Journal of Health and Safety at Work

---

Introduction: Traffic noise has been thought as a major environmental stress in modern societies, and the cause of physiological and psychological disorders according to the World Health Organization. Moreover, traffic noise can interfere with mental performance. However, there is little coherent evidence showing the effect of traffic noise on individuals’ performance. Hence, this paper aimed to address the role of traffic noise in participants’ mental performance considering the complexity of the activity.
 

Material and methods: Thirty-five master students studying in Tehran University of Medical Science were recruited for this study. Traffic noise was recorded by tape recorder and the traffic noise level was simultaneously measured by sound meter. Then, participants had been separately sitting in silent compared to traffic noise environment before they performed the tests including “S₃”-type Choice Reaction Time (CRT) test as a simple activity and “S1”-type Determine Test (DT) as a complex activity taken from “Vienna Test System” software package.
 

Results: The comparison between scores resulted from DT and CRT tests ,before and after exposure to traffic noise under simple activity conditions, showed that there was little increase in mean score of reaction time (P-value=0.47) and motor time (P-value=0.49), showing no statistically significant changes in these variables. On the contrary, following exposure to traffic noise, the DT test under complex activity condition revealed that there is a clear decreasing trend in median reaction time(P=0.001), number of stimuli (P=0.014) and number of reactions (p=0.009) in participants, and also, no significant differences were found in correct responses (P=0.091) and incorrect responses (P=0.073).
 

Conclusion: One of the most significant findings emerged from this study is that traffic noise seems to have no effect on the mentioned variables under simple activity condition. However, traffic noise has devastating effects on median reaction time, number of appeared stimuli and reactions under complex activity condition.

---

Introduction: Unit risk management is a critical component of gas refining management, as risks that are not well-managed may lead to trip production failures. The present study aimed to provide a structural model for investigating the role and effect of different variables on stopping the gas production process in the gas refinery.
Material and Methods: This study was a retrospective cross-sectional and systematic analysis, which was carried out on key risks in the trip gas sweetening unit in a gas refinery industry located in Asaluyeh, Iran. The systems analysis was applied by using Fishbone Diagram, and then data modeling was prepared by Structural Equation Modeling (SEM) for an incident that occurred during gas sweetening production. Tools for the data analysis included the SPSS 24 and Smart PLS 2 software.
Results: Results of this research indicate that “Environment Risk” with a path coefficient of 0.943 and T- Value of 103.791; “Cost Risk” with a path coefficient of 0.937 and T- Value of 95.168; “Implementation of management system Risk” with a path coefficient of 0.847 and T- Value of 35.23; “Accident Risk” with path coefficient of 0.577 and T- Value of 25.410; “Time Risk” with path coefficient of 0.758 and T- Value of 15.121; “Human Error Risk” with path coefficient of 0.712 and T- Value of 11.215 had the most important coefficients of the paths respectively, that are effective in stopping production concerning other risks. Also, by comparing the path coefficients of the risks we can see that the impact of each of the risks on stopping production is different.
Conclusion: The findings of the present study revealed that a combination of variables can affect stopping production in the gas industry. Therefore, the role of these risks in losses in the refinery system should be investigated.

---

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. 

---

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.