Journal of Health and Safety at Work

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Introduction: Exposure to vibration as one of the consequences of industrial noise or the use of vibration generators can cause discomfort, reduce the efficiency and level of safety in workplaces. Therefore, in this study, the effect of whole body vibration on individual’s mental performance and response time was investigated.

Material and Method: In this study, 40 male students of Tehran University of Medical Sciences were selected randomly and divided into two 20 subjects groups. Each group participated in two Pegboard Board and Math Calculations tests. Subjects in each stage of test were exposed to whole body vibration with acceleration in 0.8 and 1.1 m/s2 as well as background mode without vibration and were investigated response time and mental performance.

Result: In the present study, the mean response time to the manual Purdue Pegboard test in the vibrational acceleration of 0.0, 0.8 and 1.1 m/s2 with a decreasing trend was 197.55 ± 2.7, 176.25 ± 5.38 and 177.58 ± 2.92, respectively, which results in a significant reduction in the accuracy of the test. Also, the results showed that whole body vibration does not affect mental performance in shallow levels. But, in the intermediate and deep levels, this difference is statistically significant (p <0.001).

Conclusion: Based on the results, whole body vibration is an effective factor in individual’s response time and mental performance, which can lead to a reduction in the accuracy of the work.

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Introduction: Job stress is one of the occupational hazards in the modern era. The National Institute for Occupational Safety and Health introduced the nursing job as a top 40 stressful jobs. In this job, multiple training techniques are considered to reduce stress and stress factors. This study was conducted to response the question “Is the use of health education programs can be effective in reducing job stress?”

Material and Method: Electronic search was done using key words in Persian and English database (Medical Sciences, Iran Medex), Scientific Information Database (SID), Bio Med Central, Pub Med, Science Direct) and were found 3,412 paper totally. Articles examined based on defined criteria and 9 qualified articles were discussed systematically.

Result: Among the reviewed studies, educational interventions in 7 studies were without, and 2 studies were with the use of health education models. The results of studies indicated significant effect of educational interventions on reducing job stress and using health education models in interventions had a greater effect on reducing job stress.

Conclusion: The results highlights the importance of educational interventions based on health education models to reduce occupational stress among nurses.

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Introduction: Electrospun nanofibers are suitable option to synthesize filtering mats for nanoparticles. This study was aimed to fabricate polyurethane nanofiber mats through electrospinning process and to investigate the effect of different parameters such as packing density, face velocity and particle type on the filtration efficiency and quality factor of electrospun polyurethane nanofiber mats.
 

Material and Method: The nanofiber mats were produced by electrospinning  process. Polyurethane granules were dissolved (15w/w%) in a solvent system consisting of dimethylformamide and tetrahydrofuran (3:2). Then, the filtration performance testing system was made at the Fluid Mechanics Department of Hanyang University of South Korea and the filtration efficiency and pressure drop of prepared nanofiber mats were studied.
 

Result: Findings showed that by increasing the duration of electrospinning, the basis weight, thickness, packing density, initial pressure drop and filtration efficiency of the mats increased, and the quality factor of the mats decreased due to the increase of the pressure drop. The increase in electrospinning duration from 15 to 45 minutes was led to the increase in pressure drop from 7 to 32 Pa and the average filtration efficiency was increased about 9-10% for KCl and DEHS test particles. The filtration efficiency and quality factor of the prepared polyurethane nanofiber mats were declined with the increase of filtration face velocity from 2 to 5 and 10 cm/s. The reduction in filtration efficiency was more obvious for particles smaller than 425 nm.
 

Conclusion: The results demonstrated that prepared polyurethan naofiber mats provide acceptable filtration performance. What is more, such nanofiber mats can have other potential benefits such as light basis weight, low thickness and simple production.

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Introduction: Adverse effects of volatile organic compounds (VOCs) including general and specific effects like carcinogenic of benzene are well known. The aim of this study was to evaluate occupational exposure to BTEX compounds in the painting unit of an automotive industry and subsequently health risk assessment of exposure to these compounds.

Material and Method: This cross-sectional study was conducted in the paint unit of an automotive industry including painting cabin, pre-painting salon and painting salon sections. After analyzing samples, gathered from different sections, by GC-MS, BTEX compound were identified as the main contaminants. In the next step, NIOSH1501 and EPA methods were used to measure and analysis of BTEX and risk assessment, respectively.

Result: Findings showed that benzene concentration in painting cabin was higher than occupational exposure limits provided by the Environmental and Occupational Health Center of Iran. Life time cancer risk for benzene per 1000 has been reported10, 3.63 and 1.27in the painting cabin, pre-painting and salon sections, respectively. It was also for ethyl benzene 2.5m 1.8 and 38.0 in the mentioned sections, respectively. The non-cancer risk for benzene and xylene in the painting cabin and pre-painting sections were higher than recommended allowable level.

Conclusion: Regarding the high level of cancer risk values obtained for benzene and ethylbenzene in the studied units and also high values of non-cancer risk for benzene and xylene, it is recommended to conduct biological exposure assessmnet of the workers and improve existence control systems using modern engineering control systems.

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Introduction: The responsibility of achieving sustainable development goals in most megacities and subsequently in Tehran megacity are in charge of the municipalities. Since, the goal of municipalities in environmental-friendly activities is to protect the physical and mental health of citizens. Therefore, the sustainability assessment of health performance in municipalities is one of the most significant issues in the field of municipal sustainable development of megacities. The Objective of this study was to develop a tool for assessing the sustainability performance of Tehran municipality in the field of health- related activities and services.

Material and Method: In this research the main sustainability indicators in the field of health performance were extracted and localized by providing an indicator-based tool for Tehran municipality as a case study. To determine the initial set of effective indicators, guidelines and standards related to health sustainability issues were surveyed, and an initial set of indicators were extracted. Afterward, a two-round Delphi method was applied by 12 qualified experts to select the most robust indicators of Health performance and assign the importance of the inclusion for each proposed indicator on a seven-point Likert scale. The mean value set to 70% and the standard deviation less than 1 were considered as the cut value.

Result: The findings resulted in extracting 11 main categories and 28 sustainability indicators of health performance. The set of indicators related to the “green space” and “waste” categories with slight differences gained the first and second position in the health sustainability field respectively, whereas “urban planning”, “active and healthy life” and “health and hygienic services” located in the bottom of the list with the relatively close scores.

Conclusion: The results of this study showed that due to little difference between the score of the main selected categories (less than 1 point difference between the highest and lowest categories) and also due to the fact that the expert panel reached a consensus on the total 11 categories, therefore  in order to achieve municipal sustainable development and improving the health level of citizens in the future, it is essential to have a robust consideration toward applying engineering and management measures against all 11 selected categories.

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Introduction: Considering the necessity of evaluating novel thermal indices for different individual and environmental conditions, the aim of this study was validation of a new enthalpy index for evaluation of heat stress in hot and dry climate.

Material and Method: In this descriptive analytical 97 city services outdoor workers were randomly selected and evaluated in spring and summer seasons in Qom city, Iran. Correlation between new enthalpy index and standard WBGT index, as well as physiological response of deep body temperature was studied and analyzed.

Result: Findings showed that regardless of the time of measurements, correlation between enthalpy and WBGT index was better than its correlation with tympanic temperature (R2= 0.756 versus R2= 0.391). Considering the time of measurement, it was found that with increasing temperature and decreasing humidity, the correlation between indices was reduced, although the correlation ratio was maintained similar.

Conclusion: Due to the simplicity of the enthalpy index measurement ,its independency to measure the globe temperature and the possibility of estimation of this index using daily climate parameters in meteorological stations, and on the other hand, appropriate validity of enthalpy against WBGT and core temperature, it can be a good alternative for WBGT index and as a screening index for thermal environments in hot and dry condition.

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Introduction: Anesthetic gases used in hospitals include N2O and halogenated hydrocarbons (such as sevoflurane) which can be released through leakages and uncontrolled exhalation by the patient into the ambient air of clinical staff. These gases have greenhouse effect and damage to the ozone layer and serious risks such as reproductive, preterm delivery and fetal abnormalities and increased spontaneous abortion on the health of operating room personnel. Therefore, removal of these gases from the workplaces is essential especially in the treatment centers. The purpose of the present study was to investigate the adsorption of sevoflurane from air by using activated Charcoal and also the effect of acid modification on its performance.
 

Material and Method: In this study, two adsorbents of unmodified and modified activated charcoal with nitric acid were used to remove sevoflurane. After preparation, the adsorbents were characterized using XRD, FT-IR, BET and FE-SEM methods. After characterization, the breakthrough and adsorption capacity of sevoflurane on both adsorbents were determined using the modified wheeler equation.
 

Result: The results of characterization showed that acid modification did not affect the crystalline structure of activated charcoal and increased the adsorption and microporous of acid-modified activated charcoal in comparison with unmodified activated charcoal. It also reduces surface functional groups of the activated carbon. The results of determination of adsorption capacity indicated that the adsorption capacity of modified activated charcoal was improved in comparison with unmodified activated charcoal.
 

Conclusion: The results demonstrated that both adsorbents have the ability to absorb sevoflurane and modified activated charcoal have a better performance in this process. This effect may be due to the surface area of adsorption and volume of micro pores more than the unmodified activated charcoal.

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Introduction: Impairment of alertness, attention and performance associated with sleepiness and fatigue in nurses occur in night and long-term shifts that in the end of night shift reach to the maximum level can lead to traffic accidents when they returning home. The purpose of this study was to determine the effect of night shift on psychomotor abilities of driving in nurses after shiftwork.
 

Material and Method: A cohort study was carried out on 23 night shift and 24 day shift female nurses aged 20 to 40 at Sina Hospital in Tehran city, using the Vienna Test System (VTS). The concentration and selective attention, reaction time, pheriperal perception, and coordination before and after night and day shifts were measured. A multiple linear regression model and Backward stepwise selection method was used for analyses.
 

Result: In the concentration and selective attention test, sum hits  (p = 0.038) and in the visual perception test , divided attention (p =0.006) and visual field (p =0.019), and in the  reaction time test the mean motor time  (p =0.034) showed a significant adverse relationship with working in night shift, but the visomotor coordination variables did not show any significant correlation.
 

Conclusion: The results showed that the concentration and selective attention, peripheral perception, and reaction time of psychomotor ability of driving were significantly adversely impaired in nurses after night shift. These results in evidence of the mechanism of increasing traffic accidents after night shift among nurses added to the previous studies in this subject.

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Introduction: Using diesel generators is necessary for activities like welding in construction sites and it is often accompanied with noise pollution. The aim of this study was to evaluate noise pollution induced by diesel generators in construction activities in one of the districts of Tehran city.
 

Material and Method: In this descriptive study, 14 construction sites were selected for the evaluation of noise pollution in Tehran, district 4. Background and diesel generators sound pressure level were measured in accordance with BS 5228(2015) and noise guidance in the area around the construction sites. Diesel generators sound pressure level at 4 points and also the audio frequency analysis, one meter away from the device was measured at a random locations around it. TES-1358, Type 2(Taiwan) sound level meter was used to measure sound pressure level and calibration was performed before and after noise measurement. The validated Noise annoyance questionnaire adopted from ISO15666 standard, completed by the residents. T test, correlation and analysis of variance was performed to analyze data using SPSS software ver. 22.
 

Result: The mean equivalent sound level of diesel generators background noise were respectively 76 ± 4.05 dB(A) and 46.2 ± 1.09 dB(A) around the construction sites. Diesel generators noise around the construction sites was higher than the noise limit (background noise plus 5 dB)(P Value <0.05). The highest (95.3 ± 0.33 dBA) and lowest (90.9 ± 0.63 dBA) average sound pressure level was related to Benz355 and Perkins generators. One-way ANOVA statistical analysis showed significant differences in the average sound pressure level of various diesel generators between the devices (P Value <0.05). The mean sound pressure level among 190 sound monitoring stations in the interior parts of the construction sites were about 81.11 ± 4.6 dB(A). The experienced noise annoyance was evaluated higher than the average by 73.4 percent of residents. Residents’ noise annoyance and noise level around construction sites were significant using Pearson correlation (R=0.486, P value <0.05). Dominant noise frequency and associated sound pressure level of diesel generators were measured 63 Hz and 84.4 dBA, respectively.
 

Conclusion: Diesel generators noise in the area around the construction sites was higher than the environmental noise limit and it was accompanied with abundant noise annoyance for residents around these construction sites. Therefore, due to the lack of environmental rules related to construction industry noise pollution in Iran, assessment and approving of such rules is essential to reduce noise annoyance in urban areas.

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Introduction: Mercury, in different form can induce adverse effects on various organs especially central nervous system. The aim of this study was to determine concentration of mercury in inhalation and urine of the exposed worker and to investigate the prevalence of probable neurobehavioral disorders.
 

Material and Method: The present case-control study was conducted among workers of a unit in a petroleum industry. The study population consisted of 52 workers as case and 63 workers as control groups. The mercury concentration in air and urine was measured according to NIOSH 6009 standard and using the cold vapor atomic absorption spectrophotometer (CV-AAS). Demographic data and neurobehavioral disorders were collected using a self-reported questionnaire. Pearson correlation coefficient, multiple regression tests and SPSS v24 were used to analyze the data.
 

Result:  Air concentration of mercury was 0.062 ± 0.0014 mg/m3  which was higher than the recommended threshold by NIOSH and ACGIH. In addition, there was a significant difference between urinary concentration of mercury in the case (37.73 ± 13.01 µg/g cratinine) and control (5.93 ± 4.76 µg/g cratinine) groups (p=0.03 6). Based on the multivariate logistic regression model, significant relationships were found between memory loss, sleep disturbance, and urine mercurial concentrations and, between memory loss, moody, muscle weakness and air mercurial concentration.
 

Conclusion: The values of Hg in blood and urine workers who worked in investigated unit were significantly higher than recommended threshold values. In addition, the Hg concentration in urine was related to some of neurobehavioral disorders.

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Introduction: Workers in open pit mines are frequently exposed to extreme heat stress during hot seasons. Several indices including Modified Discomfort Index (MDI) are used to evaluate the heat stress. The aim of this study was to evaluate the MDI and to investigate its relationship with ISO 7243 standard (Wet Bulb Globe Temperature index, WBGT) and physiological parameters of workers in an open pit mine.
 

Material and Method: This cross-sectional study was conducted among 120 healthy male miners in an open pit mine during summer season in 2014. Physiological parameters including body core and skin temperature, heart rate and blood pressure were measured according to ISO 9886 standard. All environmental and physiological parameters were simultaneously measured and recorded during a work shift. The MDI and WBGT indices were calculated using the related formula. Statistical analysis was performed using the SPSS 22 software.  
 

Result: According to the criteria of MDI, about 29 percent of workers had the average level, 68 percent of workers experienced the intense level and 2.5 percent suffered from the extreme level of exposure to the heat stress. No case of light level exposure to heat stress was obtained among workers. A significant correlation was found between MDI and ISO standard index (WBGT). Statistically significant correlation were also found between MDI and physiological parameters (P<0.001); in which the highest correlation coefficient was found for the heart rate variable (r=0.589).
 

Conclusion: Based on MDI, a high percentage of open pit mine workers were at risk of heat stress hazards. MDI had a moderate correlation with physiological parameters of the workers and showed a remarkable correlation with the WBGT.

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Introduction: Chronic occupational noise exposure may constitute a risk factor for cardiovascular disease for workers. The aim of this study was to investigate the relationship between occupational noise exposure and noise annoyance with blood pressure, serum cholesterol and triglyceride levels in workers of a textile industry.

Material and Method: This cross-sectional study was carried out among 220 employees of Savadkouh textile industry complex in Mazandaran province, Iran in 2017. To achieve the study objectives, the 8 -hour equivalent sound exposure level was measured and the cumulative noise exposure was calculated. Based on noise exposure level, workers were divided into control and case groups. Then, blood pressure was measured and blood samples were collected from each individual for determination of the serum cholesterol and triglyceride levels and they were transfered to the laboratory for further analysis. The noise annoyance scale and socio-demographic questionnaire were used to collect noise annoyance and other background and demographic information, respectively. Finally, Paired t-test, one-way ANOVA and multivariate regression were used to study the relationship between variables using SPSS Version 20.

Result: In total, 159 workers participated in this study considering the inclusion and exclusion criteria. Eighty-three participants were exposed to more than or equal to 85 dBA, and 76 person were exposed to less than 85 dBA noise level, respectively. The results showed that mean blood pressure and cholesterol were significantly different between the control and case groups (P-value< 0.05). Based on multivariate regression results, noise exposure, cumulative noise exposure (CNE) and noise annoyance had a significant effect on blood pressure (P-value< 0.001).  Cholesterol was also significantly affected by noise exposure and noise annoyance (P-value< 0.005).

Conclusion: Based on the results of current study, noise can be considered as a risk factor for cardiovascular disease ampong workers. Actually, high intensity noise affect serum cholesterol and blood pressure directly, and may do indirectly by causing noise annoyance which acts as a mediator. Therefore, it seems necessary to conduct a controlled cohort study to investigating the interactions among whole variables of interest.

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Introduction: Indoor air environments contain a wide variety of microorganisms such as bacteria, fungi, and viruses in which some of them can affect the human health. Filtration is considered as one of the most common methods to remove microorganisms in these environments. The purpose of current study was to investigation the neat and photocatalytic HEPA filters performance at different face velocities and various intensity of UVC light source on the reduction of airborne microorganisms.

Material and Method: After installation of the neat and photocatalytic HEPA filters in a closed–loop chamber, suspension of Staphylococcus epidermidis and Bacillus subtilis bacteria with a concentration of 107 CFU / ml were sprayed into the closed–loop chamber by nebulizer. Sampling of penetrated microorganisms from filters were performed using the NIOSH 0800 method under ambient temperature 22±3oC, relative humidity 35±5%, and different air velocity (0.1 m/s and 0.3 m/s) and UVC different radiation intensity (1 mW/cm2, 1.8 mW/cm2 and no radiation (dark)) at 30 minutes time period. penetrated microorganisms density from filters was determined in term of CFU/m3.

Result: There were no significant differences in the penetration rates of microorganisms at the dark mode between the two neat and photocatalytic HEPA filters (p>0.05). The penetration rate of bacteria was significantly decreased in the neat and photocatalytic HEPA filters at UVC radiation mode with various intensities than dark mode (p<0.05). In addition, comparison of the filters in the illuminance modes of 1 mW/cm2 and 1.8 mW/cm2 were statistically significant (P <0.05). Also, UVC radiation with the 1.8mW/cm2 illuminance compared to the 1 mW/cm2 illuminance resulted in a greater reduction in the bacterial penetration from both types of filters, which is statistically significant(p<0.05). The bacteria penetration rate dramatically increased by increasing the face velocity from 0.1 m/s to 0.3 m/s under UVC radiation at an illuminance of 1mW/cm2, 1.8mW/cm2 and as well as in no radiation mode in both types of HEPA filters (P <0.05).

Conclusion: Photocatalytic HEPA filters and increasing UVC illuminance, especially at lower surface velocities, have a significant positive effect on reducing airborne microorganisms and increasing the efficiency of HEPA filters

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Introduction: Risk assessment is a main tool in safety management process as it can help managers to choose corrective actions by providing appropriate information. The purpose of this paper was to select the optimal corrective actions among the proposed ones by the experts based on mathematical modeling, taking into account the standards and also the limitations including the cost.

Material and Method: In this paper, a model was presented to find the optimal corrective actions regarding the organization goals (maximum in risk reduction value) and the limitations such as cost and level of acceptable risk. Due to extensive number of solutions, Genetic Algorithm (GA) is used for solving the problem.

Result: To show the capability of this method in an industrial environment, a power generation industry with 40 hazards was considered as the case study. Then, the risk of hazards was estimated and corrective actions were determined for each of them. Using the proposed model, corrective actions were selected optimally, with the least possible cost; all risks were reduced below the level of organizational acceptable risk.

Conclusion: It was shown that the optimal corrective actions using mathematical modeling are selected with high precision in acceptable time. This method is suggested as an alternative for conventional qualitative methods based on expert’s opinions.

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Introduction: Examining the effect of bus drivers’ demographic characteristics as well as workplace conditions on their traffic behavior and performance is important not only for drivers’ health and safety, but also for the safety of bus passengers. The aim of this study was to investigate the relationship between demographic variables and work shift schedule on the behaviors pertaining to “hazard monitoring”, “relax driving”, “fatigue proneness”, and “thrill seeking” among intercity bus drivers.

Material and Method: In this cross-sectional study a sample of 321 bus drivers were randomly selected from Tehran intercity bus terminals. The BDRI questionnaire was used to collect data. The Pearson’s correlation coefficient and the ANOVA and Tukey’s HSD tests were used to analyze the data.

Result: In general, the findings showed that age, driving experience and rest time period positively correlate to lower fatigue, lower thrill seeking and more relaxed driving. Drivers with higher vehicle age were found to perform worse than others in hazard monitoring and to be more prone to the stress and fatigue. Also, fatigue and relaxed driving were significantly related to the marital status and cigarette usage. In addition, drivers who were college graduate or above were found to perform worse than other drivers considering all of the four factors. Furthermore, those who drive in mountainous routes were found to perform worse than other drivers in hazard monitoring and fatigue proneness.

Conclusion: Since the age and driving experience were found to influence fatigue proneness, hazard monitoring and relaxed driving, thus, setting up specific training courses for different driver age groups aiming to enhance their awareness concerning on managing these factors might help drivers improve their performance in these factors. Furthermore, regarding the effect of rest period and route type on the drivers’ fatigue and hazard monitoring ability, appropriate regulations are needed to mitigate the effect of these factors on the performance of drivers.

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Introduction: Driving a train is one of the high demand job due to high vigilance task requiring the ability to long periods monitor surrounding environment and recognizing signals. The aim of this study was to assess train drivers’ mental workload using heart rate (HR) and heart rate variability (HRV) indices.
Material and Method: An experimental design was conducted among 12 well-trained subjects to induce two different levels of mental demands in a metro simulator and to monitor mental workload levels while driving the train. The HR and HRV parameters were recorded and analysis using ECG signals.
Result: The HRV parameters including SDNNIX (p-value=0.01), RMSSD (p-value=0.00), %PNN50 (p-value=0.01), SDNN (p-value=0.07) and LF/HF Ratio (p-value=0.04) were significantly reduced in a normal operation task comparing to the abnormal one.
Conclusion: The HR and HRV (SDNN, SDNNIX, RMSSD, %PNN50 and LF/HF Ratio) were found to be sensitive to mental workload in metro train driving .It is recommended to include the HRV parameters for mental workload assessment of train drivers.

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Introduction: Disasters, incidents and crises are complex and controversial issues for the industries and organizations. Organizational resilience is an effective goal that continuously helps the organization’s performance throughout business, disasters and critical situations. Therefore, the present study aimed to investigate the validity and reliability of organizational resilience questionnaire in dealing with major accidents.
Material and Method: The present study was a descriptive-analytic study. At first, the concept of organizational resilience and its dimensions were determined for the review. Then, for evaluating the content validity, the designed questionnaire was distributed among members of the expert’s panel and the Content Validity Index (CVI) and Content Validity Ratio (CVR) were calculated based on the comments. The reliability of the questionnaire was determined after completing it by 272 employees of the studied industries.
Result: The CVR was higher than the standard value (0.50) considering all items. Also, all dimensions of the questionnaire, except for the responsibility dimension the CVI’s were above 90%. Cronbach’s alpha coefficient for all questionnaire dimensions except for the responsibility dimension was higher than the acceptable value (0.70). This coefficient for the whole questionnaire was 0.967 indicating that this index was in excellent level.
Conclusion: The findings showed that the organizational resilience questionnaire in dealing with major accidents had an acceptable validity and reliability and in order to examine the organizational resilience in organizations, it could be used as a comprehensive, strong and reliable tool.

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Introduction: Changing the national System of Classification and Labelling of Chemicals to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is beneficial for all the industries of the countries, their workers and the general public. Increasing the awareness of chemical hazards, improving the safety uses, reducing chemical accidents, and providing better conditions for emergency response in the event of chemical accidents, are some of the most important benefits of the GHS. Present study aimed to develop a tool for assessing the awareness level of chemical related personnel using the GHS and current status.  
Material and Methods: By reviewing the literatures, the GHS Guide, available sources and consultation with experts, two questionnaires were developed to assess the level of awareness of chemical related personnel and current statue. The two designed questionnaires included personal information, multiple choice questions and questions related to safety signs. The face and content validity was conducted using the experts’ panel assessment. The face validity, content validity ratio (CVR) and content validity index (CVI) were all calculated for each question.
Results: Content Validity Ratios (CVR) and Content Validity Index (CVI) were calculated for each question. The general clarity, general fit and general simplicity of the awareness questionnaire (questionnaire number 1) were obtained 0.87, 0.91 and 0.77, respectively. The mean content validity index and the mean content validity ratio were obtained 0.85, 0.85, respectively. The overall clarity, overall fit, and the general simplicity of the current status questionnaire (questionnaire number 2) was 0.92, 0.89 and 0.93, respectively. The mean content validity index and mean content validity ratio were obtained 0.92 and 0.81, respectively.
Conclusion: The two questionnaires used to assess the awareness level of chemical related personnel and current statue of GHS, were identified as valid instruments and therefore is recommended as a valid tool for future studies.

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Introduction: Todays, the improvement and optimization of the safety performance are essential and important for control and prevention of accidents in the industry. The purpose of this research was to assist a hybrid cycle power plant for identification and prioritization of the influencing factors in enhancing safety in order to reduce risks and to improve system performance.  
Material and Methods: In this descriptive-analytical study, influencing factors were classified within three main categories of human, equipment, and managment, and 14 sub-factors was screened and selected by experts using Fuzzy Delphi method. Then, fuzzy DEMATEL method was adopted to determine the relationships, the intensity of affecting and being affected factors, and the analytical network process method for weighting and prioritization the factors.
Results: The findings of the fuzzy DEMATEL method showed that “Managerial”, “equipment” and “human” factors are respectively influencing factors on the improvement of safety performance. “Managerial factors” is the most influencing and “Human factors” is the most influenced one. Based on the results of fuzzy analysis network process method, “human factors” is the first priority among the main factors, and “employee motivation”, “system of control and prevention”, “work team spirit”, “individual skills” and “Individual protection equipment” sub-factors are respectively the first to fifth priorities were according to their weight.
Conclusion: “Human factors” re the most influenced factor and the main problem of the organization, which can be improved by the most influencing “managerial” factor. The success or failure of the safety performance in the power plant depends on better management of the “human factors” and managers need to motivate employees to improve safety performance.

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Introduction: Physical workload is one of the main risk factors in developing of musculoskeletal disorders in construction workers. The current study was carried out to determine the prevalence of musculoskeletal disorders and its relationship with demographic characteristics and physical work load index (PWLI)in construction workers.  
Material and Methods: This investigation was a descriptive and cross-sectional study in which 162 subjects including 75 rebar and 87 bricklayer workers were participated. Nordic musculoskeletal and physical workload questionnaires were employed as the tools of this study. Chi-squared and logistic regression tests were used for statistical analysis in SPSS 21 software.
Results: The mean of age and working experience of construction workers were 34.6±8.6 and 11.2±6.8 years, respectively. The most prevalent symptoms were in the body regions of upper back (57.4%), lower back (35.8%), and neck (30.2%). In the univariate analysis, the musculoskeletal symptoms of shoulders, low back, feet, knees, and thighs with PWLI and the upper back pain with age, working experience, and working hours had significant relationships (P<0.05). According to logistic regression analysis, with the increase of the value of PWLI to more than 90 percentile, the chance of having symptoms of musculoskeletal disorders in low back, knees, and feet and also with the increase of working hour to more than 8 hours, the chance of having symptoms in low back and feet increased significantly.
Conclusion: The prevalence of musculoskeletal disorders was high in the studied construction workers. Most of the musculoskeletal symptoms were correlated with PWLI. Therefore, PWLI could be used to determine the construction jobs with the high risk of musculoskeletal disorders. To reduce the symptoms of musculoskeletal disorders in construction workers, the reduction of sources of physical workloads such as heavy material handling and awkward postures are proposed. It is also recommended that the working hours be limited to less than 8 hours.