Journal of Occupational Hygiene Engineering
Year:2020 | Volume:7 | Issue:3|Papers Count:8

Background and Objective: Perforated panels are one of the most common resonant absorbers for sound control. These types of absorbers are widely used due to their adjustable mechanical properties and ease of processing. This study was conducted to investigate the acoustic properties of non-flat perforated panels in oblique angle and diffusion field using both numerical and experimental methods. Materials and Methods: To investigate the effect of surface shape on the performance of the perforated panel, three non-flat shapes were considered for the perforated panel and their absorption performance was compared with the usual shape of the perforated panel (i. e., flat) using the numerical method. Initially, the most appropriate shape was determined in terms of absorption coefficient. Afterward, the desired shape was constructed in the dimensions approved by the ISO 354 and subjected to a random incidence absorption coefficient test in the reverberation chamber. Results: The results of numerical simulation indicated that the shapes defined in this research all could improve the absorption coefficient at the middle and high frequencies. Moreover, the shape C showed a higher absorption coefficient at the lower frequencies than the flat and the two defined shapes. Based on the measurement of a random incidence absorption coefficient, the highest absorption coefficient was obtained at a frequency of 160 Hz with a value of 0. 77. These conditions were implemented in a numerical environment and the random incidence absorption coefficient was calculated according to the existing relationships. Conclusion: It can be concluded that surface shape is effective in improving the absorption performance of these types of adsorbents. The comparison of numerical and laboratory results showed the acceptable agreement of these two methods and the numerical method is capable of predicting this quantity with good accuracy.

Background and Objective: Acrylonitrile is a potential carcinogen for humans and exposure to its vapors can have a variety of adverse effects on employees in the petrochemical industry. Therefore, the present study was conducted to determine the level of exposure and assess the quantitative health risk of exposure to acrylonitrile vapors in the exposed personnel of a petrochemical complex. Materials and Methods: In this cross-sectional study, which was conducted in a petrochemical complex, a total of 45 inhaled air (3 samples per person) was sampled. Samples were collected using absorbent tubes containing activated charcoal from SKC. The samples were prepared and analyzed according to the 1601 NIOSH method using the VARIAN CP-3800 gas chromatography. Finally, the US Environmental Protection Agency (EPA) method was used to determine the level of employee exposure and the health or non-cancer risk index (HQ). Data analysis was performed using SPSS software version 25. In order to investigate the differences between different sections in terms of exposure and health risk, Kruskal-Wallis statistical test was used at a significance level of less than 0. 05. Results: The results of the present study showed that the average concentration of acrylonitrile vapors in the studied petrochemical complex is 71. 1± 122. 8 micrograms per cubic meter (0. 033± 0. 056 ppm) on average. The non-carcinogenic risk was also calculated to be 4. 04± 6. 93. It was found that 47. 6% of the subjects were within the permissible non-carcinogenic range (HQ <1) and 53. 3% of the subjects were within the allowable range (HQ> 1). Conclusion: Considering that the health risk of exposure to acrylonitrile vapors in the studied petrochemical complex was more than the recommended range (2 ppm or 4. 34 mg/m 3 ), taking engineering and management measures to control and reduce the risk levels to an acceptable level, including modification of local and general ventilation systems, as one of the main reasons for the respiratory exposure of the workers, is essential for the improvement of the situation.

Background and Objective: Musculoskeletal disorders are among the most common occupational injuries among the food factory workers. This disorder is one of the 10 injuries leading to absenteeism in the workplace. Therefore, the present study aimed to evaluate the musculoskeletal disorders caused in the workplace along with the effect of ergonomic interventions on pain relief and its relationship with job satisfaction among the workers working at the food factory. Materials and Methods: This quasi-experimental study utilized a Nordic questionnaire and quick exposure checklist to identify the prevalence of musculoskeletal disorders and assess the risk factors, respectively. Moreover, the severity of pain and work satisfaction assessment were evaluated using the visual analog scale and a Minnesota questionnaire, respectively. Furthermore, eight weeks of ergonomic interventions were applied based on the protection and health regulations of the Ministry of Labor. Independent and dependent t-tests were used to compare the intergroup and intragroup comparisons, respectively. The data were analyzed in SPSS software (version 24). Results: According to the results, the prevalence of musculoskeletal disorders was observed in the lower back (63. 39%), knee (58. 28%), wrist (33. 33%), and neck (30. 71%) regions. Moreover, the results of the statistical paired t-test showed that after eight weeks of ergonomic interventions, the pain in the lower back (P=0. 001) and knee (P=0. 003) regions was significantly reduced, followed by a significant increase in work satisfaction (P=0. 001). In addition, there was a negative significant relationship between work satisfaction and musculoskeletal disorders among the workers (P=0. 05). Conclusion: Musculoskeletal disorder had a high prevalence among the population under study. Moreover, it had a negative correlation with work satisfaction. However, ergonomic interventions had positive effects on alleviating the pain caused by work-related musculoskeletal disorders and increased work satisfaction among the workers.

Background and Objective: Human capital is the main axis of sustainable development in leading organizations. The HSE management system helps organizations to build a safe and accident-free environment using integrated and synergistic arrangement of human capital and all other resources so that its performance directly affects the overall performance of the organizations. This study aimed to develop an HSE competency management model for the organizational positions affecting HSE system performance in a power plant construction company. Materials and Methods: This study was conducted based on a descriptivesurvey research approach. After the evaluation of the theoretical and experimental principles, key organizational criteria affecting HSE performance and organizational positions in the company under study were determined based on these criteria using a questionnaire and interviews. Subsequently, the selected organizational position were prioritized based on their impact on HSE system performance using the Technique for Order Performance by Similarity to Ideal Solution. In the next stage, the components of forming a model for a case study were determined considering the nature of the selected organizational positions, investigation of the models and reference standards, as well as the experts’ views. Results: In total, 30 organizational positions were identified as key positions influencing HSE system performance regarding the degree of effectiveness in the performance of the system. Moreover, five components, including knowledge, skill, competency, perception and attitude, as well as responsibilities and authorities, were determined as the components of the competency management model. Conclusion: According to the findings, it is necessary to have competency, skills, required abilities and knowledge along with appropriate perception and attitude, as well as responsibilities and authorities, to successfully perform a job in different and changing situations or during an emergency.

Background and Objective: Pyrethroids (i. e., deltamethrin) are one of the most common insecticides that are used extensively in agriculture to control the insects. Oxidative stress is one of the main mechanisms of pesticides, including deltamethrin, in developing toxicity. Many plants contain high levels of antioxidants that can play a role in absorbing and neutralizing free radicals. The current study aimed to assess the oxidative and protective role of Salvia officinalis extract (Sage) in alleviating the detrimental effect of deltamethrin and the induced oxidative stress on the kidneys of the male rats. Materials and Methods: In total, 30 Wistar rats were randomly divided into five groups of six animals per group. Group 1 was considered the control group, and group II received deltamethrin (15mg/kg). Moreover, group III received deltamethrin and Salvia officinalis extract (100mg/kg), and group IV received deltamethrin (15mg/kg) and Salvia officinalis extract (200mg/kg). Group V received Salvia officinalis extract (100mg/kg). The treatment was extended for one month, and subsequently, the kidney tissues of all rats were evaluated to assess the malondialdehyde and glutathione peroxidase levels using appropriate assessment kits. It is worth mentioning that histopathological changes were also investigated in this study. Results: The results showed that Salvia extract significantly reduced the toxic effects of deltamethrin in the kidneys of the rats. Moreover, Salvia extract significantly reduced malondialdehyde levels and improved glutathione peroxidase activity. The results of kidney tissue pathology also confirmed Salvia’ s protective effect against deltamethrin. Conclusion: The protective effect of Salvia extract can be due to phenolic compounds and antioxidant activities, which can be used as an effective factor in the prevention and improvement of the toxic effects of deltamethrin.

Background and Objective: Nowadays, musculoskeletal disorders are one of the most important occupational health issues which are prevalent in almost all occupations. This study aimed to evaluate the musculoskeletal disorders and their related factors in housewives, Yazd Province, Iran. Materials and Methods: This cross-sectional study was carried out on 396 housewives in Yazd Province, Iran, during 2019. The data were collected using the Nordic questionnaire in person. Moreover, this questionnaire and Rapid Entire Body Assessment Method were utilized to investigate the prevalence of musculoskeletal disorders and assess the body ergonomic posture at work, respectively. The data were analyzed in SPSS software (version 22) using the independent t-test and ANOVA. Results: The most prevalent musculoskeletal disorders in the housewives were observed in the lumbar region (67%), knee (53%), and neck (43%). Moreover, the prevalence of musculoskeletal disorders in some body areas increased as a result of an increase in the number of children, as well as decline of the welfare status, and the use of assistive devices at home. It should be mentioned that the musculoskeletal disorders had a significant impact on the calf and ankle. Conclusion: The results showed a high prevalence rate of musculoskeletal disorders in the studied population. Moreover, age, marriage age, height, weight, number of pregnancies and children, education level, welfare and residential status, daily exercises, used devices, elevator, and staircase played a significant role in the outbreak of musculoskeletal disorders. Considering the large population of housewives, it is recommended that more extensive studies be conducted on these disorders in this group.

Background and Objective: Noise absorber is considered the main method for noise control in propagation path. This study aimed to evaluate the effectiveness of environmental noise control using noise absorbers at a press workshop based on the recommended ISO 11690 method. Materials and Methods: This experimental study was performed at a press workshop of a metal structure company. The environmental noise control was established by the installation of a metal mesh using perforated gypsum tiles with a layer of stone wool at the ceiling. Afterward, the evaluation was conducted based on the ISO 11690 method which included the determination of the rate of noise reduction measurement from an omnidirectional source based on the distance doubling. Moreover, the noise level was measured at the defined distance from an artificial noise source along with the length of the workshop. Results: The environmental noise was reduced approximately (3 to 4 dB) after the installation of an acoustic ceiling. Furthermore, the environmental noise reduction was considerable at the frequency spectrum of 2000 Hz, 4000 Hz, and 8000 Hz. At the press workshop, the noise was reduced 4 dB based on the distance doubling from an omnidirectional source indicating a reduction in the surface noise reflections of the press workshop Conclusion: The efficiency of the environmental noise control was determined at high accuracy using noise reduction curve from an omnidirectional source, comparison of the results with the recommended optimal conditions, and sound propagation pattern in the free field of the sound.

Background and Objective: The most logical decision to take into account when manufacturing a device is the application of the ergonomic principles in the design stage. One of the main goals of computer application in ergonomics is to develop a tool that allows the product to be evaluated at the beginning of the design process. This study aimed to evaluate the ergonomics of a powder paint spraying station and present a new design using Computer Aided Three-dimensional Interactive Application (CATIA) software. Materials and Methods: This study was conducted on a paint spraying unit at a home appliance manufacturing factory. The digital model of the posture with the most deviation from the normal posture was simulated in the CATIA software. After evaluation by the Rapid Upper Limb Assessment (RULA) method, the biomechanical analysis was performed on the human model. Finally, based on the results of the RULA, ergonomic interventions were performed in the software, and the new workstation was re-evaluated in this study. Results: The final score of evaluating the color spray posture showed that the posture was at level four. This indicated the necessity of corrective measures and immediate changes. In this posture, the position of the forearm, muscles, wrists, arms, legs, upper body, and neck was inappropriate. Proposed interventions included the change of seat design and the weight adjustment of the spray gun. Conclusion: The results show that musculoskeletal problems can be significantly resolved by focusing on the organs that are under pressure and providing an ergonomic design prepared by CATIA software to reduce the pressure.