Journal of Health and Safety at Work

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Introduction: The accurate evaluation of error probability and risk is important. Accordingly, this Comparative study was conducted to evaluate the risk of human error in emergency situations using SLIM and Fuzzy SLIM techniques in fierfighting tasks.
Material and Methods: This cross-sectional and descriptive-analytical study was conducted among 12, using Fuzzy SLIM and SLIM techniques. 39 sub-tasks were studied in 4 phases (Awareness, Evaluation, Egress and Recovery). Considering the advantages of the Fuzzy SLIM method, fuzzy logic was used in weighting of performance shaping factors (PSF). Excel software was used to calculate the probability of error. Also, correlation and kappa statistical tests were used for data analysis in SPSS software.
Results: The mean and standard deviation of human error probability in different sub-tasks of firefighting in SLIM and Fuzzy SLIM methods were 0.095357 ± 0.026193 and 0.06490 ± 0.051748, respectivly. In 48.7 percent of the sub-tasks, the probability category of human error and the assessed risk were the same; however, in 89.7 percent of the sub-tasks, the estimated level of risk was the same in both methods. Correlation test showed that the correlation coefficient of error probability values between the two methods was 0.32, which indicated a moderate correlation in this regard. Additionally, the results of kappa statistical test for the estimated level of risk showed that there is a high agreement between Fuzzy SLIM and SLIM (P value <0.05).
Conclusion: The results of the study indicated meaningful agreement and a moderate correlation between Fuzzy SLIM and SLIM. Therefore, due to the relatively high accuracy of Fuzzy logic methods, and also the long steps of implementing the SLIM method, the Fuzzy SLIM method can be a good alternative to this method.

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Introduction: Lifting loads in awkward postures is a main cause of low back musculoskeletal disorders. In this context, researchers have used various indicators to determine the relationship between biomechanical variables and the risk of these disorders. This study aimed to investigate the correlation between plantar pressure distribution and the values of UTAH back-compressive forces (BCF) and lifting index (LI) during symmetrical load-lifting tasks.
Material and Methods: Thirteen healthy men, aged 25 to 35, took part in this study. The participants were instructed to symmetrically lift loads weighing 7.5 kg and 15 kg in 15 different postures, considering three horizontal distances (A, B, C) and five different heights (1-5). Pressure on the foot soles was recorded using 16 force-sensitive resistors (FSR) corresponding to eight anatomical areas on each foot. The BCF and LI were also calculated using the UTAH method and the NIOSH equation, respectively. Statistical analysis was performed using SPSS (version 21) software.
Results: Based on the results, when the load was closest to the body (A1-A5), the highest pressure was recorded in the heel and the 4th and 5th metatarsal of both feet. In lifting a load of 15 kg in the A2, B1, B2, C1, C2 postures and lifting a load of 7.5 kg in the C2 posture, the average BCF exceeded 700 pounds. The LI was greater than 1 for specific postures (B1, B2, B4, B5, C1-C5) at 15 kg and (C1, C2, C4, C5) at 7.5 kg load-lifting. During the 7.5 kg and 15 kg load-lifting, there was a significant correlation between the plantar pressure and the values of LI and UTAH (p-values < 0.05) in most postures.
Conclusion: The results showed a significant correlation between plantar pressure distribution and load-lifting postures. The study findings, which identify risk levels associated with lifting postures, lay the groundwork for future research aimed at categorizing safe and unsafe plantar pressure patterns.

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Introduction: One of the ways to produce electricity in power plants is to use gas turbines and generators. Due to the use of methane gas as the fuel of the burners and the high rotation speed, this equipment has a high DOW index level, therefore, if the hazardous conditions in the gas turbine are not controlled by the safety instrumented system and the process is not directed to a safe state, Catastrophic events will occur such as fire and explosion and damage to property and people as well as interruption of the power generation process will happen in the long term, so gas turbine safety instrumentation systems can be considered as “critical safety systems”. Therefore, the reliability and availability of their function should be evaluated. The purpose of this research is to determine and verify the safety integrity level (SIL) related to the safety instrumented function (SIF) of the gas turbine and generator in a combined cycle power plant.
Material and Methods: In this study, the safety integrity level was determined by using two methods, Calibrated Risk Graph (CRG) and Independent Protection Layer Analysis (LOPA), and to verify the safety integrity level, the requirements related to random hardware failure, hardware failure tolerance, and systematic capability are considered according to IEC 61511 and IEC 61508 standards.
Results: The results of a case study in gas turbine and generator showed that the LOPA method is more quantitative than CRG and provides more details of independent protective layers, so it is a more suitable method for determining SIL. The SIL verification results show the SIL2 level, closer to the LOPA results.
Conclusion: The obtained results show that the function of the studied gas turbine safety instrumentation system has a suitable level of reliability and availability and is well responsive to risky conditions and possible deviations. The present approach helps safety engineers and instrumentation engineers to calculate the reliability and availability of the Function of the safety instrumentation systems of their process equipment and ensure its acceptability or not.

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Introduction: Protection of the respiratory system has been a vital, and for this purpose, various solutions have been proposed, including the use of masks. One of the most important parameters to measure the effectiveness of the mask against the penetration of microbial agents. The present study was conducted with the aim of evaluating the bacterial and particle filtration of medical masks.
Material and Methods: To assess bacterial performance, the national standard 6138, compliant with EN14683, and Type I medical masks were utilized. Staphylococcus aureus bacterial suspension was prepared and passed through the mask using a nebulizer and through an impactor with a flow rate of 28.3 l/min. Plates containing soy agar were placed in the impactor. Subsequently, all plates were incubated, and the bacterial filtration efficiency (BFE) of the masks was determined by counting the bacterial colonies that passed through the mask’s media as a percentage of the total bacteria. It is worth noting that the pressure drop and particle filtration efficiency were also determined for all masks
Results: Based on the results of the particle removal performance for the particle size of 3 µ, the masks were categorized into three groups with efficiency above 99%, above 95% and 90%. According to the standard, all masks had an acceptable pressure drop below 40 Pa. The acceptable bacterial filtration rate for type I masks should be above 95%. The results showed that type A and B masks have an acceptable bacterial filtration rate and there is a significant correlation between the types of masks examined in terms of bacterial and particle efficiency.
Conclusion: The results showed that different types of masks under investigation have significant differences in terms of particle capture efficiency and bacterial filtration performance. In addition, there is a significant correlation between bacterial and particle filtration efficiency.
 

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Introduction: Obesity and overweight are major global health challenges. One of the bad effects of noise that has been recently expressed is the effect of noise on obesity. This study aimed to investigate the effect of high-frequency noise exposure on obesity, food intake, and abdominal visceral fat in adult male guinea pigs.
Material and Methods: The animals in this study were 24 adult male guinea pigs randomly divided into 3 groups (control and two case groups). Each case group was separately exposed to high- frequency white noise with sound pressure levels in 65 dB and 85 dB for 5 days per week in 30 days. The food intake was measured daily. The weight of animals was measured at the start and on days 6, 12, 18, 24, and at the end of exposure period. The abdominal visceral fat was extracted and weighted at the end of the study period. The data were assessed using SPSS V.22 software.
Results: ANOVA analysis showed that exposure to high-frequency noise at 65dB and 85dB had a significant effect on weight gain, food intake, and abdominal visceral fat weight (P-value< 0.05) which in the group exposed to the noise with 65 dB was more than other groups.
Conclusion: Based on this study, exposure to high-frequency noise may be an effective factor in obesity and increasing abdominal visceral fat. Further studies are needed to investigate the mechanism affecting weight status following noise exposure.
 

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Introduction: Improving health and the environment is one of the components of development, social welfare, and economic growth. Another influential factor in increasing health costs and reducing social welfare is work-related accidents and diseases, which impose high costs on individuals, industries, and the national economies of countries. Therefore, using multi-criteria decision-making methods, the present study provided a conceptual model to identify and rank work-related diseases’ environmental and health costs.
Material and Methods: The present study was conducted in 2023. A classification model for the economic evaluation of environmental and health costs of occupational diseases was developed to achieve the study’s aim. In the current research, the Delphi method was used to identify health and environmental criteria, and the Analytic Network Process (ANP) was used to weight the sub-criteria. Finally, the cost of health and the environment was estimated based on the available information. Naft Tehran Hospital (NSHT) was also selected as a case study site.
Results: The results showed that the drug and medical equipment cost factor, with a weight of 0.312 in the treatment sector, and the particular and infectious waste cost factor, with a weight of 0.085, were the most critical factors in the economic evaluation. Also, the parametric model results showed that 99.84% of the total costs are related to health costs, and 0.16% are related to environmental costs. In general, the results of this research showed that 61.3% of the costs of the health sector are related to the two sectors of medicine and medical equipment and the cost of service personnel, and 91.7% of the costs of the environmental sector are related to wastewater treatment and the cost of electricity consumption.
Conclusion: This study presented a semi-quantitative model to estimate health and environmental costs caused by occupational diseases. The results can create a novel scientific insight into implementing control measures using the optimal point of cost-benefit parameters. Implementing this integrated model can be a practical and effective step in allocating resources and prioritizing interventions.
 

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Introduction: Considering the abundance and the large number of workers employed in micro and small industrial workshops in Iran and the importance of workers’ health, the present study aimed to investigate the mediating role of chronic fatigue in the relationship between mental workload and work ability with cognitive failure using path analysis.
Material and Methods: This study was conducted using a cross-sectional design on a sample of workers employed in micro and small industrial workshops in the city of Eghlid. Data were collected utilizing various measures, including demographic and occupational information questionnaires, the NASA Task Load Index (NASA-TLX), the Work Ability Index (WAI), and questionnaires for chronic fatigue and cognitive failure. The correlation test and path analysis modeling were used in SPSS (version 24) and AMOS softwares to investigate the relationship between variables.
Results: The mean scores of mental workload, work ability, chronic fatigue, and cognitive failure  
were 69.63, 35.20, 15.58, and 53.30, respectively. The values of the goodness of fit indices lead to  
the confirmation of the conceptual model by the research data. Also, based on the findings of the path analysis, the current research model has a good fit (CFI=1.00, GFI=0.998, NFI=0.999, AGFI=0.98 and RMSEA=0.003(0.00,0.169)).
Conclusion: The path analysis results indicate that chronic fatigue plays a significant mediating role  
in the relationship between mental workload and work ability with cognitive failure. A better understanding of the mediating mechanisms and complex effects of these relationships can contribute to improving the management of chronic fatigue and enhancing cognitive performance in the workplace.
 

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Introduction: Driving has various harmful factors due to its nature, which affect drivers’ health directly and indirectly. Therefore, it is necessary to know the situation and prevalence of these factors in drivers to implement preventive measures.
Material and Methods: This cross-sectional study is a part of a cohort study conducted (2016 to 2018) among the professional drivers of Shahroud, Iran. Data related to background information, blood pressure, height, weight, waist circumference, body mass index, blood factors, hearing loss (dB), respiratory performance indicators, sleep disorders, and accidents were collected from the participants with standard tools and methods.
Results: This study examined 1461 male professional drivers with an average age of 37.30±6.96 years. A total of 426 participants had metabolic syndrome. 797 and 942 people had different degrees of hearing loss, respectively, in the right and left ear. About 129 people had obstructive sleep apnea, and 1330 people had insomnia. Investigations showed that 351 drivers had at least one accident.
Conclusion: This study showed the prevalence of health risk factors in professional drivers at the examined time point. Considering the vital role of drivers in transportation and the country’s economy, it seems necessary to pay more attention to the health of this occupational group. Regular health screening, healthy lifestyle training, improvement of working conditions, and stress management are some interventions that can effectively improve drivers’ health.
 

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Introduction: A wood-wool cement panel (WWCP) is wood wool combined with Portland cement mortar. This environmentally friendly acoustic material can be used as a thermal insulator and fire-resistance material with desired mechanical properties. This study aimed to determine the mechanism by which WWCP absorbs sound and the effect of production and application parameters on absorption
Material and Methods: The samples were prepared from poplar wood wool and white Portland cement as a binder in two Cement Fiber Ratios (CFR), namely 2:0.7 and 2:0.95, with bulk densities of 400, 500, and 600 Kg/m3 and thicknesses of 2 and 4 cm. Three layers of backing: air, polyurethane foam, and glass wool were examined separately. Acoustic absorption coefficient was measured using an impedance tube based on ISO 10534-2.
Results: The highest increase in the average absorption coefficient due to the increase in thickness was observed for the sample with a density of 400 kg/m3 and CFR = 2: 0.95, equal to 0.3. Increasing the bulk density to 500 kg/m3 for most samples and in the high-frequency range led to rising absorption efficiency. The optimal backing effect was due to the placement of 4 cm of polyurethane foam behind the sample, which in both thicknesses led to an absorption peak with an absorption coefficient higher than 0.95 at frequencies between 400 and 500 Hz. Selected samples showed that painting WWCPs led to a limited drop in absorption coefficients at high frequencies, comparing the before and after painting results with oil-based paints.
Conclusion: Tuning the absorption frequencies of these absorbers can be achieved by altering factors such as the thickness or density. It has been demonstrated that the effects of thickness and bulk density on the sound absorption of WWCP are related to each other. Concerning the CFR values, increasing the density did not significantly affect absorption in the two frequency ranges.

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Introduction: One of the questions that always arises in the minds of researchers, especially young researchers, is what pattern the progress of science follows in their field of expertise and what is the direction of the studies. The purpose of this study is to analyze the content of the studies published from 2011 to 2022 in Persian scientific journals in the field of workplace safety and determine the direction and scientific process of studies in this field.
Material and Methods: All the studies published from the years 2011 to 2022 in the Persian scientific research journals ”Iran Occupational Health”, “Occupational Health and Safety”, “Occupational Health Engineering”, ”Iranian Journal of Ergonomics”, “Occupational Medicine” and “Occupational Health and Health Promotion” were gathered using census method from the websites of the journals. In total, 595 published articles were categorized according to the thematic codes determined by the opinion of experts, the theme of “risk analysis, assessment, and risk management” had the highest percentage of frequency (18.66 percent), while the theme of “safety application in other industries or specific workplaces” had the lowest frequency of percentage (0.34 percent). Approximately 50 percent of the variance of the published studies explained the themes of “risk analysis, risk assessment, and management”, “inspection, analysis and modeling of accidents”, “human error and safety”, “social, organizational factors, culture, safety climate, and behavior-based safety”.
Conclusion: The existing trends emphasize the importance of learning lessons from accidents as a reactive approach and risk management, human factors, and behavioral aspects in safety interventions as a preventive approach. The research development of the country’s safety at the workplace should be further improved with new policies in different fields while taking advantage of international scientific advances on the specific functions and challenges of the country and with a problem-oriented approach.