Journal of Health and Safety at Work

Challenges on Hospital Fire Safety during COVID-19 Crisis

Farahnaz Khajehnasiri

Study of the effect of shape on acoustic performance of micro perforated absorbent at low frequencies

Mohammad Reza Monazzam

Introduction: Micro-perforated absorbents are one of the structures that are widely used nowadays. The sound absorption mechanism is performed by viscous energy losses in the cavities on the plate. In this study, the acoustic properties of non-flat perforated panels in oblique angle was investigated in numerical method.
Material and Methods: This paper examined the effect of the surface shape on the micro perforated absorber performance at low frequencies (less than 500 Hz). The three-dimensional finite element method was used to predict the absorption coefficient of this group of adsorbents. Also, the results obtained from the shaped absorbents were compared with the flat micro perforated ones. After validating the numerical results, six different designs were defined as the surface shape of the micro perforated plates in the COMSOL Multiphasic, Ver. 5.3a software
Results: The results reflected the fact that the factor of the surface shape can be used as a contributing factor in lower frequencies. In general, the dented or concave shapes provide better outcomes than other flat designs and shapes and the convex or outward shapes bring the weakest results.
Conclusion: To explain this function, shaping creates a phase difference and angling the sound wave and creates a variable depth behind the micro-perforated plate. It also influences the reflection process which affect the absorption coefficient.

The effect of using cervical exoskeleton on the neck and shoulder muscles electrical activity during overhead work

Adel Mazloumi

Introduction: The use of exoskeletons as a new ergonomics intervention to reduce musculoskeletal disorders risk factors and increase human performance has emerged in the fourth-generation industrial revolution. The aim of this study was to assess the cervical exoskeleton effect on the neck and shoulder muscles electrical activity.
Material and Methods: In this experimental study, 14 male participants were asked to perform the simulated overhead work with and without using the cervical exoskeleton at two neck postural angles randomly. During the task, electromyography of the target muscles in the neck and shoulders was recorded. In addition, at the end of each task, participants completed a perceived discomfort questionnaire. Electromyographic signals were processed with Matlab 2017b software and the level of the electrical activity of the target muscles was normalized to the maximum muscle activity. Data analysis was performed using Random intercept mix model in STATA 14 software.
Results: Mean perceived discomfort in the neck and shoulders regions significantly reduced by the exoskeleton device, but there was no statistically significant difference in other areas. Also, the mean activity level of sternocleidomastoid and splenius capitis muscles on the right and left was significantly decreased during the use of the cervical exoskeleton. However, this difference showed a significant increase in trapezius muscles.
Conclusion: The use of the neck exoskeleton was associated with a reduction of muscle electrical activity and the perceived discomfort in the neck area. These results may be related to transferring neck and head weight by the exoskeleton retaining jack during the neck extension to other areas of the body. The exoskeleton design did not provide support for the shoulder and arm area, which explains the reason for the non-significant results in the shoulder area. Using the exoskeleton with the additional support in shoulder area could be considered as an ergonomic intervention in such overhead works.

Comparative Survey of Virgin and Immobilized Activated Carbon With Pseudomonas Putida PTCC In Toluene Removal From Airflow

Farideh Golbabaei

Introduction: Volatile organic compounds are the most common pollutants in the air, and among them, toluene is the most common form, which is toxic resulting in liver and kidneys damages. Regarding the fact that this compound is widely used in various chemical industries, implementing an efficient method for controlling its concentration is of great importance. The comparative survey of the capability of virgin activated carbon with the one immobilized by pseudomonas putida PTCC, and also the performance of the biofiltration system involving pseudomonas putida bacteria immobilized on activated carbon for the adsorption and degradation of toluene from the air as well as regenerating the activated carbon were aimed in the present study.
Material and Methods: The microbial growth process was initiated by incubation of pre-culture in a rotary shaker, at 150rpm overnight. After 4 days, the strain pseudomonas putida, PTCC No: 1694 was immobilized on a certain amount of activated carbon. Subsequently, an airstream containing toluene was introduced into the biofilter, and the inlet and outlet concentrations of toluene were measured.
Results: The obtained results illustrated that the increase in the volume of the media and decrease in the gas flow rate significantly enhances efficiency. The great performance of the biofilter was confirmed by the high efficiency of the immobilized activated carbon which exhibited 89% yield during 14 hours. On the second cycle, the biofiltration system was able to adsorb toluene at an efficiency of 81%, while the virgin activated carbon exhibited far less efficiency with the value of 28%.
Conclusion: The provided results demonstrated the feasibility and reusability of the biofilter system for toluene removal. The proposed technique also extends the activated carbon’s capacity, which could be a potential solution to re-use the activated carbon in industrial applications.

Investigating the protective effects of aqueous extract of the wormwood plant (Artemisia absinthium) on alumina nanoparticle-induced pulmonary toxicity in male Wistar rats

Seyed Jamaleddin Shahtaheri

Introduction: Although aluminum oxide nanoparticles (Al2O3-NPs) are the most widely used nanomaterials, limited studies have been reported on their toxicology. Therefore, the present study aimed to investigate the potential toxicity of aluminum oxide (alumina) nanoparticles and the protective role of aqueous extract of wormwood plant on nanomaterial-induced disorders in the lung of rats.
Material and Methods: Here, 36 male Wistar rats were randomly divided into six groups. Next, the rats were first exposed to 200 mg/kg of the aqueous extract of wormwood plant (by gavage) for 15 days and then received a dose of 30 mg/kg of aluminum oxide nanoparticles as an intraperitoneal injection for 14 days. Furthermore, various features of clinical signs, body weight, biochemical parameters, gene expression changes, lung weight ratio, histopathological observations, and metal content in lung tissue were evaluated during the experiment. Eventually, the ANOVA (Analysis of Variance) and Tukey’s range test were employed to analyze and compare the mean of the data.
Results: The results revealed that aluminum oxide nanoparticles at a concentration of 30 mg/kg body weight led to changes in antioxidant enzyme activities, e.g., T-SOD, CAT, GPx, and TAC, lipid peroxidation, and iNOS for exposed rats. Also, the above biochemical disorders were associated with altered expression of oxidative stress-related genes (HO-1, MT-1) and histological changes in the lung tissue. On the other hand, simultaneous intake of aqueous extract of wormwood plant and aluminum oxide nanoparticles in rats significantly improved the studied parameters (p <0.05).
Conclusion: Our findings showed that the γ-Al2O3 NPs were more toxic than α-Al2O3 NPs, which can be attributed to changes related to their size and shape characteristics. Also, it was observed that the wormwood plant could play a protective role against aluminum oxide nanoparticles-induced pulmonary toxicity in rats.

Transmitted vibrations to the wrist and arm of a chainsaw operator: The effect of wood cutting process

Masoud Feyzi

Introduction: Due to the non-developed mechanization situation, chainsaw is a widely used tool in Iranian forests. This tool can trigger unwelcome disorders (e.g., white finger syndrome) due to the transmitted vibrations from its handle to the body members. Characterizing these vibrations can result in minimizing the intensity of these disorders. This study aims to investigate the effect of different hardwood species (Beech, Hornbeam, and Alder) on the vibrations transmitted to the wrist and arm.
Material and Methods: Experiments are conducted during four operations including Beech-, Hornbeam-, and Alder-cross-cutting and without cutting as the control sample. Vibration accelerations in three directions of a local Cartesian coordinate system are measured at three points including chainsaw handle, operator's arm and wrist. Using the time and frequency spectra of vibration accelerations, root mean square (RMS), total vibration acceleration, total vibration transmissibility, and frequency-weighted vibration acceleration are calculated based on ISO 5349 (2001) and ISO 10819 (2013) standards. The calculated parameters were statistically analyzed in SAS.
Results: The results showed that variations in wood species could significantly affect the RMS at all three points. The RMS magnitude decreases from handle towards the arm. Interestingly, a significant variation in vibration transmissibility is observed in different frequencies. This study confirms that body organs can damp the high-frequency vibrations better than the low frequency ones.
Conclusion: Although the RMS for cutting operations is less than the control sample, frequency-weighted vibration acceleration and consequently the risk of white finger syndrome is higher in cutting regimes. Furthermore, some vibration accelerations (below 40 Hz for wrist and below 25 Hz for arm) are amplified during transmission despite significant damping in total vibrations.

Investigation of the effects of using ribs on cyclone’s vortex finder on its performance

Farshid Ghorbani-Shahna

Introduction: Generally, geometrical parameters of the cyclone have a profound effect on determining its performance. The air outlet (Vortex Finder) as one of the cyclone’s components has a significant impact on the cyclone’s internal flow pattern, pressure drop and even dust removal efficiency.
Material and Methods: Two different air outlets were designed in order to be easily installed and removed. The ribs (both in the opposite and the same swirl direction with the air flow) were inserted at the inner wall of the vortex finder. The step length of the blades was calculated to be 1.5. The dust feeder was injected the silica particles with a concentration about of 2.1 gr/m³ into the inlet air. The results of dust removal efficiency of the cyclone were calculated and compared for three groups of total dust, PM₁₀ and PM_2.5 in different experimental conditions.
Results: Installation of spiral blades in same swirl direction as the air flow inside the cyclone increased 7.75, 7.73 and 6.75 percent in total efficiency, PM₁₀ and PM_2.5, respectively. The dust removal efficiencies for total dust, PM₁₀ and PM_2.5 increased by 2.6%, 2.33% and 1.5%, respectively, when the swirl direction of ribs and air flow was the opposite. The effect of helical blades on pressure drop for the first experimental setup (same direction) decreased by (- 2.5%) and in the second one (opposite direction) increased by (+ 2.03%). The best quality factor was also calculated for the cyclone with the blade aligned with the air flow direction.
Conclusion: Use of ribs in the inner wall of the cyclone vortex finder, especially when the rotation direction of the ribs and airflow are the same, leads to a decrease in pressure drop and increase in dust collection efficiency which finally leads to improvement of cyclone performance.

Development of a human error risk assessment model in high priority emergency situation using TOPSIS, FUZZY-AHP and CREAM method

Iraj Mohammadfam

Introduction: Emergencies are unforeseen and unpredictable situations. In these situations, people’s performance is affected by various factors that cause stress. People’s performance in such situations can also affect human error probability. The purpose of this study was to evaluate human error in emergency situations based on the fuzzy CREAM and Fuzzy Analytical Hierarchy Process (FAHP).
Material and Methods: This descriptive-analytical study was performed in a petrochemical industry in Markazi province in 2019. The FAHP was used to prioritize emergency situations. To evaluate human error in these conditions, the weights of Common Performance Conditions (CPC) was determined using Analytical Hierarchy Process (AHP) method. Human error probability was calculated using a fuzzy CREAM method in the most important emergency situations.
Results: The results of the FAHP showed that “Hydrogen leak from the cylinder joints in the olefin unit” was the most important emergency. The highest relative weight was related to crew collaboration quality (0.06) in the emergency situation.
Conclusion: This method can also be used to identify the important factors in human error occurrence and high weighted CPCs and plan to control them.

The relationship between demographic information and bag weight with neck disability index, angles and head and neck postures among college students

Sakineh Varmazyar

Introduction: Using backpacks has arisen complaints regarding musculoskeletal pains among students. The aim of this study is to investigate the relationship between demographic information and bag weight with Neck Disability Index (NDI), angles and head and neck postures among students.
Material and Methods: This descriptive-analytical and cross-sectional study was conducted among 80 students who were selected randomly. Demographic information and NDI questionnaires were used for data collection. The head and neck tilt angles and the amount of change in the forward head posture were determined using the photogrammetry method and Kinovea software.
Results: A negative and significant correlation was observed between head tilt angle with age (r = - 0.27) and neck tilt angle with body mass index (r = - 0.37). Also, a positive and significant correlation was observed between the amount of change in the forward head posture and body weight (r = 0.24). The head tilt angle was significantly different in male and female students at different educational levels. NDI (r = 0.23) and neck tilt angle (r = 0.26) also increased significantly with increasing bag weight.
Conclusion: Reviewing the standard weight of bag and changing the lifestyle can play an important role in improving the head and neck angles and postures.

Acoustic properties of 3D printed bio-degradable micro-perforated panels made of Corkwood Fiber-Reinforced composites

Seyyed Bagher Mortazavi

Introduction: Micro perforated panel (MPP) absorbents promise the next generation of sound absorbers as they have significant advantages over other porous adsorbents. In this study, we will investigate the acoustic performance of MPP absorbents made of biodegradable polylactic acid composite reinforced with natural corkwood fibers (PLA/Corkwood) by 3D printing technology.
Material and Methods: First, the effective dimensional characteristics of the parameters were determined, then, all of the samples were fabricated by the Zortrax M200 3D-Printer using the FDM method. The normal incidence sound absorption coefficient of the samples was measured using an acoustic impedance tube according to ISO 10534-2 in the frequency range of 64 to 1600 Hz. Then the effect of four geometric parameters, including hole diameter, panel thickness, perforation ratio, and air gap depth, on the absorption coefficient was studied.
Results: The findings show that the SL-MPP 12 absorbent has the highest average sound absorption coefficient (SACA) with a value of 0.28, so that at a frequency of 804 Hz it has the highest sound absorption equal to 0.91. The parametric study found that as the hole diameter increased, the values of peak adsorption and average absorption coefficient were decreased. Increasing the MPP thickness causes the absorption peak to move towards the lower frequency range. Decreasing the perforation ratio increases the peak absorption values and the average sound absorption, and the frequency with the highest absorption also moves towards the higher frequency range. The resonant frequency also depends on the depth of the air gap behind the screen. Changes in air gap depth from 30 mm to 70 mm reduced the resonant frequency by more than 35%.
Conclusion: Using 3D printing technology, sustainable MPP can be fabricated with more quality and in less time than traditional methods such as mixing and heat pressing.

The role of individual and psychological differences in the occurrence of unsafe behaviors: a cross-sectional study between the employees of a turbine manufacturing company

Mostafa Pouyakian

Introduction: Human beings are inherently different and this fact can affect his/her behavior in work environments. The aim of this study was to examine the individual differences of employees (personality traits, biological and demographic factors) as a predictor of unsafe behaviors in a turbine manufacturing company.
Material and Methods: In this cross-sectional study, safety behavior sampling technique, NEO-FFI questionnaire, demographic information questionnaire, BMI and cell type method were used to determine unsafe behaviors, personality traits, demographic variables, body mass index and blood group system, respectively. The statistical sample of the study was 260 employees of a turbine manufacturing industry. The SPSS software version 20 was used to analyze the data.
Results: The results showed that 44.5% of employees’ behaviors were unsafe. There was a significant relationship between the occurrence of unsafe behaviors with smoking, BMI, blood type and neuroticism and agreeableness dimensions measured by NEO-FFI (p < 0.05). BMI was the most important predictorof unsafe behaviors in the present study.
Conclusion: Due to the role of individual differences in people’s tendency to unsafe behaviors, the results of this study can be considered in job design, screening of personnel according to their individual differences, and perform better interventions to prevent accidents at work.

Investigating relationship between sleep disorders and work ability among workers in construction workshops

Ali Karimi

Introduction: Sleep is one of the important physiologic needs in daily life cycle, and a part of quality of life. Sleep disorders are considered as one of the most common health problems in work communities that can affect physical, mental performance and ability to work. Therefore, this study aimed at investigating the relationship between sleep disorders and work ability in construction workers.
Material and Methods: This study is descriptive-analytical and cross-sectional. Samples of 220 people were selected by random sampling method from construction workers and personnel. Data collection tools in this study included sleep quality questionnaire, insomnia severity questionnaire and work ability questionnaire. Data were analyzed using SPSS software (version 19) and, considering the objectives, descriptive statistics and analytical tests including paired t-test, Pearson’s correlation, Kruskal-Wallis, multiple linear regression and logistic regression were used.
Results: Average age, body mass index, working hours and work experience were calculated as 34.2 ± 8.5 years old, 55.58 ± 2.78, 10.5 ± 1.25 hours and 12.7 ± 6.5 years, respectively. The mean indices of insomnia severity, Petersburg quality of sleep index and work ability were 6.6 ± 5.35, 4.95 ± 2.43 and 42.5 ± 5.13, respectively. The relationship between the work ability with sleep disorders was statistically significant. Variables of marital status, types of employment and smoking, independent of the variables of insomnia severity and sleep quality, significantly affected the work ability index, so that the R² of these variables were 0.246 and 0.242 of the changes in work ability index, respectively.
Conclusion: Any disturbance in sleep and resting can cause poor sleep quality. As a result, it severely reduces the ability of employees to work. Therefore, it is suggested that, in order to increase the index of work ability and, thus, the efficiency of an organization, special attention be paid to sleep-resting programs of employees.

Analysis of the safety effectiveness of methane gas valve pits: A Case Study in the Steel Industry Based on Hazardous Areas Classification

Ahmad Soltanzadeh

Introduction: Methane is one of the most widely used gases in industries with a high flammability potential. This study aimed to evaluate the efficiency of ventilation systems installed on methane valve pits based on hazardous areas classification.
Material and Methods: This study was implemented in a steel industry in Qom Province in 2019. The tools used in this study were a DELTA OHM pitot tube (DO-2003) to measure wind speed, EPA Protocol for equipment leak emission estimates (U.S. Environmental Protection Agency) and IEC-60079-10 for evaluating the safety of ventilation of methane valve pits.
Results: The methane LELm was about 0.0334 kg/m³, and the volume of the release area was approximately VZ = 0.053 m³. The expected leak emissions were within the Vz < 0.1 m3 range. The ventilation system embedded on methane distribution pipelines was not effective for openings with diameters of more than 0.3 mm and the volume of gas inside the valve pits would quickly exceed high ventilation border which might lead to a dangerous accumulation of gas in the valve pits.
Conclusion: Given that a very small opening or leak in gas transmission valves may lead to the formation of an explosive atmosphere, it is essential to monitor methane before entering the valve pit area and performing any operations on valve pits.

Relationship of abnormal profiles and the prevalence of musculoskeletal disorders among academic staff men and women

Mojtaba Babaei Khorzoghi

Introduction: Work-related musculoskeletal abnormalities are one of the main causes of musculoskeletal injuries, followed by job-disability among employees. The purpose of this study was to investigate the relationship between abnormal profiles and the prevalence of musculoskeletal disorders (MSDs) among academic staff men and women.
Material and Methods: The present study is of a causal nature after occurrence. The statistical population consisted of all employees of Isfahan University of Technology in 2018. A random sample of 64 men and 59 women were recruited as the study sample. A New-York-based assessment questionnaire was used to assess musculoskeletal-abnormalities and a Nordic questionnaire was used to assess the extent of MSDs. For data analysis, descriptive statistics and Spearman test were used in SPSS version24 software.
Results: The highest musculoskeletal abnormality in the upper limb was observed in shoulder area (0.37%) and among the lower limbs the ankle (0.82%) was reported as the highest. In terms of correlation between pain, disability and injuries and MSDs with gender in the last 7 days, there was the highest correlation with shoulder (r=0.377), wrist (r=0.401) in the last 12 months and musculoskeletal abnormalities with shoulder area (r = 0.411). There was a significant difference in the prevalence of pain and disability with injury in the shoulder area (P = 0.001), wrist (P = 0.001), back (P = 0.002), buttocks (P = 0.032) and knees (P = 0.006).
Conclusion: The results indicate a high risk of MSDs and abnormalities in male and female employees. In order to reduce the incidence of abnormalities, it is necessary to perform corrective exercises and improve the ergonomics conditions of the work environment.