Journal of Health and Safety at Work

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Introduction: Microperforated panels (MPPs), often considered as potential replacements for fiber absorbers, have a significant limitation in their absorption bandwidth, particularly around the natural frequency. This study aims to address this challenge by focusing on the optimization and modeling of sound absorption in a manufactured MPP.
Material and Methods: The study employed Response Surface Methodology (RSM) with a Central Composite Design (CCD) approach using Design Expert software to determine the average normal absorption coefficient within the frequency range of 125 to 2500 Hz. Numerical simulations using the Finite Element Method (FEM) were conducted to validate the RSM findings. An MPP absorber was then designed, manufactured, and evaluated for its normal absorption coefficient using an impedance tube. Additionally, a theoretical Equivalent Circuit Model (ECM) was utilized to predict the normal absorption coefficient for the manufactured MPP.
Results: The optimization process revealed that setting the hole diameter to 0.3 mm, the percentage of perforation to 2.5%, and the air cavity depth behind the panel to 25 mm resulted in maximum absorption within the specified frequency range. Under these optimized conditions, the average absorption coefficient closely aligned with the predictions generated by RSM across numerical, theoretical, and laboratory assessments, demonstrating a 13.8% improvement compared to non-optimized MPPs.
Conclusion: This study demonstrates the effectiveness of using RSM to optimize the parameters affecting MPP performance. The substantial correlation between the FEM numerical model, ECM theory model, and impedance tube results positions these models as both cost-effective and reliable alternatives to conventional laboratory methods. The consistency of these models with the experimental outcomes validates their potential for practical applications.

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Introduction: The safety harness is a critical device for preventing falls from height, particularly in the construction industry. This study aimed to identify the factors contributing to the non-use of safety harnesses during work at height and to evaluate the comfort, satisfaction, and usability of these harnesses among construction workers in Tehran using a custom-designed tool.
Material and Methods: A semi-structured interview was conducted with construction workers to identify the factors influencing the non-use of safety harnesses. The collected data were analyzed using MAXQDA 10 software. Based on the results, which revealed dissatisfaction with the current safety harnesses, the levels of comfort, satisfaction, and usability were assessed using the Safety Harness Usability and Comfort Assessment Tool (SHUCAT) questionnaire.
Results: The reasons for not using safety harnesses were categorized into four main groups: management factors, worker attitudes, comfort, and harness design. These were further subdivided into 27 subgroups. The average satisfaction and comfort scores for safety harnesses were 26.8 ± 6.25, indicating that workers generally felt uncomfortable and dissatisfied with their harnesses. The average usability score was 38.70 ± 5.60, reflecting poor usability of the harnesses.
Conclusion: Improving the safety harness design could enhance workers’ comfort and satisfaction, increasing their willingness to use the equipment. Incorporating feedback from users and experts into the design process can help address the identified shortcomings and result in better product development.

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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 the Bayesian network (BN) and fuzzy DEMATEL.
Material and Methods: In this study, industrial accidents during gas pipeline excavation and piping operations were analyzed using the Bowtie method. The fuzzy DEMATEL method was employed 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 to determine the important risk factors for accidents.
Results: The most important risk factors for trench collapse accidents were as follows: 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: Based on the results, it was demonstrated that risk management and competency assessment, having the highest weight percentages, play the most significant roles in the occurrence of trench collapse accidents. The findings of this study can inform the prioritization of corrective measures to prevent trench collapse accidents in gas pipeline excavation and piping operations.

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Introduction: Barriers play a critical role in mitigating risks and preventing catastrophic incidents in process industries. Human and Organizational Factors (HOFs) significantly influence the performance of safety barriers. This systematic review investigates existing frameworks and methods for assessing the impact of HOFs on safety barrier performance.
Material and Methods: A systematic search was conducted across the Scopus and Web of Science databases, following the PRISMA guidelines. The search aimed to identify studies presenting methodologies for evaluating the influence of HOFs on safety barrier performance in process industries. Data were subsequently extracted from the 16 included studies.
Results: The 16 studies included in this research presented various methods and frameworks examining the impact of HOFs on different types of safety barriers, including technical, operational, and human barriers, across industries such as oil and gas, chemical, and steel. Barrier and Operational Risk Analysis (BORA) emerged as the predominant framework among the studies. Research on operational and human barriers, which depend on human actions and procedures, frequently identified factors such as competence, training, communication, and supervision as key influencers of performance. In contrast, studies on technical barriers highlighted the importance of assessing factors such as maintenance management and procedural compliance.
Conclusion: This research highlights the critical role of HOFs in safety barrier performance within process industries. By systematically reviewing existing methodologies, the study identified their strengths and weaknesses. Findings underscore the need to account for uncertainties in expert judgments and the interplay between HOFs in evaluation models. The integration of fuzzy logic and Bayesian networks is proposed to enhance evaluation processes. Future research should prioritize the development of unified frameworks that address the limitations of current approaches while expanding their applicability across diverse industries. 
 

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Introduction: Measuring and monitoring the process safety management system is essential to reduce the risk of accidents in process industries. For this purpose, lagging and leading process safety performance indicators are utilized. The aim of the present study is to select, validate and prioritize the leading indicators of process safety performance.
Material and Methods: First, the leading indicators associated with risk factors affecting hydrocarbon liquid tanks were identified and selected based on the guidelines provided by the CCPS, HSE UK, OGP, and relevant scholarly articles. After choosing the appropriate indicators, the content validity of the indicators was studied. In the next step, indicators with acceptable content validity were studied by experts in terms of applicability and importance using fuzzy weighting.   
Results: Out of 18 performance indicators related to risk factors influencing the performance of operating personnel, 3 indicators were eliminated due to content validity ratio (CVR) and content validity index (CVI) scores below acceptable levels. The remaining 15 indicators advanced to the next stage of the study. All 4 indicators related to the performance of maintenance personnel achieved acceptable CVR and CVI scores and were also included in the next stage. Of the 13 indicators defined for equipment performance, 3 were excluded due to low CVR or CVI scores, and 10 progressed to the subsequent phase. For firefighters, 9 indicators were identified, of which 2 were eliminated due to low CVR or CVI, and 7 advanced to the next stage. In this stage, all 36 indicators achieved acceptable applicability scores and were subsequently weighted.
Conclusion: The 36 final indicators presented in this study can be used to measure process safety performance in the oil industry. Although the present study was a case study on liquid hydrocarbon tanks, most of the indicators presented can be applied to other sectors of the oil industry. In addition, the weights specified for each of these indicators can be used to prioritize the indicators. 

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Introduction: Occupational diseases and workplace accidents have significant financial impacts on industries, communities, and nations each year. Risk assessment is considered an effective tool for managing these issues; however, many organizations fail to implement it successfully. This study explores this challenge from the perspective of Health, Safety, and Environment (HSE) officers.
Material and Methods: In this study, 30 Semi-structured individual interviews were conducted with HSE officers. Inductive content analysis was used for analyzing interviews. After analyzing the interviews, the codes in the interviews were categorized. To ensure credibility and transferability, participant checking and consultations with experts in the field of risk assessment were conducted.
Results: After analyzing the interviews, seven main categories were identified, each comprising several sub-categories. The main categories included: Resources, Technical Knowledge, Legal and Regulatory Barriers, Cultural Issues, Absence of Risk-Based Thinking in the Organization, Individual Issues, and Lack of Interaction and Communication.
Conclusion: This study revealed that seven major barriers hinder the implementation of risk management systems and the execution of risk assessments in the industries of East Azerbaijan Province. These obstacles can directly affect the identification, analysis, and control of risks, ultimately reducing the effectiveness of occupational health and safety processes. Therefore, to conduct effective risk assessments and enhance safety levels in industrial environments, it is essential for policymakers, industry managers, and regulatory bodies to accurately identify and analyze these barriers and develop appropriate solutions to address them. Moreover, designing and implementing educational programs, restructuring management systems, and strengthening interactions between regulatory organizations and industries can contribute to improving risk assessment processes and safety management in this sector.

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Introduction: Surgical technologists encounter a challenging work environment, and therefore, they require well-organized workplaces and appropriate health-related training. This study aimed to determine the effect of a participatory ergonomics program on musculoskeletal disorders (MSDs) and general health among surgical technologists
Material and Methods: This single-blind randomized controlled trial was conducted in 2023-2024 in operating rooms of teaching hospitals in Isfahan, Iran. The study population comprised 88 surgical technologists meeting the inclusion criteria. One hospital was randomly selected as the intervention site, while the remaining hospitals served as the control group. Data were collected using a demographic questionnaire, the Cornell Musculoskeletal Discomfort Questionnaire (CMDQ), and the 28-item General Health Questionnaire (GHQ-28). Initially, all participants in both groups completed baseline assessments. The intervention group received a participatory ergonomics program. Follow-up assessments were conducted at 3 and 6 months post-intervention in both groups. Data were analyzed using SPSS version 24 employing both descriptive and inferential statistical methods, with a significance level set at 0.05.
Results: Before the intervention, no significant differences were observed between the intervention and control groups in terms of mean scores for general health and MSDs (p=0.55). Three months post-intervention, a significant difference was found in the mean score of lower extremity MSDs between the groups (p=0.033). Six months post-intervention, a significant difference was observed in the mean score of Trunk region MSDs between the groups (p=0.038). Significant differences in mean general health scores were observed between the groups at 3 months (p=0.001) and 6 months (p=0.001) post-intervention, with the intervention group reporting better general health compared to the control group.
Conclusion: The implementation of a participatory ergonomics program can improve general health and reduce MSDs among surgical technologists.

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Introduction: Exposure to noise is one of the most common harmful factors in the dental profession that can have significant consequences. Unfavorable acoustic conditions of the environment can also worsen the conditions and lead to reduced speech clarity, auditory fatigue, and reduced quality of communication between the doctor and the patient. In this regard, designing effective acoustic interventions can play an important role in improving sound.
Material and Methods: This study was conducted in an academic dental clinic. After measuring the sound pressure level, reverberation time, and speech transmission index, the amount of rock wool absorber required was determined using the Sabin formula. The panels were structurally installed on the clinic walls, and after 24 hours, the sound pressure level, RT60, and STI were measured again, and appropriate statistical tests were used to determine the effect of the intervention.
Results: The results showed that the sound pressure level before and after the panel installation was significantly different and decreased after the intervention (p-value <0.05). The reverberation time at the dominant frequency of 2000 was 0.992 seconds before the intervention and reached 0.599 seconds after the intervention (p=0.027, z= 2.207). The speech transmission index in the center of the room improved from 0.64 and the “average” level to 0.85 and the “excellent” level, indicating an increase in speech clarity.
Conclusion: The acoustic intervention was able to bring the clinic’s acoustic indices closer to the recommended ranges. The significant reduction in reverberation time and sound pressure level along with the increase in the speech clarity index indicates the high efficiency of this intervention. Utilizing sound absorbers can be a low-cost and feasible solution to improve acoustic conditions and improve speech communication in dental treatment and educational environments.