highest rate among the body parts. Also, shorter and thinner operators reported higher pain and discomfort in some segments of the body. 
 

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Introduction: Despite advancements in road safety and vehicle design, road accidents remain prevalent, a quarter of which are caused by driver distraction. This issue is particularly critical in the public transport sector, especially among urban bus drivers, as distraction can lead to serious injuries and fatalities. Accordingly, this study explored the factors influencing distraction among urban bus drivers through a qualitative approach and a macroergonomics perspective.
Material and Methods: In this study conducted in 2024 in Tehran, 18 urban bus drivers were selected through cluster sampling. The participants included 10 drivers from bus rapid transit (BRT) system and 8 drivers from non-BRT services. Data were collected through semi-structured interviews with the drivers as well as on-site observations. Subsequently, a directed qualitative content analysis approach, based on the balance theory model, was used to analyze the collected data.
Results: The findings revealed that the primary sources of distraction belonged to six levels of the work system, the most cited of which were environment, tasks, and organization. Specifically, inappropriate behavior of other street users as an environmental factor and the driver’s interactions with passengers as task-related factors were identified as key sources. Additionally, organizational factors such as interactions with supervisors and colleagues, as well as salary issues, were significantly important. The participants very limitedly expressed using mobile phone while driving as a main distractor to their driving.
Conclusion: The current study identified various influential factors, spanning different levels of the work system, affecting bus drivers’ distraction, including generic factors that impact all urban drivers and specific factors that uniquely affect bus drivers. Addressing these factors through providing appropriate education for both passengers and street users along with implementing management strategies in the organization to enhance intra-organizational relationships and organizational support can lead to the safety of the bus drivers.
 

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Introduction: This study aimed to analyze the effects of endurance training (Aerobic) on the levels of inflammatory markers (IL-6/TNF-α) and some metabolic parameters in male rats with non-alcoholic fatty liver disease to investigate the feasibility of using exercise training to reduce inflammation.
Material and Methods: A total of 44 Wistar rats were randomly assigned into two groups: (I) standard diet group of 22 rats and (II) high-fat diet group with 22 rats supplemented with free access to fructose water. After 17 weeks, two rats from each group were sacrificed, and liver tissue was collected for hematoxylin-eosin staining. Subsequently, the remaining 20 rats in the (I) group were divided into a training group (T) and a control group (C). The 20 rats in the (II) group supplemented with fructose water were divided into a fatty liver group (FL) and a fatty liver + training group (FL+T), each comprising ten rats. In the next phase, the T-groups underwent an eight-week endurance training intervention. Then, IL-6, TNF-α, glucose, insulin, insulin resistance and sensitivity levels were measured.
Results: The results of the present study showed that as a result of a high-fat diet with liquid fructose in HFD+HF group rats, non-alcoholic fatty liver disease (NAFLD) with complications such as a significant increase in the levels of IL-6 and TNF-α, Hepatic dysfunction, and metabolic parameters were disturbed (p<0.001). However, endurance training improved most of these complications by reversing the disease process (p<0.001).
Conclusion: According to the results of the present study, it can be concluded that the improvement of inflammatory markers, liver dysfunction, and metabolic parameters through endurance training is one of the key mechanisms of exercise in the treatment of NAFLD, the consequences of which may show the importance of endurance training in treatment of NAFLD highlights.

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Introduction: Operating room personnel are involved with occupational physical activities such as repetitive bending, holding surgical tools and standing for long hours that can lead to musculoskeletal disorders (MSDs). Low back pain (LBP) is the most prevalent and costly problem among these disorders. The aim of this study was to determine the relationship between occupational physical activity, LBP and disability among operating room personnel.
Material and Methods: A total of 60 operating room personnel voluntarily participated in the study, all of which had at least two years of working experience. At the end of a working week, the degree of disability and pain were assessed by Graded Chronic Pain (GCP) questionnaire. The International Physical Activity Questionnaire (IPAQ) was used to evaluate the level of physical activity. Simple linear regression was conducted to investigate the relationship between physical activity, LBP and disability. 
Results: The survey using the GCP questionnaire revealed that 58.3% of participants reported experiencing occupational back pain, while 41.7% reported no back pain.  Among those with back pain, the average pain intensity was rated 43.11 (18.22) on the scale.  Pain remained stable for an average of 2.3 days (standard deviation = 0.95).  The average level of disability associated with back pain was 32.09 (27.44). Statistical analysis using simple linear regression showed a significant relationship between back pain and several factors: vigorous physical activity (p-value = 0.02), prolonged sitting time (p-value = 0.01), and chronic pain (p-value < 0.001).
Conclusion: Occupational physical activity characterized by low intensity, but high repetition and standing for a long time in fixed postures were the most significant contributors to lumbar back pain among operating room personnel. Chronic pain in this population was reported as grade 2, indicating severe pain with minimal disability; if left unaddressed, this could lead to movement restrictions.

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Introduction: Workplaces often contain potential risks, such as exposure to toxic chemicals. Conducting a thorough health risk assessment helps employers recognize these dangers and implement necessary controls. In the 20th century, modern risk assessment frameworks began to be established with the rise of public health agencies.
Material and Methods: The present study is a narrative review. In order to obtain necessary information, Persian and English texts were searched in Web of Science, PubMed, Scopus, SID and Magiran databases. Keywords such as “health risk assessment”, “chemicals” and “nanomaterials” were used in this study.
Results: Both quantitative and qualitative health risk assessments play critical roles in occupational health, with each method providing different levels of depth and accuracy depending on the situation. EPA Model, Monte-Carlo Simulation, Physiologically Based Pharmacokinetic (PBPK) Modeling, Quantitative Structure-Activity Relationship (QSAR) Models, Probabilistic Risk Assessment (PRA), Life Cycle Impact Assessment (LCIA), and Biologically Based Dose-Response (BBDR) Models, are among the most important quantitative methods for assessing the health risk of chemicals. COSHH Model, ICCT Model, ICMM Model, Australian Model, and Romanian Model, are the most important qualitative methods for health risk assessment of chemicals. In addition to the quantitative and qualitative methods, semi-quantitative methods like Singapore Model, LEC Method, and SEP Model, have also been proposed for assessing the health risk of chemicals. The preference for qualitative over quantitative methods in the risk assessment of activities involving nanomaterials stems from substantial uncertainties, limited data availability, and the unique and complex behaviors of nanomaterials in the workplaces.
Conclusion: Overall, the evolution of health risk assessment methods reflects a continuous drive towards greater accuracy, reliability, and relevance. As we continue to innovate and expand our knowledge, the field is well-positioned to address the complex and evolving landscape of chemical and material risks, ensuring the protection of human health and the environment.