Journal of Health and Safety at Work

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Introduction: Choosing maintenance strategy is one of the most complex and essential processes that can affect the safety and cost of equipment. The main aim of this study was to determine a risk-based maintenance policy for improvement of the safety and maintenance indices.

Material and Method: According to literature reviews and constraints associated with the studied industry, a number of safety and maintenance indices were selected and their values were measured. Next, in order to promote the selected indices, the best policy was implemented on nine critical machines of the company based on criteria such as cost, risk and availability in the framework of the fuzzy network analysis process. Finally, after six months period, the indices were re-measured. The Wilcoxon test was used to assess the changes in the indices.

Result: In the implementation of the model, condition based maintenance was more effective than other strategies. Following the intervention, the improvement of safety and maintenance indices was statistically significant. The statistical analyses demonstrated that indices like reliability, availability, mean time between failures, and the number of dangerous failures all were improved significantly (P<0.05).

Conclusion: The results showed that the simultaneous use of three criteria, i.e. cost, risk and availability in maintenance planning could reduce equipment-related accidents. Finally, the recommended model can improve the efficiency and competitiveness of organizations by increasing availability and reducing equipment costs

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Introduction: Air pollution is now recognized as an important environmental and health concern. Biological control processes, due to their durable, cost-effective and eco-friendly, have become a good alternative to physic-chemical methods. Biotechnology is based on the activity of microorganisms.
The aim of this study was to compare the capability of Pseudomonas Putida PTCC 1694 (bacteria) and Polarotus Stratus IRAN 1781C (mushroom) in the removal of toluene from the air stream and its biodegradation under same operating conditions.
Material and Methods: To this purpose, a bio filter containing two parallel columns was designed and constructed on a laboratory scale and the experiments were carried out based on measuring the removal efficiency (RE), elimination capacity (EC) and pressure drop in these two columns. Thus, the bacteria were inoculated in one of the columns and in the other the fungus was inoculated.
Results: The bacterial testing lasted for 20 days and the fungal testing lasted for 16 days. The contaminant loading rates (LR) for bacterial and fungal bio filters were 11.65±2.26 and 11.94±2.56 g/m3.h, respectively. The results showed that the fungal bio filter was more capable of eliminating of toluene vapor than bacterial bio filter (9.65±3.53 vs 9.18±2.6 g/m3.h). However, the pressure drop in the bacterial bio filter was lower than the fungal bio filter (1±0.28 vs 1.1±0.32 cm water).
Conclusion: According to the results, fungal bio filtration appeared to be more successful than bacterial bio filtration in the removal of toluene.

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Introduction: Styrene (C₆H₅CH=CH₂) is known as one of the volatile organic substances produced or used in petrochemical industries. Exposure to this chemical compound can thus lead to respiratory diseases. Therefore, this study aimed to evaluate occupational exposure to styrene vapor and to determine the risks of its health consequences in petrochemical industry workers through a quantitative method.
Material and Methods: In this descriptive cross-sectional study, a total number of 150 samples from 50 employees were studied using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. The samples were then analyzed by the Varian CP-3800 chromatograph. Upon determining exposure to styrene vapor, the risk assessment of the health consequences of styrene in the workers in the given industry was evaluated via the relationships established by the United States Environmental Protection Agency (US/EPA).
Results: According to the results, the polybutadiene latex unit (PBL) was observed with the highest average exposure (0.44 mg.(kg-day)-1). Therefore, the top predictors of carcinogenic and non-carcinogenic risks were valued 0.44 and 0.71, respectively, for the PBL unit. Given the lowest average exposure (0.0012 mg.(kg-day)-1) in the drying unit, the prediction revealed the most moderate carcinogenic (0.1 ×10-5) and non-carcinogenic risks (2×10-3) for the same employees.
Conclusion: Overall, the health risk was higher than the permissible limit in the petrochemical industry studied, especially in the PBL unit. Therefore, it is recommended to make use of artificial ventilation, notably the local type, in addition to the natural ones.

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Introduction: The skin, can be exposed to harmful factors like ultraviolet radiation (UV). Exposure to this physical hazardous agent could be contributed to pigmentation, erythemas, early aging, skin cancer, and DNA damage. The aim of this study, therefore, was to fabricate the polyacrylonitrile (PAN) nanofibers with the UV protection property by the use of various concentrations of titanium dioxide (TiO2) nanoparticles.
Material and Methods: The PAN nanofibers (10%wt) containing 0, 1, 5, 10 and 15% wt of TiO2 nanoparticles were produced using electrospinning method. The morphological propertis of nanofibers were studied by scanning electron microscopy (SEM) and the functional groups were investigated by Fourier transform infrared spectrophotometer (FTIR). The UV protection property of nanofibers was studied by measuring UV transmittance as well as calculating UV protection factor (UPF).
Results: The results showed that the diameter and morphological characteristics of nanofibers are different at various concentrations of TiO2 and increasing the concentration of TiO2 has resulted to an increase in nanofibers diameter. The analysis of FTIR results showed that TiO2 nanoparticles have been successfully loaded on nanofibers for UV protection purposes. The findings clarified that nanofibers loaded with TiO2 could increase the UV protection property up to 15%.
Conclusion: Totally, our findings show the successful fabrication of UV-protective nano webs using TiO2 nanoparticles. the new combination used in nano matcould protect employees from UV radiation.

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Introduction: One of the most important factors affecting quality of work-life (QWL) is the workload in the form of mental and physical. The increased workload may reduce the level of performance of workers. Therefore, the present study aimed to evaluate the relation of the mental and physicalworkload with the QWLof workers in the foundry industry.
Material and Methods: This cross-sectional study was conducted on 218 male workers in a foundry industry and the work units with high work stress were selected. The NASA-TLX, physical load and the Walton questionnaires were used to collect and evaluate the workload and the QWL.The SPSS software was used for data analysis.
Results: It was clarified that there was a significant inverse relationship between QWL with physical load (P = 0.001) and mental workload (P = 0.01). The comparison of mean QWL between different groups of demographic variables showed that the only significant relationship was between different age groups and QWL (P = 0.003). Finally, it was found that the variables of physical load, mental workload and age had a significant simultaneous effect on the mean score of QWL (P<0.05).
Conclusion: The findings showed that there was a significant relationship between QWL and mental and physical workloads.

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Introduction: The study of noise has always been of interest to occupational health professionals as a harmful physical factor in the workplace. However, the psychological and psychoacoustic aspects of noise in the workplace have been less studied. This study has dealt with different colors of noise and their applications in psychoacoustics.
Material and Methods: This review study was conducted by searching the databases of Google Scholar, ProQuest, Science Direct, PubMed, and Scopus to extract the articles related to the research subject within a 50-year interval from 1970 to 2020.
Results: Based on the results of the present study, colored noises and white noise seem to have the potential to be used as acoustic stimuli to improve the sleep of employees, especially shift workers, to improve memory and attention, especially in jobs that require high care and attention. Colored noise and white noise have potential applications to improve cognitive function in different occupations to reduce the activity of the sympathetic nervous system and anxiety and stress, especially in jobs with high job stress. Also, these noises are helpful for people’s privacy, especially in the open workplace, for noise masking and noise control purposes, as well as for medicine and treatment of disorders such as tinnitus, ADHD, and hyperacusis.
Conclusion: Paying attention to the colors of noise and their psychoacoustic impacts shows us that the noise impacts are not limited to their undesirable and damaging effects. Instead, their positive and applied aspects should also note. Familiarity with such aspects and their introduction can identify the existing information gaps in this field and pave the way to fill them.

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Introduction: Oxygen-generating central plays a vital role in the continuous performance of hospitals. Any leakage or failure in this section can not only endanger the health and safety of patients but also cause fire and explosion. Probabilistic risk assessment is a useful tool for identifying the main root causes of leakage in oxygen-generating central. This study aimed at risk assessment of an oxygen-generating central in a hospital in Hamadan using fuzzy sets theory and Bayesian networks.
Material and Methods: First, all root causes supposed to contribute to oxygen leakage from any part of the oxygen-generating central were identified, and based on them a fault tree analysis (FTA) was constructed. Then, the FTA was mapped in a BN. The failure probability of root causes was calculated using fuzzy sets theory and experts’ opinions. Belief updating based on BN was utilized for subsequent analyses.
Results: According to this study, ignorance of labels on the oxygen generation and distribution system is the most important root cause leading to oxygen leakage. Moreover, removing masks from patient’s faces is the main cause of oxygen leakage in patient rooms. Once leakage occurred, the presence of an ignition source can lead to fire or explosion.
Conclusion: oxygen leakage can create considerable risks in hospitals. All staff should be provided with sufficient training regarding hazards of oxygen-generating and distributing systems and oxygen leakage. Particular attention should be paid to such leakages and their adverse consequence in emergency planning and hospital crisis management.

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Introduction: Affinity for Technology Interaction (ATI) refers to the users’ tendency to actively interact with a digital system. ATI is a personal characteristic affecting many aspects of human-technology interaction. The present study aimed to assess the psychometric properties of the Persian version of the ATI scale.
Material and Methods: The Persian version of the scale was developed in accordance with the forward-backward translation approach. The construct validity of the scale was assessed using exploratory and confirmatory factor analyses. The correlation of the scale with the Big-five personality traits, need for cognition (NFC), age, gender, and field of study was also investigated.
Results: In contrast to the original scale, the Persian ATI had two components, confirmed by the exploratory and confirmatory factor analyses. The first component contained eight items and the second contained one item, item 3. So, this item was removed from the scale. The 8-item scale demonstrated excellent reliability (coefficient=0.90). The Persian ATI was not significantly correlated with extraversion, agreeableness, conscientiousness, and neuroticism (p>0.05). In contrast, it was significantly correlated with openness to experience (0.175, p<0.01) and NFC (0.36, p<0.01). The Persian ATI score for men was higher than for women. Various age groups were not significantly different in terms of the Persian ATI score.
Conclusion: In contrast to the original version, the Persian version of ATI is composed of eight items. Other characteristics, including unidimensionality and correlation with other personality traits, are similar to the original version.

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Introduction: Given the high prevalence of low back pain in manual handling activities, its known relationship with spinal loads, and the role of muscular fatigue and the body’s adaptive mechanisms to counteract fatigue, this study investigated the effect of repetitive lifting tasks on trunk muscular fatigue and the kinematics of the spine and load-in-hand.
Material and Methods: Eighteen male volunteers lifted a box from the floor to their waist height at a pace of ten lifts per minute until they could no longer continue the task and reported the highest level of exhaustion. Kinematic data and muscle electromyographic activity were simultaneously recorded using a motion capture system and an electromyography device. In this study, average trunk flexion angle and trunk angular velocity were calculated as trunk kinematic variables, while average box vertical travel distance, average box horizontal displacement from L5-S1, and average box vertical displacement velocity were considered as box kinematic variables. The median frequency of electromyographic signals from selected muscles was quantified as a muscle fatigue indicator. Since subjects performed different lifting cycles, the total number of cycles was divided into five distinct blocks for data analysis.
Results: The results showed significant effects of lifting trial blocks on trunk angle (p=0.004) and vertical box displacement (p<0.001). Median frequency was significantly affected by lifting blocks for right (p=0.016) and left erector spinae (p=0.014), right (p=0.021) and left multifidus (p<0.001), right latissimus dorsi (p=0.001), and left rectus abdominis (p=0.039).
Conclusion: Overall, the results highlight variations in most kinematic parameters and a reduction in the frequency content of EMG signal spectra. These changes serve as indices of the central nervous system’s control over lifting behavior under dynamic conditions. A better understanding of these central nervous system adaptations could have practical applications in interventions such as workstation design, exoskeleton development, and worker training to manage musculoskeletal disorders.

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Introduction: In many occupations, users must sit for prolonged periods during their job activities. Prolonged sitting is associated with fatigue, leading to postural changes that can increase spinal loads. Despite the importance of this topic in terms of the extent of prolonged sitting and its subsequent adverse consequences, little attention has been given to this occupational activity. Hence, this study investigates changes in neck, trunk, and muscle activities and fatigue levels in prolonged sitting computer tasks.
Material and Methods: Twenty healthy subjects (gender-balanced) from the student community with at least five years of experience in computer work aged between 20-30 years were asked to randomly perform three types of computer tasks for 90 minutes (each task for 30 minutes). Electromyographic (EMG) activities of right and left cervical (ESCR and ESCL), thoracic (ESTR and ESTL), and lumbar (ESLR and ESLL) erector spine and upper trapezius (UTR and UTL) muscles were continuously recorded. Root mean square (RMS) and median frequency were extracted as EMG metrics. Subjects also rated their perceived discomfort using a Visual Analogue Scale (VAS). The effect of time, gender, and their interaction on muscle EMG activities, fatigue, and discomfort were explored.
Results: Time had a statistically significant effect on UTR, ESCR, and ESTR muscle activities. UTL and ESCR muscle activities significantly differed between male and female subjects. Further, the findings confirmed the interactive effect of time and gender on ESTR muscle activity. UTR, ESCR, ESCL, ESTL, and ESLL muscles’ fatigue index changed statistically over time.
Conclusion: The findings confirmed neck and trunk muscles’ fatigue by increasing muscular activity and reducing frequency contents over time, per the subjective rating of discomfort.

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Introduction: Prolonged sitting postures are among the risk factors for musculoskeletal disorders in occupational settings, leading to increased musculoskeletal discomfort in various body regions. This discomfort can negatively impact individuals’ health and impose high costs on society in terms of work absences, early disabilities, and reduced productivity. The purpose of this study is to investigate the effect of stretching exercises on the level of discomfort, muscle activity, and muscle fatigue in the neck and trunk region during prolonged sitting tasks.
Material and Methods: This experimental study was conducted among 20 healthy male and female participants under two test conditions: control and intervention. In the control condition, participants performed cognitive tasks (watching videos, typing, text editing, and nback cognitive test) without any intervention. In the intervention condition, participants performed stretching exercises before each task. The Visual Analogue Scale was used to assess perceived discomfort. Also, muscle fatigue was evaluated using an electromyography (EMG) device and RMS and MPF measures.
Results: Discomfort in hands and arms (p-value=0.04) and lower back (p-value=0.03) during video-watching was higher in the control condition than in the intervention. Regarding muscle activity, the activity of the right cervical erector spinae during the video-watching task was lower in the control condition than in the intervention. In the n-back cognitive test and text editing, the right lumbar erector spinae muscle activity was significantly higher in the control condition than in the stretching exercises intervention. Regarding the left cervical erector spinae, a significant difference was observed between fatigue in control and intervention conditions during the video-watching task. Also, right thoracic erector spinae fatigue in text editing was higher in the control condition than in the exercise intervention; however, for the n-back test, the level of fatigue was lower in the control condition compared to the intervention.
Conclusion: The perceived discomfort in seated computer tasks is generally lower in the exercise intervention compared to the control condition. The stretching exercises used in this study improved muscle activity and reduced fatigue in some of the trunk muscles, although the effects of the exercises depend on the type of task. Overall, muscle fatigue in two cognitive tasks, text editing and n-back, was more affected by stretching exercises than other tasks.

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Introduction: Toluene is significant pollutants in the air. Long-term exposure to toluene can lead to adverse effects.  Biofiltration is one of the air pollutant control methods. In this study, Pseudomonas putida was selected as a microorganism capable of hydrocarbon degradation and its ability to biodegrade toluene in a suspension growth reactor was also investigated.
Material and Methods: Experiments were conducted in two days and in five hours. Each method consisted of three sample reactors (A, B, C) and one control reactor (D). In the first method, the amount of bacteria in the sample reactors is 0.5, 1 and 2 McFarland and the amount of toluene injection into the reactors is the same (0.5 microliters) and in the second method, the amount of toluene injection into the sample reactors is 0.5, 1 and 1.5 microliter and 1.5 microliter in the control reactor and the amount of bacteria in them was the same (1 McFarland).Toluene gas samples and carbon dioxide were periodically analyzed.
Results: In the first method of toluene decomposition, there was a significant difference between the three reactors (p-value = 0.002). The results of the second method were also significantly different between the three reactors (p-value<0.001). The decomposition of toluene in two methods also had a significant difference (p-value = 0.232). The amount of CO2 production was significantly different in the second method (p-value=0.003) and the first method (p-value<0.001), but no significant difference was observed in the comparison of the two methods (p-value=0.15).
Conclusion: Increasing bacterial in suspension growth reactor resulted in increased toluene biodegradation in shorter time while increasing toluene in suspension growth reactor may not have an additive effect on the biodegradation process.

 

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Introduction: The design of traffic signs should consider human cognitive abilities to enhance drivers’ understanding of the signs. Cognitive features, as one of the crucial principles of ergonomics, are among the influential factors in the design of signs. The present study aimed to evaluate the effect of graphic elements of eight new sign designs based on cognitive features on conveying the message “prohibition of using mobile phones.”
Material and Methods: This study was conducted in six driving schools in Tehran in 2013. One hundred seventy-four participants, with an average age of 23.5 and a standard deviation of six years, participated in this study. Participants were then presented with the designed signs through a colored questionnaire. They were instructed to evaluate the signs’ cognitive features including simplicity, concreteness, meaningfulness, and semantic closeness—using a Likert scale ranging from 0 to 100. 
Results: The results revealed that the average score of the cognitive features of the designed signs is higher than other traffic, industrial and pharmaceutical signs. In this study, “semantic closeness” was the best cognitive feature for predicting the message of the signs. The sign with the “hands-free” element had the best performance in transferring the message.
Conclusion: This research aimed to identify the most effective of eight proposed signs for banning mobile phone use while driving. Participants rated the sign featuring a button phone with a hands-free symbol as the top choice. Although most of the mobile phones in the market are of the touch screen type and the use of button phones has decreased a lot, the symbol of these phones as the dominant symbol still effectively conveys messages.
 

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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: 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: Sugarcane is an important and strategic product in many countries, including Iran. While the introduction of mechanization, e.g., sugarcane harvesting machines, has significantly enhanced the production process, operators of these machines still face many ergonomic and safety challenges. 
Material and Methods: The present study investigated the ergonomic status of sugarcane harvester operators by examining some of their physiological and physical evaluations. Physiological evaluations included heart rate, oral temperature, and energy consumption of the operators, perceptual strain index, and physiological strain index. Physical evaluation included estimating the amount of pain and discomfort in body segments. The correlation between pain and discomfort of body parts with some demographic and physiological indices of users was investigated using IBM SPSS 24 software.
Results: Sugarcane harvester operators’ heart rate, energy consumption, and physiological strain index were 79.05 beats/min, 18.81 kJ/min, and 0.83, respectively. The average of three indices of thermal sensation, perceived exertion of activity, and perceptual strain index were estimated as 4.40, 9.21, and 8.86, respectively.
Conclusion: Pain and discomfort in the neck and back segments, like many agricultural activities, had the highest rate among the body parts. Also, shorter and thinner operators reported higher pain and discomfort in some segments of the body. 
 

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Introduction: Operating room personnel are involved with occupational physical activities such as repetitive bending, holding surgical tools and standing for long hours that can lead to musculoskeletal disorders (MSDs). Low back pain (LBP) is the most prevalent and costly problem among these disorders. The aim of this study was to determine the relationship between occupational physical activity, LBP and disability among operating room personnel.
Material and Methods: A total of 60 operating room personnel voluntarily participated in the study, all of which had at least two years of working experience. At the end of a working week, the degree of disability and pain were assessed by Graded Chronic Pain (GCP) questionnaire. The International Physical Activity Questionnaire (IPAQ) was used to evaluate the level of physical activity. Simple linear regression was conducted to investigate the relationship between physical activity, LBP and disability. 
Results: The survey using the GCP questionnaire revealed that 58.3% of participants reported experiencing occupational back pain, while 41.7% reported no back pain.  Among those with back pain, the average pain intensity was rated 43.11 (18.22) on the scale.  Pain remained stable for an average of 2.3 days (standard deviation = 0.95).  The average level of disability associated with back pain was 32.09 (27.44). Statistical analysis using simple linear regression showed a significant relationship between back pain and several factors: vigorous physical activity (p-value = 0.02), prolonged sitting time (p-value = 0.01), and chronic pain (p-value < 0.001).
Conclusion: Occupational physical activity characterized by low intensity, but high repetition and standing for a long time in fixed postures were the most significant contributors to lumbar back pain among operating room personnel. Chronic pain in this population was reported as grade 2, indicating severe pain with minimal disability; if left unaddressed, this could lead to movement restrictions.