Occupational Medicine

Examining the role of the hole and the orientation of the baffle on the loss of sound transmission in reactive mufflers using COMSOL software simulation

Alimohammadi I — 2025-04-12

Introduction: Nowadays, noise pollution in the environment has become as a worldwide health concern. A large share of this noise comes from vehicles, where mufflers in their exhaust systems are essential for lowering engine noise levels. Proper muffler design and modifications to its geometric parameters, including adding holes in the baffle and changing their orientation, can significantly influence the acoustic performance of mufflers and contribute effective in enhanced noise reduction.

Materials and Methods: The finite element numerical method was utilized to examine the acoustic effectiveness of the analyzed mufflers. At first, the mufflers were designed and modeled using COMSOL software. Subsequently, by modifying the desired geometric parameters, specifically by adding perforations to the baffle and changing the baffle orientations, their effect on sound transmission loss was examined.

Results: The results of this study indicated that the sound transmission loss across the examined frequency range did not exhibit a consistent pattern with changes in geometric parameters. Specifically, at certain frequencies, the changes led to an increase in sound transmission loss, whereas at others, they resulted a decrease. However, in general, positioning the baffle's apex towards the muffler outlet increased the average transmission loss, while orienting the baffles’s peak towards the muffler outlet enhanced the average transmission loss, whereas adding perforations to the baffle reduced the average transmission loss.

Conclusion: Creating perforations on the baffle and changing its orientation in reactive mufflers can affect sound transmission loss and, more broadly, its acoustic performance.

Mediating influence of job burnout and job satisfaction in relationship between work stress and organizational commitment among exceptional education teachers in Baghdad, Iraq

Al Dabi MBH — 2025-04-12

Introduction: Educators in exceptional schools represent a significant research focus explored by researchers across various disciplines, primarily owing to the intense demands of their jobs and their coping strategies for such circumstances. In light of this, the present research was conducted to explore the connection between job stress and organizational commitment, focusing on the mediating effects of job satisfaction and job burnout among exceptional education teachers in Baghdad, Iraq.

Materials and Methods: The method of research employed was causal correlation research (structural equation modeling). The statistical population for the research consisted of all the exceptional education teachers from elementary schools in Baghdad, Iraq, during the spring and summer of 2024, totaling 524 individuals. Among them, 200 individuals (100 females and 100 male) were chosen as samples using the convenience sampling method. Data were collected using occupational stress questionnaires of the Health and Safety Institute of England (HSE), job burnout by Maslach, & Jackson (1996), organizational commitment by Allen and Meyer (1991), and job satisfaction evaluation by Smith et al. (1969). To analyze data, a structural equation model was used through SPSS 26 and AMOS 23 software.

Results: The results of direct effects showed that job stress significantly impacted organizational commitment, job satisfaction, and burnout (p<0.01). Additionally, both job satisfaction and job burnout significantly influenced organizational commitment (p<0.01). Examining the indirect effects revealed that both job satisfaction and job burnout played a significant mediating role in how work stress influences organizational commitment (p<0.01).

Conclusion: According to the results of this study, it is recommended that managers and policymakers in the Iraqi education system focus significantly on decreasing job stress, due to its impact on enhancing job satisfaction, fostering organizational commitment, and lowering job burnout among special education teachers. In this regard, they can take advantage of the presence and advice of organizational psychologists to recognize and address the sources of job-related stress

Effect of 8 weeks of high-intensity functional training (HIFT) on previous vascular factors and exercise enjoyment in women suffering from metabolic syndrome

Behari Kia M — 2025-04-12

Introduction: Individuals with metabolic syndrome face a higher risk of developing cardiovascular disease compared to healthy individuals, attributed to endothelial dysfunction, increased blood lipids, and insulin resistance. Despite exercise being an effective prevention method for enhancing and preventing metabolic syndrome, fewer than 23% of adults perform the minimum recommended physical activity.

Materials and Methods: In this semi-experimental research (applied, with pre-test, and post-test), 30 women diagnosed with metabolic syndrome and a body mass index ranging from 30.9 to 33 were selected and randomly divided into two groups (control and exercise). The participants underwent an 8-week training intervention, 3 sessions per week, with progressive intensity under the supervision of a trainer. Cardio metabolic markers and body composition were evaluated at the beginning and again after 8 weeks of training. Furthermore, the questionnaire on enjoyment and motivation to continue the activity was assessed following the exercise intervention. All statistical analyses were conducted at a significance level of 0.05 using SPSS software version 21.

Results: The findings indicated that 8 weeks of HIFT training led to a significant decrease in systolic and diastolic blood pressure, triglycerides, LDL, HDL, and fasting blood sugar (P=0.05). Significant changes were observed in body composition and perceived enjoyment of physical activity (P=0.05).

Conclusion: HIFT exercises lead to significant clinical improvements in the cardiovascular risk factors associated with metabolic syndrome and body composition while allowing participants to enjoy their activities and minimizing obstacles to engaging in sports. Therefore, it is recommended that sports specialists and medical doctors utilized this type of exercise as a method for the prevention and treatment of metabolic syndrome.

Analysis of accidents in a steel industry in 7 years in Iran: a case study

Alboghobeish A — 2025-04-12

Introduction: Considering the rising development of industries and technology and the resulting rise in workplace accidents and injuries, this study aimed to investigate and analyze the epidemiological events in the steel industry in Iran.

Materials and Methods: This study was a descriptive-analytical investigation conducted to investigate work-related accidents in a steel factory in Iran over a period of 7 years, from 2016 to 2022. In this study, data were collected via documentation and interviews with individuals affected by the accident or those who witnessed it. Subsequently, data analysis was performed utilizing the demographic information of the victims (age, work experience, etc.), accident type, and cause of the accident using SPSS version 22 software. Additionally, the victims’ educational background, work shifts, and the timing of the accident were analyzed.

Results: The results indicated that among 7251 workers, 130 accidents occurred over a span of7 years. The results showed that individuals with extensive work experience had the fewest accidents. A significant relationship was observed between lost work days and unsafe practices and conditions (P<0.001), with unsafe conditions exerting a more considerable influence on lost work days due to accidents. Additionally, the greatest harm to individuals resulted from impact with objects. Regarding the timing of the accidents, the highest number of accidents occurred in the fall and during the morning shift.

Conclusion: In this study, the highest number of accidents was seen in individuals with under 5 years of work experience who had previously undergone safety training. The primary factors contributing to the accident were hazardous behavior and their interaction with unsafe conditions. Therefore, ongoing basic information and training for workers based on the changing environmental conditions, alongwith routine inspections, can improve safety and reduce unsafe practices in this industry.

Predicting extra-role behaviors through job commitment, organizational loyalty, stress perception, justice perception, conscientiousness and intrinsic work motivation of faculty members in Wasit University in Iraq

Abdulridha Hussein Shihmani H — 2025-04-12

Introduction: Current research was conducted with the aim of predicting extra-role behaviors by examining job commitment, organizational loyalty, stress perception, justice perception, conscientiousness, and internal work motivation among faculty members of Wasit University in Iraq.

Materials and Methods: Research method was correlational and statistical population included all faculty members of Wasit University in summer of 2024. Out of the stated statistical population, 250 individuals were selected using convenience sampling, and a set of questionnaires included extra-role behaviors (Lee and Allen, 2002), perceptions of organizational justice (Colquitt, 2001), internal job motivation (Gagne et al., 2015)), conscientiousness (McCrae and Costa, 1992), Blau's (1993) job commitment, organizational loyalty (Kumar and Shekhar, 2012) and job stress (Cohen et al., 1964). The research data were analyzed using Pearson's correlation coefficient and multiple regression analysis via the stepwise method, utilizing SPSS software version 25.

Results: The results indicated a notable positive correlation among job commitment, organizational loyalty, perception of justice, internal motivation, and conscientiousness with extra-role behaviors, while a significant negative correlation was found between job stress perception and extra-role behaviors (p<0.01). Moreover, results from the stepwise multiple regression analysis revealed that, out of all predictor variables during the three steps, justice perception, internal motivation, and organizational loyalty could account for 45% of the variance of extra-role behaviors.

Conclusion: Based on the findings of the present study, fostering extra-role behaviors among academic staff requires a focus on providing essential platforms that enhance job commitment, promote organizational loyalty, improve perceptions of justice, boost internal motivation, encourage conscientiousness, and diminish stress.. This should be taken into consideration by the policymakers of Iraqi higher education system.

Relationship between job stress and sleep deprivation with burnout in train hoteliers

Sadra N — 2025-04-12

Introduction: Burnout refers to a decrease in an individual's ability to adapt to stressors and includes a syndrome consisting of emotional exhaustion and decreased personal success. A primary factor contributing to burnout is job stress. The job of train stewardess is one of the most stressful jobs due to the need to work in different work shifts, especially night shifts. Consequently, this study aimed to investigate the relationship between job-related stress, insufficient sleep, and burnout among Yazd-Tehran train attendants.

Materials and Methods: This study was a cross-sectional study. The research data were collected using the standard questionnaires for OSIPO job stress, burnout, and Petersburg sleep deprivation (PSQI). The Pearson and Spearman correlation method was applied using SPSS version 20 software to analyze the statistical data. The statistical population for this study comprised all the train crews of the Yazd-Tehran train. Based on the data supplied by the company’s hiring department, there were 123 individuals working on this line. Due to the small population, the sampling of this study was judgment, utilizing the Cochran formula, resulting in the selection of 90 individuals. The Cronbach's alpha method was utilized to determine both the validity and reliability of the test. Smart Pls software was used to examine the research hypotheses, and a significance level of less than 0.05 was considered.

Results: Male participants made up the majority of the sample at 68.9%. A considerable portion of the participants possessed a master's degree, making up 53.3%, whereas individuals holding a bachelor’s degree accounted for 34.5%. According to the model drawn, all paths had factor loadings greater than 0.4. The t-statistic value in this analysis was calculated for all confirmatory factor analysis relationships and greater than 1.96 for the structural model. The alpha value, Rho_A coefficient, and CR for every variables were all determined to be above 0.7, with the AVE value also evaluated to be greater than 0.5. To ensure the results, the bootstrapping test was also simulated in two cases of 500 and 800 samples, which did not change the results obtained and these paths were significant. First, descriptive results of the research variables were presented, then the validity and reliability of the measurement tool were examined using convergent and divergent validity and structural equation modeling.

Conclusion: The results indicated that job stress positively and significantly impacts job burnout and sleep deprivation. The effect of this independent variable on the dependent variable of sleep deprivation is relatively high. Sleep deprivation also has a positive and significant effect on job burnout.

Resilience relationship with effort-reward imbalance mediated by teaching emotions in elementary teachers of Taft City

Jannesar F — 2025-04-12

Introduction: The imbalance between reward and effort, characterized by the disparity between effort put in and rewards received, can be greatly affected by personal abilities and feelings. The present study aimed to investigate the relationship of resilience with Reward-Effort imbalance mediated by teaching emotions in elementary school teachers of Taft City.

Materials and Methods: The methodology used in the research was correlational along with structural equation modeling. The statistical population included all elementary school teachers in Taft City during the academic year 2020-2023, totaling 679 individuals. A sample size of 250 participants was determined, and the sampling was conducted on a voluntarily basis. The research tools included the Connor and Davidson Resilience Questionnaire (2003), Reward-Effort Imbalance (Siegrist, 2010), and Teaching Emotions (Villavicencio, 2010). Finally, data from 234 participants were analyzed using structural equation modeling through SPSS26 and AMOS24 software.

Results: The results showed that the direct effect of resilience on Reward-Effort imbalance was significant (β=0.180; P=0.029); moreover, the direct effect of resilience on teaching emotions was notable (β=0.396; P=0.001); And the direct effect of teaching emotions on Reward-Effort imbalance is also significant (p=0.211; P=0.018); additionally, the results showed that the indirect effect of resilience on Reward-Effort imbalance through the mediating influence of teaching emotions was significant (β=0.083; P=0.011) and the total effect was also significant (β_t =0.264, P=0.001).

Conclusion: In conclusion, focusing on teaching emotions within resilience training programs for elementary school teachers may help reduce Reward-Effort imbalance by regulating emotions.

Climate Change and Outdoor Workers: A Narrative Review

Asghari M — 2025-04-12

Introduction: Global warming and climate change have become one of the controversial topics that have a critical impact on human health and threaten human life. Workers, especially those working outdoors, are often the first ones exposed to the effects of climate change. The study aimed to analyze the impacts and dimensions of climate change on workers' health, investigate the factors contributing to workers' vulnerability to this phenomenon, and propose protective and control strategies.

Materials and Methods: This narrative review highlights findings from global studies on climate change and its consequences (heat stress) in occupational environments. The articles published between 2005 and 2023 were analyzed using Scopus, PubMed, and Web of Science databases, focusing on keywords such as climate change, outdoor workers, vulnerability, and heat stress.

Results: The review of various articles showed that climate change affects work settings and employees through rising ambient temperature and elevated heat stress, greater exposure to ultraviolet radiation, increased air pollution, climate-related vector-borne diseases, and other related hazards. It also encompasses risks linked to industrial shifts and the rise of new green industries such as solar and wind energy production, mental health issues (including anxiety, stress, substance abuse) as well as reducing productivity and economic burden. To evaluate the vulnerability of workers' health to climate change, three key factors are taken into account: sensitivity (the level of physical and inherent vulnerability to climate change effects), exposure (the extent and intensity of climate change-relate interactions ), and adaptive capacity (the ability of the system to cope with and recover from the effects of climate change).

Conclusion: Climate change, as a global challenge, significantly impacts various professions, particularly those in outdoor environments. The foremost consequence of climate change is global warming and the rising levels of heat stress. These changes can give rise to various health problems, from minor issues like Skin rashes to severe conditions like heatstroke. Additionally, they can impede workers' productivity, leading to decreased physical and mental performance and an increased risk of accidents. Outdoor workers must adjust to these climate changes and adopt modern, sustainable approaches to tackle upcoming challenges.