Journal of Health and Safety at Work

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Introduction: In all societies, tools and equipment are generally designed for right-handed people, who make up approximately 90% of the population, but left-handed and ambidextrous people (those who use both hands in manual activities) also live among us. Even in delicate and sensitive jobs. This research investigated the relationship between the spectral effect of the dominant hand and grip strength and hand dexterity.
Material and Methods: A cross-sectional study was designed to measure the power and precision grip of 182 adult participants (56% female and 44% male). The dominant hand of the participants was determined using the Edinburgh Dominant Hand Questionnaire. Power grip strength was measured using the Constant 14192-709E. Pinch grip test was performed using Saehan Hydraulic Pinch Gauge SH5005 for both hands separately. Dexterity of both hands was also measured using the Pegboard 32020A tool.
Results: Power and precision grips were more common in men than in women (P<0.001). Power grip differed between right- and left-handed women (P=0.019), with right-handed women having greater grip strength. The Precision grip of left-handed men was significantly (P<0.001) greater than that of right-handed men. Hand dexterity of left-handed men was significantly (P<0.001) higher than that of right-handed men. Two-handed agility (P<0.001) and assembly dexterity (P<0.001) are significantly higher in ambidextrous people than in right- and left-handed people.
Conclusion: The power, precision grip and dexterity are different between women and men. The grip strength of men is stronger than that of women. Ambidextrous people have more dexterity and assembly agility, so in jobs that require the use of two hands, they perform better and will be recommended for employment in this category of jobs. 

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Introduction: Fire safety in healthcare centers is crucial due to the limited evacuation capacity of the occupants and the necessity of not disrupting the operation in these centers. In this study, the fire risk of a public hospital was evaluated using the Fire Risk Assessment Method for Engineering (FRAME). Additionally, the factors affecting fire safety in the hospital were analyzed quantitavely, and fire control strategies were presented. 
Material and Methods: First, the fire risk assessment checklist was filled in all the hospital departments. Then, the values of the factors affecting fire safety were obtained. In the next step, the fire risk for the building, occupants and activities were estimated using Excel software-FRAME. Finally, control strategies and intervention measures were presented based on the value of these factors. 
Results: In the hospital under study, 22% of the departments posed an undesirable fire risk to the building and its property. On the other hand, 90% of the departments had risk levels that were undesirable for the occupants. The results of the initial risk (R0) showed that a balance between potential fire risk and risk acceptance can be established by implementing manual fire extinguishing systems and automatic detectors in all departments. 
Conclusion: ased on the condition of the hospital studied, a balance between potential fire risk level and risk acceptance level was not established. Therefore, there is a need for fire control measures, especially fire safety measures for the occupants. The results of this study can be useful for readers and experts in interpreting fire risk assessments and presenting detailed control measures based on the risk assessment and the value of the parameters.

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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: Safety in process industries is of paramount importance, as these industries typically deal with hazardous chemicals and complex processes that can lead to irreparable consequences in the event of accidents. The present study aims to evaluate domino effects and analyze the vulnerability of storage tanks using graph theory and Bayesian networks in a process industry. This approach can help identify system vulnerabilities and facilitate the prediction of potential accidents, ultimately leading to improved safety measures.
Material and Methods: In this study, after collecting initial information related to the location of storage tanks and determining accident scenarios, the tanks under investigation were selected based on the type of stored materials and their layout, with input from experts. These tanks were modeled as nodes in a graph, and the probability of accident spreading among them was represented as edges in the graph based on the amount of heat radiation. Additionally, for modeling domino effects and analyzing vulnerability, graph theory and Bayesian networks were employed.
Results: Based on the target tanks related to the pool fire scenario, domino effects in the tanks were identified and modeled as a theory graph. Tank number 4 was determined to be the most influential and susceptible tank in the spread and initiation of domino effects, with the highest betweenness index (0.2381), outcloseness index (0.35211), and incloseness index (0.3663). Additionally, based on the allcloseness index, the most likely sequence of the tank involvement in fires caused by domino effects was identified.
Conclusion: In order to reduce the likelihood of exacerbating domino effects, modeling the effects using Bayesian networks and graph theory is proposed; the results can also be applied to optimize fire suppression strategies. Additionally, vulnerability analysis through graph theory and the assessment of tanks regarding their potential for fire initiation and spread can be beneficial in managing the risks associated with domino effects.

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Introduction: Biomechanical risk factors, including wrist and elbow angle and standing and sitting position, are the primary factors affecting hand grip strength and perceived exertion. The interaction of these factors can include different effects on grip strength and perceived exertion. Therefore, the present study examines the interaction of varying wrist and elbow angles in sitting and standing postures on the variability of grip strength and perceived exertion.
Material and Methods: In the present study, 30 students (15 females, 15 males) aged 19-30 participated. The average grip strength was measured by a dynamometer for 12 different positions based on the angle of the wrist and elbow in both standing and sitting postures. Perceived exertion was also assessed using the Borg CR-10 scale for each setting. Data analysis was performed using SPSS 23. The Wilcoxon test was applied to compare perceived exertion between standing and sitting postures. Furthermore, a three-way ANOVA was performed to examine interactions between posture (standing/sitting), elbow, and wrist angles. Mauchly’s Sphericity Test was applied to confirm the ANOVA assumptions, and effect sizes for multivariate analysis were calculated (partial η2).
Results: In both sitting and standing postures, the highest average grip strength was observed at a 0-degree wrist angle with a 90-degree elbow angle (standing: 28.6 ± 10.8, sitting 25.8 ± 9.8), while the lowest average grip strength was recorded at full wrist extension with a 0-degree elbow angle (standing: 19.3 ± 6.5, sitting 17.9 ± 6.9). In all three elbow angles examined (0°, 60°, and 90°), the highest value of perceived exertion was recorded in the full extension of the wrist. The changes in the grip strength at different angles were the same for sitting and standing postures, yet the hand grip strength was higher in the standing than the sitting posture (P-value<0.001). The effect of each of the studied factors (sitting and standing postures, wrist angle, and elbow angle) alone on hand grip strength and perceived exertion was deemed to be significant (P-value<0.001). Regarding the two-way interactions of the research variables, the interaction effect of elbow and wrist angles on grip strength (partial η2=0.09, P-value=0.015) and perceived exertion was significant (partial η2=0.08, P-value=0.06). Furthermore, findings indicated that the wrist angle had a more pronounced effect on the value of the perceived exertion (partial η2=0.31, P-value<0.001).

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Introduction: Micro-perforated panel (MPP) absorbers are emerging as next-generation absorbers due to their considerable advantages. However, their main drawback compared to other absorbers is their limited bandwidth. This study aims to investigate methods for enhancing the bandwidth of an MPP in the frequency range of 1 to 1500 Hz through simulation using the Finite Element Analysis (FEA) in COMSOL software.
Material and Methods: The modeling was conducted using FEA in COMSOL version 5.3a. To increase the bandwidth, techniques such as series-parallel configurations, symmetrical and asymmetrical air gap depths, and the incorporation of two porous absorbing materials in symmetric and asymmetric air gap layers were employed. In the initial phase, the best configuration was selected and retained for the subsequent stages.
Results: The optimal arrangement involved two upper MPPs having larger holes and a lower perforation percentage compared to the two lower MPPs. It was also found that increasing the depth difference between the air layers of the upper and lower MPPs led to a greater increase in bandwidth than when they were closer together. Furthermore, the use of fibrous porous materials in one of the layers resulted in a reduction of resonance peak while enhancing the bandwidth.
Conclusion: MPP absorbers exhibit diverse behaviors due to their Helmholtz structure and parametric design. If their constituent parameters are tailored to match the acoustic characteristics of the target sound, they achieve optimal efficiency. Additionally, employing numerical methods such as FEA serves as a suitable alternative to more costly laboratory methods.

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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: Volatile organic compounds (VOCs) are hazardous toxic pollutants in the air, which are released from various industrial sources. Due to the adverse effects of xylene on health, the effective removal of VOCs from the air by nano sorbents is crucial. In this study, nanographene (NG) and nanographene oxide (NGO) were used as adsorbents to investigate the efficiency of xylene removal.
Material and Methods: In this study, in order to investigate the absorption efficiency of nanographene and nanographene oxide after the synthesis of nano absorbents in a dynamic system, xylene vapor was produced in a chamber in pure air and stored in a Tedlar sampling bag and then transferred to the adsorbent. Subsequently, the effect of various parameters such as xylene concentration, inlet air flow rate, and absorbent mass values at 32% humidity and 25°C temperature on the absorption rate and performance of the desired absorbents was investigated. Finally, the gas chromatographic flame ion detector (GC-FID) determined the concentration of xylene in air after the adsorption-desorption process.
Results: The average adsorption efficiencies for NG and NGO were found to be 96.8% and 17.5%, respectively. The characteristics of the NG and NGO adsorbents indicated that the particle size range was less than 100 nanometers.
Conclusion: The results demonstrated that the adsorption efficiency of NG for the removal of xylene from the air is higher than that of NGO. The GC-MS method validated the proposed approach in real air samples.

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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: The increasing advancement of technology in the field of digital technology and automation has led to a change in the line of work and job content, and it seems that organizations are pushing their employees towards harder and longer work, which affects the health of employees. This study investigated the impact of job demands and resources on overtime and work-related health through the mediation of workaholism and work engagement.
Material and Methods: The work is a descriptive survey in terms of purpose and nature. The study’s statistical population consisted of employees of Isfahan Metro Company (320 people), of which (175 people) were studied by Simple Random Sampling. To collect the required information, Spence and Robbin’s (1992) Addiction Questionnaire, Lodahl and Kejner’s (1965), Langseth-Eide’s (2019) Perceived Health-Related Questionnaire, and Bryson Bangers’ Caricature Content (1998) were distributed and supplemented based on a Likert scale. A Structural equation model (SEM) was used to test the hypotheses.
Results: The results showed that job demands on workaholism (β=0.394, T=5.969, P <0.05) and job resources had a positive and significant relationship with work engagement (β =0.502, T =7.832, p <0.05), and workaholism and work engagement on the relationship between job demands and resources over time and health. Mediating work-related perceptions (Z= 4.383, Z= 2.189, Z= 3.797). In addition, job resources did not moderate the relationship between job demands and workaholism (β= -0.049, T =1.333, p> 0.05). 
Conclusion: The results of this study showed that there is a distinction between workaholism and work engagement as two different types of hard work (i.e., negative and positive) in the health process in the JD-R model. 

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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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Material and method:  In this study, industrial accidents during gas pipeline excavation and piping operation were analyzed using Bowtie method. The Fuzzy DEMATEL method was used to determine relationships between accident root causes, and the Fuzzy AHP method was used to compare pairs of causes and determine their weight. Finally, Bowtie and DEMATEL outputs were mapped in Bayesian networks and important risk factors of accident were determined.
Introduction: Identifying and modeling the root causes of accidents can play an important role in preventing them. The purpose of this study is to identify and model the causes of gas pipeline excavation and piping operation accidents using Bayesian network (BN) and fuzzy DEMATEL.
Results: The most important risk factors for trench collapse accident were risk management (16% impact weight), competency assessment (14.2% impact weight), supervision (13.8% impact weight), work permit system (13.7% impact weight), compliance with requirements and guidelines (13.4% impact weight), training (11.4% impact weight), HSE system (9.5% impact weight) and contractor management (8%impact weight).
Conclusion: From the results obtained in this study, it can be said that the risk management and competency assessment with a higher weight percentage play a more important role in the occurrence of trench collapse accident. The results of this study can be used to prioritize corrective actions to prevent trench collapse accidents in gas pipeline excavation and piping operations.
 

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Introduction: Heat stress is a common environmental risk factor for many occupations, which can lead to increased fatigue during cognitive tasks. Fatigue is a multifactorial phenomenon that is affected by various environmental, physiological, and psychological factors, and can affect biomechanical, physiological, and psychological components. This study focuses on the impact of environmental, individual, and physiological factors, and burnout on general fatigue.
Material and Methods: This descriptive-analytical study was conducted among 189 employees of the Iran Oil Company at both indoor and outdoor workstations. Heat stress was measured using the (WBGT) index, and thermal strain risk was evaluated. Variables such as skin temperature, ear temperature, blood pressure, and heart rate were also monitored. To assess general fatigue and occupational burnout, (MFI) and the Maslach Burnout Inventory were completed by the employees.
Results: The results revealed that 79.9% of the employees were exposed to heat stress, with repair workers experiencing the highest levels of emotional exhaustion (23/38), depersonalization (15/34), general fatigue (10/00), and physical fatigue (9/05).  Statistically significant relationships were found between heat stress and fatigue and decreased motivation, between all components of burnout and general fatigue, and between core temperature, blood pressure, and general fatigue (p<0.05). Notably, demographic factors such as marital status, smoking status, and education level did not significantly influence fatigue scores.
Conclusion: Fatigue is strongly associated with heat stress, physiological variables such as body temperature and blood pressure, burnout, personal habits such as sleep duration and exercise, and the type of job. These findings suggest that in hot work environments, monitoring physiological variables and environmental factors can help identify and address fatigue issues.

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Introduction: The Total Quality Safety Management (TQSM) model is a tool used to assess the performance of occupational health and safety (OHS) management. This study evaluated the OHS management performance in two edible oil production factories using the TQSM model.
Material and Methods: A total of 78 OHS-related evaluation criteria across four main areas of the TQSM model were assessed at the Saboos Mazand (Factory 1) and Mino Caspian (Factory 2) factories, located in Mazandaran Province, Iran. The four areas included Total Quality Management (TQM), the ISO 9001 Quality Management System guidelines, the Voluntary Protection Program (VPP), and Process Safety Management (PSM). The study population consisted of 20 individuals from each factory, including managers, supervisors, and members of the OHS Committee, all with at least one year of experience in their respective roles. Participants were selected using a convenience sampling method.
Both factories had established active management systems for quality management (ISO 9001), customer satisfaction management (ISO 10002), and Hazard Analysis and Critical Control Points (HACCP) at the time of the study, reflecting the nature of the industry.
Results: The total scores achieved by Factory 1 and Factory 2 across the four main areas were as follows: 52.11 and 51.8 in the TQM area, 43.94 and 45.5 in the QMS-ISO 9001 area, 45.23 and 46.45 in the VPP area, and 30.22 and 30.06 in the PSM area. The overall scores obtained in the TQSM model were 171.51 for Factory 1 and 173.81 for Factory 2, corresponding to 54.97% and 55.7% of the maximum achievable score, respectively. No significant difference was observed between the mean scores across the four areas of the TQSM model for the two factories (p > 0.05).
Conclusion: Both factories exhibited an overall average performance level in OHS management. The evaluation criteria across the four areas of the TQSM model indicated weak to moderate conditions in the assessed subareas. Effectively using this model highlighted the organizational and operational areas requiring increased effort and focus to enhance OHS management performance in both factories.