Journal of Health and Safety at Work

Reliability Assessment of Fixed Foam Systems of Storage Tank Based on Fuzzy Fault Tree Analysis

Mostafa Mirzaei Aliabadi

Introduction: Risk assessment is a scale for predicting reliability and can manage interactions between components and process variables. Moreover, the reliability of one component or barrier affects the overall risk of the system. Being one of the most critical safety barriers of the storage tank, the failures of Fixed Foam Systems (FFS) on demand can result in severe consequences. FFS, is of grave importance in decreasing the risks associated with fires and damages.
Material and Methods: This study aims to determine the probability of root causes related to FFS failure through Fuzzy Fault Tree Analysis (FFTA) to estimate system reliability. In conventional fault tree analysis, accurate data is usually used to assess the failure probability of basic events. Therefore, the introduced approaches were employed to quantify failure probabilities and uncertainty handling. Finally, system reliability was estimated according to the failure probability of the top event.
Results: The findings showed that 13 baseline events involved FFS performance. According to the results, failures of cable path and detection system (or resistance temperature detectors), set the activation switch (multi-position) incorrectly, and foam makers not continuously running are the three most critical basic events influencing the reliability of fixed foam systems. In addition, this paper estimated the system reliability at 0.8470.
Conclusion: The results showed that the FFTA could be used in matters such as reliability evaluation failure and risk assessment using experts’ judgment. This paper can also show the adaptation of the fuzzy approach to assess the failure probability of the basic event in the fault tree analysis (FTA).

A Survey on Ergonomic Usability of a Website of Educational Management System and an Examination of the Influential Factors of a University from Students’ Viewpoint

Shirazeh Arghami

Introduction: Usability is a criterion that indicates a product’s applicability and ease of use. A usable product allows the user to perform a task correctly and quickly, preventing errors and fatigue. The present study aimed to determine the ergonomic usability of the Zanjan University of Medical Sciences website of educational management system from the students’ viewpoint in 2019 and 2020.
Material and Methods: This cross-sectional study evaluated the usability of one of the websites for educational management systems using a standard questionnaire. The study examined the utility of web-based applications in the research processes automation field. The questionnaire was embedded in Google Forms and emailed to Zanjan University of Medical Sciences students, 404 of which returned. The data were analyzed with a 0.05 confidence level using SPSS software version 16.
Results: The 404 participants’ data showed that among the questionnaire nine factors, the highest and intermediate-range mean were for “Ease of Use” at 19 and 4 and for “Ease of Learning” at 18 and 4. Moreover, they were 13 and 3 for “System Capabilities,” 13 and 2 for “System Usability,” and 10 and 2 for “User Satisfaction.” In addition, “Errors Management” received 10 and 2, “Display” 10 and 2, “System Terms and Information” 8 and 2, and “User Environment Personalization” 5.5 and 3 as their highest and intermediate-range mean, respectively. Most questionnaires did not differ significantly depending on the age variable, meaning that different age groups had similar answers to most factors. The two sexes showed a significant difference in the responses to the “Usefulness of the System,” “Ease of Learning,” and “Display.” A significant difference for other factors was found in examining the relationship between educational level and the questionnaire factors. However, the “Error Management” and “Display” factors did not significantly differ, considering the educational levels.
Conclusion: The results showed that more attention should be paid to ease of use and learning in re-designing this website. However, it is necessary to consider all factors affecting usability.

Sound Absorption of Wood-Wool Cement Absorbers

Mohammad Reza Monazzam

Introduction: Wood-Wool Cement Panels (WWCPs) are environmentally friendly sound absorbers also used as heat, energy, and moisture insulators. WWCPs have suitable mechanical properties due to using Portland cement and wood strands as raw materials. In this study, the acoustic performance of WWCP absorbents will be investigated.
Material and Methods: The mixed raw materials were molded under pressure through a hydraulic press to fabricate the WWCP samples. Samples were demolded after 24 hours. Samples were created with two thicknesses of 2 and 4 cm and three bulk densities of 400, 500, and 600 kg/m3 to examine the impact of thickness and bulk density on the acoustic absorption coefficient. The sound absorption coefficients were determined as a function of frequency for two frequency ranges: low (63-500 Hz) and high (630-6300 Hz).
Results: In the low-frequency range, increasing the thickness from 2 to 4 cm increased the absorption coefficient at 500 Hz by 0.16 and 0.23 for densities of 400 and 500 kg/m3, respectively. Increasing the thickness added an absorption peak and increased the value of these absorption peaks to 0.9 in the high-frequency range. When the bulk density of the 4-cm-thick samples increased from 400 to 600 kg/m3, the low-frequency absorption peak increased by 0.33. In the high-frequency range, the same density change increased the absorption peak by 0.26 for the 2-cm-thick sample.
Conclusion: Increasing the thickness of WWCP improves both its high- and low-frequency acoustic absorption coefficients. In addition, increasing the bulk density to approximately 500 kg/m3 boosts the sound absorption efficiency in both frequency ranges.

Fabrication of PET Nanofibers Media by Electrospinning Method and Determining its Efficiency in Removing Submicron and Micron Particle Contaminants from Air

Farideh Golbabaei

Introduction: In recent years, the manufacture of air purification media, especially nanofiber filters using polymeric materials and the electrospinning method, has received much attention in air pollution control. The production of high-performance media and low-pressure drops is an important issue in air filtration. This study aimed to investigate the feasibility of fabricating electrospinning polyethylene terephthalate (PET) media to abduct submicron and micron particles from the air stream.
Material and Methods: To determine the optimal device conditions in the manufacture of PET media, different weight percentages of a PET polymer solution in a mixture of trifluoroacetic acid and dichloromethane solvents (70:30) were first prepared in a pilot study, and various parameters of the electrospinning device were examined and analyzed along with performing the electrospinning process. The surface and morphological characteristics of the media were evaluated using SEM. The pressure drop and efficiency of particle trapping were assessed using a mask and media pressure by a pressure drop test device.
Results: The optimal electrospinning conditions of the PET polymer solution were obtained at a concentration of 20%. The average diameter of nanofibers PET was 163 ± 600 nm with a pressure drop of 26.33 ± 5.5 pa, and average efficiencies of 97.42 ± 1.67% and 99.85 ± 0.21 were obtained for submicron and micron particles, respectively, with a quality factor (QF) value of 0.1740.
Conclusion: The produced media can abduct and remove particles from the air stream for submicron and micron particles in ranges of 96-99% and 99-100%, respectively, with an average pressure drop of 26.33±5.5 pa.

Developing a Method for Evaluating Workplace Accidents: Fault Analysis Method (FAM)

Iraj Mohammadfam

Introduction: Occupational accidents are one of the most important risk factors for developing countries. In addition to designing preventive measures to prevent accidents, comprehensive research of accidents is considered as an undeniable necessity to reduce the risk of accidents. Thus, the first step is to find the root causes of their occurrence, which will certainly be possible with the use of appropriate techniques.
Material and Methods: In this study, first, the appropriate criteria for designing the accident analysis method were collected. In the second step, commonly used techniques were collected through known databases. In the third step, the collected techniques were scaled based on the selected criteria using the TOPSIS method, and ultimately, the new method (FAM) was developed. Finally, by analyzing three different accidents with the developed technique and four other common techniques, as well as using the ANP method, the developed technique was tested and confirmed.
Results: Based on the studies conducted to identify appropriate criteria for comparing accident analysis techniques, finally 6 criteria were selected for to be used in the study process. According to the findings, the FAM method with a normal final weight of 0.2684 was considered the priority in occupational accident analysis.
Conclusion: The output of this study was the introduction of the FAM technique. Using the strengths of the four techniques and covering their weaknesses, this technique can help identify and determine the causes of accidents graphically, systematically, and by minimizing the work attitude of analysts at three levels.

Validity and Reliability of the Persian Version of the Computer Vision Syndrome Questionnaire

Yahya Rasoulzadeh

Introduction: Computer vision syndrome (CVS) is one of the most common health concerns associated with the extensive use of computers, particularly in the working environment. Since recent studies have shown the high prevalence of CVS, it is necessary to have an appropriate tool for assessing this prevalence. The present research aims to translate the CVS questionnaire and analyze its validity and reliability and assess the incidence of this condition among the staff members at Tabriz University of Medical Sciences.
Material and Methods: The translation of the main questionnaire into the Persian version was carried out in three steps. Two coefficients including the content validity ratio (CVR) and the content validity index (CVI) were used to evaluate the content validity of the questionnaire. The reliability of the questionnaire was examined using two methods including internal consistency (Cronbach’s alpha) and test-retest. In total, 240 participants were asked to fulfill the questionnaire in order to investigate the prevalence rate of CVS among the staff members of Tabriz University of Medical Sciences. After removing the ineligible ones, 219 questionnaires were examined.
Results: The internal consistency coefficient and Cronbach’s alpha coefficient were 0.91 and 0.89, respectively. Out of a total of 102 women and 117 men, only 19 women and 21 men did not have CVS. Among the studied symptoms, eye redness (78.1%), burning (76.7%), and headache (74%) were the most prevalent in the statistical population. No significant relationship was observed between the final score of CVS and gender.
Conclusion: In terms of validity and reliability, the questionnaire was found to be satisfactory. The prevalence of CVS among the staff members of Tabriz University of Medical Sciences was high (81%). To determine the etiologies, further research is needed.

Fire Risk Analysis in a Student Dormitory Using Fire Risk Index Method for Multistorey Apartment Buildings in 2021: A Case Study

Vida Zaroushani

Introduction: This study quantitatively analyzed the fire risk using the Fire Risk Index Method: Multistorey Apartment Buildings (FRIM-MAB) method, considering the importance of fire safety in student dormitories as human gathering centers and previous limited studies.
Material and Methods: This descriptive-analytical study was conducted on 17 sections of the Qazvin University of Medical Sciences student dormitory in 2021. This study used the FRIM-MAB version 2.1. In this method, 17 parameters and their sub-parameters affecting the fire risk index were determined and weighted. Consequently, the studied dormitory was also inspected, the weighted degree of each parameter was computed, and the fire risk index for each section, which ranged between 1 and 5, was determined.
Results: The average fire risk index of the dormitory building at the time of the study was 2.37. The laundry room received the lowest risk index (1.69), while the computer site received the highest risk index (2.7). The results indicated that the most effective parameters causing fire risk were related to “compartmentation” (12 frequency items), “linings in the apartment” (4 frequency items), and “escape routes” (1 frequency item). These parameters contributed more than 42% to create the risk index for the dormitory’s most dangerous areas.
Conclusion: The FRIM-MAB method is a suitable quantitative and indexing fire risk assessment method for student dormitory buildings, and it is a quick, inexpensive, and effective screening and ranking tool. Periodically evaluating the dormitory’s fire risk and, if necessary, improving the environment is essential. In the present study, compartmentation, linings in the apartment, and escape routes were the most effective parameters in fire risk of the studied dormitory.

Developing a Risk Assessment Model for Respiratory Exposure to Toxic Chemical pollutants in one of gas refineries in South Pars using a Combination of AERMOD and SQRA Methods

Seyed Saeed Keykhosravi

Introduction: Nowadays, air pollution is now considered to be the largest environmental health threat. This study was conducted with the aim of determining occupational exposure to chemical pollutants, including sulfur dioxide (SO2) and hydrogen sulfide (H2S) and assessing the health risk of exposure to these compounds using a combination of AERMOD and SQRA methods.
Material and Methods: The present study is considered as a descriptive-analytical and cross-sectional research, which was conducted in 2002 in one of the gas air refineries of South Pars in the Persian Gulf region, in such a way that the amount of emissions coming out of refinery chimneys was measured by the Testo 350- XL. AERMOD model was used to simulate the dispersion of H2S and SO2 chemical pollutants. Respiratory exposure and health risk assessment of refinery personnel and nearby residents were performed using the recommended method by the Singapore Occupational Health Services Pte Ltd.
Results: Hydrogen sulfide and sulfur dioxide were introduced as the most dangerous chemicals. According to the results, the highest risk value for sulfur dioxide among the exposure groups was related to the sulfur recovery unit (SRU), the west side of the Train Gas unit and the gate pass building of the refinery, and the highest risk values for sulfur dioxide among the exposure groups were related to the HSE building, security door, fire stations building, tanks, steam generating unit, west side of Train Gas unit, dining hall and gate pass building of the refinery. Hydrogen sulfide obtained a low to medium risk level, and sulfur dioxide a low to high risk level in terms of frequency.
Conclusion: This model can be considered as a suitable and quick solution in the superior management of the concentration of pollutants and also a promising solution in order to increase the ability of decision makers to assess the health risk of industries’ personnel. Also, ensuring quality monitoring results and reducing sampling costs are discussed.

Mental Workload and Cognitive Failures Assessment of Nurses During the Period of the Covid-19 outbreak and Its Relationship with the Occurrence of Unsafe Behaviors in Public Hospitals of Guilan Province in 2019-2020

Abdolhossein Emami Sigaroudi

Introduction: Nurses are under the influence of stressful factors and high work pressure, which increases nursing errors. One factor affecting nurses’ behavior and performance is the mental workload and cognitive failures. This research has investigated the mental workload and cognitive failures in two groups of nurses with and without unsafe behaviors during the outbreak of Covid-19.
Material and Methods: This case-control study was conducted on 312 nurses during the severe period of the Covid-19 outbreak through the public hospitals in Guilan province. Sampling was performed by selecting 104 nurses in the case group (with unsafe behavior) and 208 nurses in the control group (with safe behavior) using the full count method. The data collection tool is a three-part questionnaire including demographic information, the mental workload (NASA-TLX) questionnaire, and the occupational cognitive failures questionnaire. The incidence of needle stick as a consequence of unsafe behavior was used as a criterion.
Results: The results have shown that the workload in this research was 63.96±18.26, and the total score of cognitive failures was 59.1±13.9. There was no statistically significant difference between the two groups of nurses with and without unsafe behaviors (P>0.05). Still, there was a significant correlation between the total mental workload score in all areas and the total score of cognitive failures in the group of nurses with and without unsafe behaviors (p=0.001, r=0.225).
Conclusion: According to the results, the perceived mental workload is high for the nursing job. Despite of positive correlation between mental workload and cognitive failures, it can be mentioned that there are two-way interactions through their dimensions. Therefore, the nursing job requires adopting optimal engineering and management strategies to reduce the workload.

Using a Safety Management Approach to Investigate Predictors of Adopting Preventative Behaviors in Drowning Trauma among Students

Leila Keikavoosi-Arani

Introduction: Drowning is one of the most prevalent accidents in aquatic environments. Although drowning has been noticed by healthcare policymakers in the world today, the issue of drowning has been neglected in the safety management of students. This research was conducted with the aim of investigating the predictors of adopting preventive behaviors from drowning trauma among students in the west of Tehran city with the approach of safety management.
Material and Methods: This study was descriptive-analytical (cross-sectional). The statistical population of this research included all parents of students who were studying in the first grade of the selected public schools in West of Tehran city in the academic year of 2021-2022 (N=3000). The random convenience sampling was used and 340 parents participated in this study. The data collection tool was a researcher-made questionnaire with a new approach to safety management (preventing accidents by doing preventive behaviors) based on a protection motivation model (preventive behavior model), of which reliability and validity were checked. Data analysis was done using SPSS 26 software and Pearson correlation test and linear regression.
Results: The constructs of the protection motivation model explained 67% of the variance of the behavioral intention of protection motivation and 69.7% students had no history of taking swimming classes. The highest correlation was between behavior and perceived costs (r=-0.579 and P<0.01) and 237 students (69.7%) had never exhibited preventive behaviors of learning swimming techniques or gaining swimming abilities from professional swimming coaches.
Conclusion: A significant relationship between the most constructs of the protection motivation model by performing drowning prevention behaviors, as well as the strongest correlation between preventive behaviors and perceived cost structure, emphasizes the design of free educational programs to increase students’ knowledge and motivation in the field of drowning prevention behaviors.

A Review of the Studies on Driver Drowsiness Detection Sensors and Proposing Hybrid Diagnostic Methods and Efficient Model Design

Mohsen Poursadeqiyan

Introduction: In recent years, driver’s drowsiness has been one of the leading causes of road accidents, which can lead to physical injuries, death, and significant economic losses. Statistics show that an efficient system is needed to detect the driver’s drowsiness, that gives the necessary warning before an unfortunate event occurs. Therefore, this review study was conducted to investigate the studies on driver’s drowsiness sensors and to present a combination of diagnostic methods and an efficient model design.
Material and Methods: This narrative review study was conducted through a systematic search using “driver” and “drowsiness detection” as search keywords in indexing databases including Scopus, PubMed, and Web of Sciences. The search encompassed the latest related research conducted in this field from 2010 to September 2020. The reference lists were also reviewed to find further studies.
Results: In general, researchers evaluate driver’s drowsiness using three methods including vehicle-based measurement, behavioural measurement, and physiological measurement. The details and how these measurements are made make a big difference to the existing systems. In this study, which is a narrative review, the three mentioned measurements were examined using sensors and also the advantages and limitations of each were discussed. Real and simulated driving conditions were also compared. In addition, different ways to detect drowsiness in the laboratory were examined. Finally, after an analytical comparison of the methods of diagnosing drowsiness, a diagram was presented based on which an efficient and combined model was developed.
Conclusion: Taking into account the limitations of each of the methods, we need a combination of behavioural, performance, and other measures to have an efficient drowsiness diagnosing model. Such model must be tested using simulations and in real world situations.

Evaluation of Allowable Weight Limits in Iranian Women Based on Objective and Subjective Criteria: a Laboratory Study

Maryam Mojaddam

Introduction: Occupational back pain is one of the musculoskeletal disorders (MSDs) caused by manual load-lifting among women involved in manual lifting activities. Limits for lifting loads are used to assess the risk and prevention of occupational back pain. The Washington Industrial Safety and Health Act (WISHA) checklist is used as a permissible load assessment limit in Iran. The present study aimed to evaluate the reliability of using the WISHA checklist to determine the allowable limits of manual load-lifting among women based on biomechanical and psychophysical methods.
Material and Methods: In this study, ten women workers aged 20-30 years with a history of manual load-lifting were asked to perform 21 load-lifting tasks designed according to the permitted limits of Iran. A wireless electronic clinometer was used to determine the flexion angles of the trunk while lifting the load. Anthropometric information, load weight, trunk angle, and posture were entered into 3DSSPP software to obtain biomechanical forces for each task and compared them with the recommended National Institute for Occupational Safety and Health (NIOSH) limits. After performing each task, the rate of perceived exertion of each person for each task was collected by using the Borg scale.
Results: The flexion angle for 47.61% of the lifting tasks were more than 20 degrees. The estimated average compressive force for the six tasks exceeded NIOSH’s recommended limits. The average Borg scale was determined hard for 33.33% of lifting tasks and hard to very hard for 9.52% of tasks.
Conclusion: It was found that the manual load-lifting standard for some tasks might not be sufficient to control and prevent low back pain caused by manual lifting in women, and some non-compliance was found with the allowable lifting limits. Manual load-lifting with anthropometric and biomechanical features may increase the biomechanical force on the women’s low back. Therefore, it seems that the allowable lifting limits of Iran for women based on the WISHA checklist should be reviewed and redesigned based on anthropometric and biomechanical characteristics.