Journal of Health and Safety at Work

Introduction: Process industries, often work with hazardous and operational chemical units with high temperature and pressure conditions, such as reactors and storage tanks. Thus, probabilities of incidence such as explosions, and fire are extremely high, The purpose of this study was to present a comprehensive and efficient method for the quantitative risk assessment of fire and explosion in the process units.

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Material and Method: The proposed method in this study is known as the QRA and includes seven steps. After determination of study objectives and perfect identification of study process, first, qualitative methods are used to screen and identify hazard points and the possible scenarios appropriate are identified and prioritized. Then, estimation of frequency rate are done using past records and statistics or Fault Tree Analysis along whit Event Tree. PAHST professional software and probit equations are used in order to consequence modeling and consequence evaluation, respectively. In the last step by combination of consequence and frequency of each scenario, individual and social risk and overall risk of process or under study unit was calculated.

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Result: Applying the proposed method showed that the jet fire, flash fire and explosion are most dangerous consequence of hydrogen generation unit. Results showed that social risk of the both fire and explosion caused by full bore rupture in Desulphrizing reactor (Scenari3), Reformer (scenario 9) and Hydrogen purification absorbers are unacceptable. All of the hydrogen generation unit fall in ARARP zone of fire individual risk (FIR) and FIR up to 160 m of boundary limit unit is unacceptable. This distance is not only beyond of hydrogen generation unit boundary limit, but also beyond of complex boundary limit. Desulphurization Reactor (75%) and Reformer (34%) had the highest role in explosion individual risk in the control room and their risks are unacceptable.

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Conclusion: Since the proposed method is applicable in all phases of process or system design, and estimates the risk of fire and explosion by a quantitative, comprehensive and mathematical-based equations approach. It can be used as an alternative method instead of qualitative and semi quantitative methods.

Introduction: In HSE management systems competency has been considered as an important tool for selecting managers and resource allocation. Lack of proper HSE managers can undermine the performance of the management system. On the other hand competent HSE managers can improve the performance of management system and reduce the time to perform activities. This study was aimed to present a model to select the HSE managers.

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Material and Method: In this study, similar models were examined to select the basic framework. Model dimensions and weights were determined using the focus group technique. The model was used in a large industrial company. The model was approved by the evaluation of the results and correction of the identified defects.

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Result: The approved model included technical, behavior and concept competence. Technical competence for managers in level 1 and 2 and behavior competence for managers in level 3, were the most important dimensions.

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Conclusion: HSE managers in various level should have different competencies which can be evaluated by presented model in the current study, before employment and also it can be used as a basis for monitoring individuals during specific period of time.

Introduction: Following the presentation of Domino model by Heinrich in 1931 this idea was formed that human is the most important cause of accidents. According to Heinrich, unsafe behavior (88%), unsafe condition (10%) and unexpected factors (2%) are involved in accidents causation. Thus, the aim of this study was to investigates workers safety, culture and its influencing factors in detergent and cleaner company.

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Material and Method: In order to determine the level of safety culture in the understudy detergent producing company a questioner developed in 2010 was used. It was included dimensions of management commitment, training and information exchange, protective environment, inhibitory factors and priority to safety. After collecting the questionnaires, data were analyzed using SPSS version 17.

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Result: The mean age of the participants of 37.5 years old and the mean work experience 13.7 years. 52.3 % of workers had not experienced any accident during their working year. Moreover, mean (SD) score of safety culture was 180.51 (±35.216).

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Conclusion: The difference of safety culture score were statistically different among occupational groups and also between workers with and without accidents.

Introduction: Human and environment exposed to harmful factors, as the result of industrial pollutants. Volatile organic compounds (VOCs) play important role in photochemical reactions in troposphere layer of atmosphere and results in production of ozone and photochemical oxidants.

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Material and Method: In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing xylene. In the next step, the bioreactor incubated with microbial consortiums with ratio of 1 to 3. The performance of bioreactor in treatment of xylene vapors in presence of 10% silicone oil, as an organic phase was assessed in concentrations ranging from 551 mg/m3 to 3330 mg/m3 for 432 hours.

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Result: The results of xylene biodegradation showed that removal efficiency up to the concentrations of 2756 mg/m3 was 82 percent. Moreover, adding 10% silicone oil increased removal efficiency of BTX by 85.7% in comparison with context without organic phase. The microbiological experiments on the bioreactor media showed that three spices of Pseudomonas putida, Chryseobacterium and Ralstonia pickettii were found, in the presence of xylene.

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Conclusion: Overall, the results of the present research revealed that application of two phase stirred tank bioreactors (TPPBs) for xylene from contaminated treatment of streams was successful.

Introduction: The power tiller is a multipurpose hand tractor designed primarily for rotary tilling and other farm operations. Vibration, transmitted from the handles of the tiller to the operators’ body, causes many injuries such as, pain, musculoskeletal disorders and white finger syndrome. The aim of this study was to evaluate the hand-arm vibration exposure in the operators of tiller model HT900, as the most frequently used model of tillers.

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Material and Method: In this study, 40 operators tiller of model HT900 in the city of Kashmar, Khorasan Razavi were examined. Hand-arm vibration measurement was done according to ISO 5349-1 and ISO 5349-2 in three different modes including, static and neutral (mode), transition to the ground mode and plowing the land mode in different gears. In order to measure the vibrations, human response vibration meter of B and K model 2512 was utilized.

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Result: Results of the present study indicated that in all measured situations, exposure to hand arm vibration was higher than the standard limit suggested by Iranian occupational health committee and there was risk of vibration-induced disorders. The maximum exposure to vibration is in plowing ground. Exposure to hand arm vibration in three modes of plowing, transmission and natural, were respectively 16.95, 14.16 and 8.65 meters per second squared. Additionally, in all situations, vibration exposure was highest in the X-axis in comparison with Z- and Y-axes.

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Conclusion: This study emphasizes on the need to provide intervention and controlling and managing strategies in order to eliminate or reduce vibration transmitted from tiller to operators hand and arm and also prevent to serious problems including neurovascular disorders, discomfort and white finger syndrome. Meanwhile, more studies are necessary to identify the sources of vibration on different models of tiller.

Introduction: Tractor drivers are continuously exposed to whole body vibration during driving that, this may cause disorders in the system of musculoskeletal, nervous, circulatory and occupational diseases. The aim of this study was to evaluate exposed to whole body vibration among tractor driver.

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Material and Method: In this study, whole-body vibration parameters such as root mean square (rms) of acceleration , total equivalent acceleration, vibration dose value (VDV) and crest factor (CF) were separately compared in three directions (x, y, and z) , in 3 Massey Ferguson Model 165 Tractor it was done during 3 different modes of transport (without trailer, with empty trailer and with a trailer load of soil) , plowing the land and loading trailer in working conditions with various gear according to the guidelines of ISO 2631 standard.

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Result: The results showed that in all measuring points, exposure to whole body vibration was higher than permissible level and the risks of disorders exist. Exposure to vibration were as with empty trailer (43.11m/s2). The maximum of crest factor was obtained for transportation mode of empty trailer with 3 gear (10.7), then plowing (7.35) and loading soil(6.50). The maximum of vibration dose value was eventuated for transportation mode with empty trailer with 4 gear (189.92 m/s1.75) and 3 gear (108.15m/s1.75). In all measuring modes exposure with vibration in Y direction was greater than X and Z axes.

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Conclusion: This study shows that the need to provide intervention , controlling and managing measures to eliminate or reduce exposure to whole body vibration among tractor drivers its necessary. And, preventing main disorder Including musculoskeletal disorders, discomfort and early fatigue is of circular importance. More studies are also necessary to identify the sources of vibration among various of tractors.

Introduction: Every year many people around the world lose their lives or suffer from injuries and serious damages in industrial fire. This study aims at evaluating fire risk using an suitable method and determining endangered humane, financial and environmental capitals in various parts of a chemical industries.

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Material and Method: In this analytical study the developed Frank and Morgan method was used to evaluate the risk of fire in all units of a chemical company. Improved checklists validity was confirmed by experts and then, its reliability was determined by test-retest analyzing method. Human, financial and environmental probable losses were calculated in the case of fire. A risk factor was determined for each unit and all of them were prioritized accordingly.

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Result: The study of developed checklists’ validity showed that there was a high conformity (homogeneity) between results of two measured loads (ICC=0.87 %95CI: 0.699-0.952). Mean value of risk in units was 115.45 and research and development (R&D) and sparse part store units have the highest and lowest risk values, respectively. Endangered humane, financial and environmental capitals had the highest to lowest score, respectively.

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Conclusion: Results showed that the developed Frank and Morgan method can be a suitable tool for evaluating industrial fire risk and prioritizing units in general level of an industrial complex especially chemicals company. According to the findings in this study, the investigation of likely damages to environment in the case of fire has high importance.

Introduction: According to the previous studies, about 90% of accidents in the workplace are due to the unsafe behaviors. In this study, the impact of personality traits, as a predictive factor on the unsafe acts was surveyed in a construction project of a car manufacturing company.

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Material and Method: In this study, personality traits and unsafe behavior rates were determined using NEO-Five Factor Inventory (NEO-FFI) and safety behavior sampling (SBS) technique. The Spearman correlation coefficient was used. To analyze the acquired results, the total population of the project was 243 people.

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Result: The results showed that 31.7% of workers’ behaviors were unsafe behaviors. The correlation between unsafe behaviors and the neuroticism and extroversion were direct and significant (p<0.001).

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Conclusion: Assessment of the personality traits could be used as a predictive tool to identify employees with higher rates of unsafe behaviors and helps planning to reduce the accident rates.

Introduction: In real Conditions, pollution emission are mostly released as mixed components rather than a single pure emission of the chemicals. In this study, a miniature stirred tank bioreactor was optimized for treatment of waste gas containing BTX (benzene, toluene and xylene).

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Material and Method: The sludge of an oil refinery was sampled based on the assumption that it contains BTX-degrading microorganisms and used as microbial consortium. Also, silicone oil was added to improve removal efficiency. The operational parameters of the bioreactor were optimized during the study.

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Result: The removal efficiency and elimination capacity of benzene, toluene and xylene vapors simultaneously in the presence of 10% silicone oil as an organic phase showed increasing trend up to the concentrations of 1730 mg/m3, 1710 mg/m3 and 1380 mg/m3, respectively. In these concentrations the removal efficiency and elimination capacity of benzene were 100% and 59 g/m3/h, toluene 100% and 58 g/m3/h and xylene 91% and 42 g/m3/h, respectively. The total removal efficiency and elimination capacity for BTX were 91 to 100% and 159 g/m3/h, respectively.

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Conclusion: It was shown that presence of 10% silicone oil increased 44.5% in total removal efficiency of BTX. The microbiological experiments on the bioreactor media showed that three spices of Pseudomonas putida, Chryseobacterium and Ralstonia pickettii can be found, when BTX ware treated. This work revealed that two phase partition bioreactors (TPPBs) can be successful method for the treatment of streams contaminated with BTX.

Introduction: Nowadays, using multi attribute decision making (MADM) techniques in HSE hazard rating have been widely increased. On the other hand, Analytical Network process (ANP) methods has a high flexibility and accuracy in decision ranking. Therefore, the combination of the two mentioned approaches can provide a more precise prioritization for HSE hazards. Using ANP techniques, in this research a method for accurate rating of HSE hazards in the construction procedure of combined cycle power plant was presented.

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Material and Method: In this study, first, the overall structure and components of ANP method were identified and the connections between its components were determined. Then, the determined structure and components were modeled, using super decision software. In the next stage, pair companions were performed between an criteria and sub-criteria with respect to HSE experts opinions, Finally, selected HSE hazards were prioritized and compared according to the presented ANP method and the common available method.

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Result: According to the results, common risk assessment method is not able to prioritized risk accurately. While the current method classified the ten main identified hazards in 4 general categories, the presented method in this study could prioritized then in 7 categories.

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Conclusion: The suggested ANP model could provide a more accurate prioritization for hazards in comparison with current methods because of considering five qualitative indices. This allows an optimal allocation of organizational resources for controlling hazards.

Introduction: Electromagnetic field emitted by laptops are known as extremely low frequency (ELF) Waves. The aim of this study was to investigate the intensity of electric and magnetic field with extremely low frequency emitted by common laptops.

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Material and Method: Intensity of electric and magnetic field were measured on four sides of 40 common by used laptop at the distance of 30, 60 and 90 cm. Measurements ere done according to standard in four functional model including: non-performing turned on, sleep mode, performing office program and performing audio visual files.

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Result: Magnetic field values for all laptops were almost constant and about 28-32 mA/m. The results of measurements related to the electric field showed different values at distances of 30, 60 and 90 cm around the laptops on four sides. Moreover, mean electric field on the keyboard at the four operating modes were statistically different for DELL and hp laptops (P< 0/05).

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Conclusion: The results of this study showed that laptops produce extremely low frequency (ELF) electric and magnetic fields which their intensity depends on laptop type, laptop operation mode and the location of the measurement.

Introduction: Job design approach is one of the significant concepts in ergonomics Experts believe that integration of macro ergonomics and job design can lead to improved productivity in the organizations. Therefore, this study examined the relationships between job design, performance and job satisfaction.

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Methods and Materials: This cross - sectional study was done in 11 branches of one of the bank in Hamadan. Job Design Questionnaire, Job Satisfaction Questionnaires and Bank Performance Indicator were used in order to collect data. spearman correlation coefficient was used for determining the correlation between each two variables.

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Results: This study showed that the motivational approach was the minimum approach (3.8%), and the mechanical approach, was the dominant approach (74.7%) in the study branches and the majority of branches had an average level of job satisfaction. Moreover, there was a significant positive correlation between job design (motivational and cognitive approaches) and job satisfaction. In addition, the results showed that between job design (Motivational approach) and satisfaction were significantly correlated with performance, (p = 0.05).

Conclusion: Regarding the role of job design in job satisfaction and employees, performance, it can be stated that job redesign towards a motivational approach and considering the principles of ergonomics in the workplace, can play an important role in efficiency and productivity of an organization.

Introduction: Emergency situations are of the major challenges in industries. Understading the status of inter-team interaction is effective in improvement of emergency response team (ERT). The purpose of this study was to investigate the interaction space of ERP in a refinery, using the social network analysis (SNA).

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Methods and Materials: In the present case study, the density indicator was used to examine the interaction space in the ERT. The obtained data were analyzed, employing UCINET 6.0 social network analysis program.

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Results: The findings showed that the ERT has the relatively low concentration with the density of 0.2 overall, the result reflect a low level of interactions among response reams at emergency situations management.

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Conclusion: The presented approach provided an appropriate image of interactions network among the emergency response teams. The social network analysis can be used for assessing the interactions of the emergency response teams.

Introduction: The Power plants are as the major industries that have a large number of workers, providing they health is important. Exposure to occupational noise is the pervasive physical agent in industries like power plants and may impact health and for safety status for people. Determination of the sources of noise in workplaces is important step in noise control plans. This study aimed to assess noise pollution and determine the main sources of noise in a power plant for.

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Material and Method: This descriptive cross-sectional study was conducted on the ground floor of the turbine unit of a thermal power plant. Measurements was done based on the ISO-9612 and ISO-11200 standard using by the calibrated sound level meter model TES-1389 on “A” frequency weighting and “Slow” mode for time response. Surfer V.10 software was used for interpolation and noise maps producing. Based on grid method measuring for indicating of noise propagation, we set buffer of danger areas to determine main sources of noise. Also, we used the minimized grid method for measuring and study of noise denotation in vertical surface in each main sources.

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Result: The results showed that the measured indoor sound pressure level in all areas where at the risk category of the units. The highest average sound pressure level was belonged to the unit 2, with 93.1 dB(A). We find the feed water pumps were the main sources in all of the studied units. Among the four main components of the main sources, the highest noise levels associated with the main pump and the gearbox section with about 100 9B(L) and dominant frequency of 2000 Hz.

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Conclusion: Considering that feed water pumps had major sources in indoor power plant noise pollution, engineering noise control such as providing enclosures is necessary to reduce noise pollution to safe levels in the studied plant it is necessary.

Introduction: The present study aimed to test a model of the relationship between management commitment to safety and consciousness with unsafe performance,considering the mediating role of safety self-efficacy.

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Material and Method: Research design was the correlation throughStructural Equation Modeling (SEM) and the sampleconsisted of 265 employees of an industrialcompany who were selected by stratifiedrandom sampling method. Participants of this study completedsafety climatescale, short form of NEO personality questionnaire,safety self-efficacy scale, and unsafe performance questionnaire.Reliability and validity of the questionnaires were reported as acceptable. Evaluation of the proposed model was done by SEM through AMOS-21and SPSS-19 software packages. In addition, Preacher and Hayes’ SPSS Macro program was used for testing the mediating role.

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Result: The results showed that the proposedmodel fit the data properly.Management commitment to safety and consciousness had direct effect on unsafe performance and safety self-efficacy.Moreover, the mediating effect of safety self-efficacy in the relationship between management commitment to safety and consciousness with unsafe performancewas confirmed.

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Conclusion: Overall, organizations canreduce unsafe performance and consequently occupational accidentsby increasing the management commitment to safety and employees’ consciousness and also training of employees and supervisors to reinforce their safety self-efficacy.

Introduction: Resilience engineering is a new approach in safety science. Its goal is to maintain organizational capacity in an acceptable level to help system in managing the crisis. Indeed, resilience engineering rely on systems abilities instead of weaknesses, and try to find indicators that help the system durability.

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Material and Method: In this study,first, 6 resilience engineering factors were chosen and sent toexperts in the form of paired comparison sheets. On the other hand, a valid standard questionnaire distributed among drilling rigs operational workers for measuring the NIDC resilience level. Finally,the priority of corrective actionswas determinedaccording to the score of the two analyzedquestionnaires.

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Results: The results of resilience engineering factors weighting showed that the management commitment has the highest value andthe second place belonged to the correct culture. The indicators’scores,based on the distributed questionnaires among workers, showed that all of the six factors had similar scoreswhich can be evaluated as fairly good. Finally, the results of prioritization of indicators ofresilience engineering, basedon the combination ofthe questionnaire and experts opinions showed that management commitment is the most effective resilience factor in the organization. .

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Conclusion: Management commitment and the current culture are the most importantcontributing factorsin company resilience level. Experienced workforce was the best strengthof the company and the effect of financial issues on resilience and safety was the biggest problem ahead.

Introduction: Children have been known to spend most of their time at school. They learn their sitting habits in this period of time. Incorrect sitting postures and inappropriate school furniture can result in abnormalities in the vertebral column, back pain, neck pain, Fatigue and discomfort. Hence, this study was aimed to examine the match between students’ body dimensions and existing benches and desks dimensions in Hamadan female primary schools.

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Material and Method: In this study, 624 students of Hamadan female primary schools were investigated and some of their anthropometric dimensions including shoulder height, elbow height, knee height, popliteal height, popliteal-buttock length and hip breadth were measured. In this sense, a chair (with adjustable height, depth and elbow support) and a caliper with movable jaw were used for measurement of anthropometric dimensions. The measurements were performed in a way that thighs were in full contact with the seat, there was a right angle between the thighs and legs, the feet were in full contact with the movable pedal, the trunk was straight and the back and hips were in full contact with the backrest. Following, the match of the dimensions of existing benches and desks with the appropriate dimensions (based on the students’ anthropometric dimensions) were examined.

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Result: The results showed that the seat height, seat depth, seat width, back rest height, desk height, underneath desk height were in acceptable rangefor 10.1%, 17.3%, 5.6%, 53.5%, 1.9% and 31.1% of students, respectively.

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Conclusion: Despite differences in the body dimensions of primary school students, there is no regularity in using of school furniture. Overall, the dimensions of existing benches and desks are not matched with the anthropometric dimensions of students.

Introduction: The bank employees usually require the use of computers for long duration in a static position to get the work done. The present study aimed to evaluate the risk factors for musculoskeletal disorder using the ROSA method among the employees of Sepah Bank. An ergonomic intervention was also performed in order to improve the working conditions.

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Material and Methods: This interventional descriptive-analytical study was carried out among 165 office employees of central building of Sepah Bank. Using random sampling, the subjects were initially divided into two groups of case and control. Before and after the intervention, ROSA method and Nordic questionnaire was respectively used to evaluate the risk factors that cause musculoskeletal disorders and the prevalence of musculoskeletal disorders. The data were collected two weeks prior the interventions and 9 months after the interventions. SPSS software version 16 was utilized for data analysis and the effectiveness of intervention was determined.

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Results: Before the intervention, the mean ROSA scores of all groups' workstations were above 5 with high risk. The results obtained 9 months after the interventions manifested a statistically significant decrease (P<0.001) in the ROSA mean scores and its components in the groups who received the interventions. 9 months after the intervention, the prevalence of musculoskeletal disorders among the subjects who had received intervention showed a significant reduction, as well (0.001> p).

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Conclusion: Using the ROSA technique was seemed to be beneficialto assess the ergonomic risk factors of office works, and the deficiencies in the workstation can be identified through this method. Moreover,by design and implementation of an educational intervention program along with engineering interventions which comply with the elements of this technique, the defects can be eliminated.

Introduction: Studies have shown that bank clerks experience high levels of stress. Stress is known as the main cause of reduction of job satisfaction and staff commitment and overall organization performance. This study aimed to investigate the association between psychosocial stressors, organizational structure, and job satisfaction.
 

Methods and Materials: This cross-sectional study was performed in 11 branches of a bank in Hamadan. In order to collect data, General Nordic Questionnaire (QPS Nordic 34+), Organizational Structure and Job Satisfaction Questionnaires were used. For determining the relationship between the two variables spearman correlation coefficient was used. Moreover, chi-square test was used to investigate the association between qualitative variables.
 

Results: Job stress (57%) and job satisfaction (39%) of the subjects were in the average level, and structure of the majority of the branches was somewhat inflexible (69%). What is more, there was a significant positive correlation between job stress and dimensions of organizational structure (centralization, formalization). Results manifested a significant correlation between organizational structure and job satisfaction (P-value= 0.05).
 

Conclusion: Considering the effect of organizational structure and work-related psychosocial stressors on job satisfaction, it can be stated that organizational restructuring to achieve organic structures and paying more attention to psychosocial stressors in the workplace, can play an effective role in the efficiency and productivity of the organization.

Introduction: Traffic noise has been thought as a major environmental stress in modern societies, and the cause of physiological and psychological disorders according to the World Health Organization. Moreover, traffic noise can interfere with mental performance. However, there is little coherent evidence showing the effect of traffic noise on individuals’ performance. Hence, this paper aimed to address the role of traffic noise in participants’ mental performance considering the complexity of the activity.
 

Material and methods: Thirty-five master students studying in Tehran University of Medical Science were recruited for this study. Traffic noise was recorded by tape recorder and the traffic noise level was simultaneously measured by sound meter. Then, participants had been separately sitting in silent compared to traffic noise environment before they performed the tests including “S₃”-type Choice Reaction Time (CRT) test as a simple activity and “S1”-type Determine Test (DT) as a complex activity taken from “Vienna Test System” software package.
 

Results: The comparison between scores resulted from DT and CRT tests ,before and after exposure to traffic noise under simple activity conditions, showed that there was little increase in mean score of reaction time (P-value=0.47) and motor time (P-value=0.49), showing no statistically significant changes in these variables. On the contrary, following exposure to traffic noise, the DT test under complex activity condition revealed that there is a clear decreasing trend in median reaction time(P=0.001), number of stimuli (P=0.014) and number of reactions (p=0.009) in participants, and also, no significant differences were found in correct responses (P=0.091) and incorrect responses (P=0.073).
 

Conclusion: One of the most significant findings emerged from this study is that traffic noise seems to have no effect on the mentioned variables under simple activity condition. However, traffic noise has devastating effects on median reaction time, number of appeared stimuli and reactions under complex activity condition.