Journal of Health and Safety at Work

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Introduction: Noise is one of the most common health hazards at the workplaces that can cause not only somatic problems, but also adversely affect mental health. The aim of this study was to investigate and evaluate occupational noise exposure and noise annoyance in one of the petrochemical companies.

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Material and Method: The study population included 47 people working in Administrative and Manufacturing parts of the petrochemical company. First, dosimetry of production workers and noise frequency analysis of Administrative employees were performed. Then, self-report questionnaire for the assessment of noise annoyance at workplace was completed by the subjects. The questionnaire consisted of three parts: scoring of the noise intensity in the workplace, scoring of the noise annoyance in the workplace and determining the feelings and emotions (e.g. fatigue, sleepiness, and concentration problems) that experienced by subjects during the working day.

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Result: The results of noise dosimetry measurements showed that mean eight hour equivalent continuous A-weighted sound pressure level was 86.13 dBA. According to the frequency analysis of office rooms, mean noise level and Preferred Noise-Criteria (PNC) was 69.4 dBA and 62 dB, respectively. The findings of our analysis revealed that 17.9% of administrative staff and 63.2% of manufacturing workers assigned “very high” score to the noise intensity in the workplace. The annoyance score was obtained “very annoyed” by 10% of employees of office section and 42% of manufacturing workers. For noise-related complaints and sensations defined by subjects, 49% of administrative staff and 60% of manufacturing workers marked the “sometimes” and “more” item of the questionary.

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Conclusion: Based on the obtained results of investigating the noise level (objective exposure) as well as the noise annoyance (subjective exposure) at the studied company, it is necessary to adopt the management –technical noise reduction measures at manufacturing sectors as the personal noise exposure and environmental noise exposure and also noise personal exposure of administrative staff can be decreased.

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Introduction: Heat stress is considered as one of the hazardous occupational agents in hot environments. Working under heat stress condition may lead to individuals’ health problems. Several studies have been shown that stress in the working environments can elevate stress hormones such as cortisol. Since heat stress is one of the serious stresses in hot industries including melting, this study was done to investigate the effect of heat stress on the cortisol concentration of workers in one of the melting industries.
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Material and Method: In this cross-sectional study, 70 workers in two groups of case and control (35 people in case group from foundry unit and 35 people in control group from casting unit without heat stress) were investigated. First, a demographic questionnaire was complete for each subject. Then in order to evaluate the changes in cortisol level, blood samples were taken from the participants during their working hours (9:30 to 10 AM) and the obtained levels were compared with the normal level of cortisol, provided at 7 to 10 AM. In order to assess environmental condition, WBGT (Wet Bulb Globe Temperature) index was measured at three highest including feet, waist and head. Moreover, noise and lighting were measured at the workers work station. Data were analyzed using SPSS software version 16.
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Result: Regarding WBGT, it was shown that mean WBGT index were 33 C and 16.7 C in case and control groups, respectively. Additionally, cortisol concentration in case group was significantly higher than control group (P<0.001).
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Conclusion: Results of the present study indicate that physical stresses of working environment can lead to changes in physiology of human body. Thus, variations in hormone level in its consequences in hot environment should be considered in occupational hygine.

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Introduction: Working in hot and inappropriate climate condition is one of the most common problems of occupational health which can lead to heat induced diseases and even death. Heat stress may impair the cognitive processes involved in decision-making and converting simple tasks to complex ones. The aim of present study was to assess selective attention and reaction time among workers in a casting unit of a car manufacturing industry and to investigate the effects of heat stress on mentioned variables.

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Material and Method: In this retrospective cohort study 70 workers from a hot industry were selected in two of exposed and control groups. First, demographic questionnaire was completed for each of the participants and noise and light were measured as the likely confounding factors. Stroop test 1, 2, and 3 were done before and during the work in order to determine the effects of heat on selective attention and reaction time. Besides,WBGT were measured at the ankle, waist, and head levels. Data were analyzed using SPSS software, version 18.

Result.: WBGT measurements showed that the mean WBGT were 33 and 16.7 for the exposed and not exposed groups, respectively. Moreover, no significant relationships were observed between test duration, reaction time, and number of errors in Stroop tests 1 and 2 and the level of heat (P-value<0.0001). However, the mentioned variables had a significant positive correlation with Stroop test 3. Additionally, for exposed group variables of test duration, reaction time, and number of errors in Stroop 3 were significantly higher than those of control group.

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Conclusion: According to the findings in present study, heat stress causes an increase in reaction time and a decrease in selective attention. Thus, heat can be assumed as a stressor in hot work environments and the heat should be taken into account while design of job and tasks which needed selective attention or reaction time.

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Introduction: Polycyclic aromatic hydrocarbons (PAHs) are one of the most significant current environmental issues. Phenanthrene and naphthalene adsorption at activated carbon beds prevent the release of these compounds into the environment. The objective of this research was to compare the amounts of phenanthrene and naphthalene adsorption at activated carbon beds in the n-hexane solution.

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Material and Method: This discontinuous experimental study was conducted in the laboratory scale batch and in the n-hexane solution containing phenanthrene and naphthalene.PH values were adjusted by adding hydrochloric acidand 1 N NaOH. The initial and residual phenanthrene and naphthalene concentrations were spectrophotometrically measured at 270 and 266 nm, respectively.

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Results: Findings showed that the maximum adsorption of naphthalene was obtained at pH=5 and contact time of 8 hours (7.4 mg/gr). The maximum adsorption was reached at pH=7 and contact time of 11 hours for phenanthrene (8.34 mg/gr).Improvement in the adsorption capacity was happenedby the increases in contact time and initial phenanthrene and naphthalene concentrations. The adsorption kinetics of these two compounds followed pseudo-second-order and Freundlich isotherm model.

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Conclusion: Freundlich isotherm model showed a strong association with PAHs adsorption process. A weak correlationwas observed between Langmuir theory and the results of the adsorption at activated carbon beds in the organic n-hexane solution.

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Introduction: Emotional intelligence as the ability to understand and control feelings and emotions, and job satisfaction as positive attitudes of employees towards their jobs is amongst the effective indicators in the workplaces. Therefore, this research invetigated the effect of emotional intelligence of employees on their job satisfaction in one of the Oil refineries in Tehran.
 

Methods and Materials: This research is a practical and cross-sectional study. The statistical population consisted of 300 employees selected by stratified random sampling method. Bar-On questionnaire (90-item) and JDI questionnaire (70-item) were used in order to measure emotional intelligence and job satisfaction, respectively. LISREL8.72 software was employed to estimate causal effect between study variables and calculation of descriptive indices and comparison of variables were done by means of SPSS software version 18.
 

Results: According to results, there was a direct association between emotional intelligence of employees and their job satisfaction. In other words, the higher emotional intelligence, the higher rate of job satisfaction. Of the 15 sub-scales of emotional intelligence, Responsibility and Self-expression obtained the highest and the lowest scores, respectively. Furthermore, Supervisor and Salaries were ranked as the highest and the lowest valued subscales of job satisfaction. According to the results, employees job satisfaction level are improved in parallel to increase of education level and the maximum score of this variable was belonged to the age group of 30-45 years.}
 

Conclusion: Emotional intelligence, as a psychological variable, affects the worker's job satisfaction. Considering the direct relationship between these two variables, by training and increasing the emotional intelligence of employees, job satisfaction and consequently their efficiency and productivity can be improved in the workplaces.

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Introduction: Nowadays, exposure to extremely low frequency (ELF) magnetic field has been interested in many studies due to possible effects on human physical-mental health. Therefore, this study aimed to assess arc welders’ exposure to extremely low frequency magnetic field and to determine its relationship with the secretion of paratormone (PTH) hormone and mood states.

Material and Method: The present study has been conducted among 35 healthy production workers (as exposed group) and 35 healthy administrative personnel (as unexposed group). After checking the work activities of participants according to the guide recommended by the National Institute for Occupational Safety and Health (NIOSH), ELF magnetic fields were measured using an ELF measurement device in the regions including trunk, head, and neck. The plasma levels of PTH hormone of both groups were evaluated by the Electrochemiluminescence method. Stress-Arousal Checklist (SACL) was used to assess the mode states of subjects in both groups. The collected data were analyzed by SPSS software version 16.

Result: There was a significant difference between the exposed and unexposed groups with respect to the exposure level to ELF magnetic fields (P-value<0.0001). Mean PTH hormone level in exposed group (34.54 pg/ml) was lower than unexposed ones (37 pg/ml), however these mean values weren’t significantly different (P-value=0.67). Score of “stress” subscale related to the “pleasure” and score of “arousal” subscale  related to the “activities and alertness” in the unexposed group were significantly higher than those in exposed group (p<0.0001). Regarding the relationship between exposure level to ELF electromagnetic field and scores of  stress, arousal, and PTH hormone level in the two groups, it should be stated that only a significant and positive association was found between the average exposure to ELF magnetic fields and PTH levels in the exposed group (P-value<0.009, r=0.44).

Conclusion: The results of this study showed that continuous welding can be considered as an exposure source to extremely low frequency electromagnetic fields. More accurate and comprehensive laboratory and field studies are needed to prove the hypothesis of the potential impact of extremely low frequency magnetic fields on people’s psychological states and mood through changes of parathyroid hormone level.

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Introduction: Nowadays, Shielded Metal Arc Welding (SMAW) is the most widely used arc welding. During the welding operation, typically, various harmful agents such as fumes, gases, heat, sound and ultraviolet radiation are produced of which fume is the most important component from the viewpoint of occupational health. The present study aims to compare the number and the mass concentration emitted in SMAW to determine the most appropriate index of exposure to fumes in the welding processes.

Material and Method: In this study, the portable laser aerosol spectrometer and dust monitor of GRIMM, model 1.106, was used to measure the number and mass concentration of fumes emitted from SMAW on 304 stainless steel with a thickness of 0.4 mm. Air sampling was performed at a distance of 41 cm representing the welder’s breathing zone. The measurements of number concentration (NC) and mass concentration (MC) were taken under the condition of 25 volt voltage and direct current of the electrode polarity.

Result: The total NC and MC of welding fumes in welder’s breathing zone was 1140451 particles per liter and 1631.11 micrograms per cubic meter, respectively. The highest number concentration was found to correspond to the particles with 0.35 to 0.5 micrometer-sized distribution (NC1; 938976 particles per liter) and the lowest was related to the particles with 5 to 6.5 micrometer-sized distribution (NC7; 288 particles per liter) and the particles larger than 6.5 micrometer (NC8; 463 particles per liter). Moreover, the highest mass concentration was related to the particles with 0.35 to 0.5 micrometer-sized distribution (MC1; 450 micrograms per cubic meter) and the particles larger than 6.5 micrometer (MC8; 355 micrograms per cubic meter).

Conclusion: The findings indicated that there is no agreement between number and mass concentration as two particles assessment index, and as the particles’ size become smaller, the mismatch of them is becoming more apparent. Since the smaller particles penetrate into the lower respiratory tract and have higher potential for adverse health effects, it is necessary to measure and assess particles in various size distributions and especially the smaller fraction of particles. Therefore, it is thought that considering the mass concentration alone and not paying attention to number concentration in the assessment of exposure to particles in the industrial workplaces and specifically in welding stations will not be reflected valid assessment of adverse health effects of welding fumes as a systemic poison on body organs.

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Introduction: Heat stress is one of the harmful risks in casting and die casting industries, which can not only cause work-related diseases but also can impair the performance and safety of workers. Since the indicators that are used to evaluate heat stress are very different, it is very difficult to choose a suitable index. The aim of this study was to determine the optimum heat stress index in foundry, die-cast, and road construction industries using FAHP and Topsis methods.

Material and Method: In order to determine optimum heat stress index in foundry, die-cast, and road construction industries, first, the prioritization criteria were defined by experts (including ease of measurement, measurement accuracy, comprehensiveness, time, cost, and correlation). Then, considering these criteria, the best heat stress index was determined based on experts’ opinions and using FAHP and Topsis methods.

Result: The results of this study suggest that given the current conditions and criteria, WBGT and P4SR is the best indices for foundry, die casting and construction.

Conclusion: The results showed that according to comprehensiveness, accuracy and correlation criteria, the WBGT index is considered as the best indicator of heat stress assessment in foundry, die-cast and road construction industries. Moreover, the HSI ranked in the last place due to the complexity and cost of its calculation.

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Introduction: A high percentage of musculoskeletal disorders in workplaces occur due to awkward posture and non-ergonomic design of the work stations for lifting and carrying of materials. To avoid these injuries, jobs should be designed in a way that ergonomics risk factors are controlled properly. The aim of this study was to utilize ergonomics interventions to minimize ergonomics risk factors in bag packing unit in a mineral processing plant.

Material and Method: This cross sectional study was carried out among 20 workers of bag packing unit. Camera recording of working postures, evaluation of medical records, interview, and REBA technique were used to identify the ergonomic risk factors. Interventions included changing the conveyor belt height and the use of spring pallets (spring table). Data were analyzed using Paired T-Test by SPSS software version 18.

Result: Before implementing ergonomics intervention, a total of 75% of evaluated postures by REBA technique obtained score of 8-10 (very high risk level) and 25% had score of 11-15 (very high risk level) that correspond to the action level 3 and 4, respectively. Following the implementation of ergonomics interventions, a total of 90% of the analyzed postures showed action level 2 (moderate risk level) and the remainder 10 percent of evaluated postures showed high risk level. Comparison of REBA technique scores before and after implementing interventions showed a significant difference (P-value < 0.05).

Conclusion: Based on the findings of this study, the implementation of ergonomics interventions has remarkably decreased the required action level and it may be able to improve work-related postures.

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Introduction: Exposure to crystalline silica dust can seriously threaten health of workers engaged in processes such as casting, stone crushing, grinding, construction activities, insulator manufacturing, and glassblowing and sandblasting. The aim of this study was to assess occupational exposure to crystalline silica and to determine the risk of mortality from silicosis and lung cancer in an insulator manufacturer.

Material and Method: Air personal sampling was performed using 10 mm nylon cyclone and mixed cellulose ester (MCE) membrane filters (5 mm diameter, 0.8 μm pore size) for 60 male workers. Samples were prepared and analyzed according to the National Institute for Occupational Safety and Health (NIOSH) 7601 standard method. The risk assessment of mortality due to silicosis resulting from crystalline silica exposure was done by using model of Mannetje et al. for the period of 10 years. The mortality rate of lung cancer was determined using a linear regression model derived from the study Rice et al.  

Result: The highest and lowest exposure levels to silica were belonged to the packing unit (0.54±0.28 mg/m3) and the furnace (0.02±0.01 mg/m3), respectively. Crystalline silica concentrations for all samples were higher than Threshold Limit Values (0.025 mg/m3) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). According to Mannetje et al. model, the cumulative exposure of 25% workers was in the range 0 to 0.99 that it represents 1 death per 1,000 people. The risk of mortality due to lung cancer was obtained in the range of 7-94 persons per 1000 workers exposed to silica.

Conclusion: In general, the geometric and arithmetic mean of crystalline silica exposure was higher than threshold limit value for most of the subjects. For all workers of the insulator manufacturer, the risk of silicosis related mortality was higher than 1/1,000 (unacceptable level of risk). Predicting the lung cancer mortality from silica exposure indicated a high level of mortality risk among understudied workers.

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Introduction: Heat stress is one of the Hazardous physical agents in the workplace, which can cause impairment of cognitive performance. The current study aimed to evaluate the effect of different levels of heat stress on attention and reaction time in a laboratory condition.

Material and Method: This experimental study was done among 33 students included 17 males and 16 females. Mean age of the participants was 22.1(SD=2.3). Attention and reaction time parameters were evaluated using the continuous performance test and  reaction time measurement device respectivlely, after exposure to different heat levels (22°C and 37°C). Data were analyzed using ANOVA test and SPSS 20 software.  

Result: The results of tests attention and reaction time showed that the average of attention percentage was decreased and the average of reaction time increased by increasing the heat level, with a  statistical differences of  (P˂0.001) in both cases. Attention percent in terms of exposure to 22°C temperature was significantly higher than 37°C (P˂0.001). But, reaction time was significantly higher than with the exposure to 37°C temperature than 22°C (P˂0.001).

Conclusion: The results of this study showed that, heat by increasing reaction time and decreasing attention leading to an impairment  in the individual’s cognitive performances. Therefore, in jobs such as control rooms and various industries that need attention, concentration and quick reaction, it is necessary to consider and optimize the heat conditions in order to increase the level of attention and decrease of reaction time.

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Introduction: Despite the ongoing efforts to reduce human errors in various systems, errors and unsafe behavior are the main cause of accidents in the workplace. Many studies have been conducted to identify and improve human error in recent years. The number of studies about the human error with the variety of topics has made it an overall overview difficult for researchers. Therefore, a systematic review of previous studies can be the best way to share useful findings and make a trend for the future research in the field of human error.

Material and Method: After a systematic search of valid databases, the analysis was focused on the title, publication year, journal title / Congress, city/region, the level of organization, job search, type of organization and the methods used. And articles were evaluated based encryption.

Result: Three groups of human error studies were identified. The first group studies in safety management, safety assessment, and safety planning have investigated the human error. The second group has examined the influence of individual characteristics such as behavior, cognition, and education on human error. The third group has focused on data arise from the previous accident to improve behavior and reduce human error. To make a better orientation for next studies two essential aspects included chronological analysis and thematic analysis was considered.

Conclusion: This study made an attempt to identify the gaps in the studies related to human error and afford some appropriate strategies.

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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: Heat stress is one of the hazardous agents in the steel industries which can threaten the health and safety of workers and lead to serious occupational diseases. The aim of the study was to assess the heat stress in the steel industries and compare PHS (Physiological Strain Index), WBGT (Wet-Bulb Globe Temperature), DI (Discomfort Index) and HSI (Heat Stress Index) indices for the estimation of heat stress and to determine the optimum index for steel industries.
 

Material and Method: This descriptive-analytic study was conducted among 220 workers engaged in two steel industries in Iran. Environmental and physiological parameters were measured according to ISO 7726 and ISO 9886 in three times of measurement, and finally the time-weight average of the heat stress indices were calculated. All data were analyzed using SPSS ver.  20.
 

Result: The time-weight average of WBGT (28.28 oC), DI (29.11 oC), HIS (65.7 %) indices were higher than the recommended limits. Physiological parameters (oral, tympanic and skin temperatures, systolic and diastolic pressures and heart rate) had the greatest value in the second time of measurement (afternoon). WBGT index comparing to the PHS, DI and HSI indices had highest correlation with oral, tympanic and skin temperatures and heartbeat (r=0.314 , 0.408 , 0.459 , 0.302, respectively; P < 0.05), while systolic and diastolic blood pressures showed no significant correlation with WBGT (P > 0.05). The WBGT index had the highest correlation with studied indices which was 0.945, 0.681 and 0.600 for DI, PHS and HSI, respectively.
 

Conclusion: This study assessed the optimal index with regard to the physiological parameters, and it was concluded that the WBGT index has the highest correlation with the most of physiological parameters, and therefore, WBGT index can be the most optimum index to heat stress assessment   in the studied steal industries.

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Introduction: Being aware of the explosion, fire radius, and their damages, has an important role in accident prevention methods. Therefore, the aim of this study was modeling and evaluation of the consequences of propylene oxide spill in a petrochemical company.
 

Material and Method: The QRA method including seven steps was used in this study. In the present study, in order to examine and modeling of the propagation propylene oxide, first a familiarization with the process information of the unit was done then, a risk assessment was carried out adopting HAZOP technique to identify existing hazards. Consequence analysis in a process unit includes: selecting important scenarios, characterizing scenario, modeling the consequences of scenarios, analyzing the results and determining the percentage of mortality. PHAST software version 6.51 was used for modeling of outcomes and assessment propylene leak.
 

Result: urves of the firing zones of sudden release of propylene oxide showed that the influence puts are included up to radius of 0.15 meters in the scenario of leakage 5 mm, in scenarios with leaks 25 mm to a radius of 1.1 meters and in scenarios with leakage of 100 mm to a radius of 39 meters. The maximum intensity of flash fire in the initial point Scenario 5 mm was 4.2 kW/m2, in the scenario of radiation leakage was 25 mm at the distance to 5 meters from the fire intensity up to maximum of 9 kW/m2, and also in the scenario with 100 mm flash fire radiation leak at an earlier point fire was 14 kW/m2. The maximum intensity of thermal radiation at the distance to 5 meters up to 16.5 kW/m2, and maximum distance of 80 meters around the reservoir affected. The mortality rate of flash fire has exposed employees, was 50 percent.
 

Conclusion: Many accidents caused by leakage and explosion were due to corrosion, spoil tanks and equipment, and the majority of such accidents can be prevented by technical inspections and continuous audits.

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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: Workers in steel manufacturing companies are extensively exposed to the volatile organic compounds (VOCs). Considering the health effects of these compounds, the purpose of this study was to determine occupational exposure to the BTEX compounds and also evaluation of carcinogenic risk due to benzene and non- carcinogenic risk for BTEX compounds in a steel industry.

Material and Method: This cross-sectional study was conducted in the coke production unit of the steel making industry. After collecting personal samples from breathing zone of the workers and analyzing of the samples the levels of exposure to the BTEX were quantitatively determined using Gas chromatography equipped with Flame Ionization Detector (GC-FID), according to the NIOSH 1501 standard method. Then, cancer risk due to benzene and non-cancer risks from BTEX compounds were calculated using Monte-Carlo technique.

Result: The analysis of personal samples indicated that benzene concentration in energy and biochemistry and benzol refinement sections of the plant were higher than occupational exposure limits (OELs). Among the studied sections, benzol refinement as the most polluted section had the highest concentration of BTEX compounds. Non-cancer risk due to BTEX compounds in all studied sections was lower than one. Benzene cancer risk in energy and biochemistry, benzol refinement and experimental furnace sections was higher than maximum recommended value by EPA.

Conclusion: Due to the high concentration of benzene in energy and biochemistry and benzene refinement sections as well as the resultant carcinogenic risk, improvement of existing control systems and the use of modern engineering systems are necessary to control occupational exposure.

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Introduction: Nowadays, millions of people are exposed to the dusts in their workplaces. Occupational exposure to dusts is considered as one of the most common and serious occupational hazards to workers’ health. The purpose of this literature review was to review the literature related to the occupational exposure to dusts in Iran published over the past 14 years.  
Material and Methods: In this review, published articles were obtained from Web of Science, PubMed, Google Scholar, Scopus, ScienceDirect, Islamic World Sciences Citation (ISC), Magiran, SID، Iran Medex, and Civilica search engine. The main keywords for search were Occupational Exposure, Lung, Dust, Total Dust, and Respirable Dust. The relevant articles published in Iran over the past 14 years were searched and extracted after checking their relevancy. All articles were classified based on the titles, years of publication, places of publication, type of industries, geographic distributions, sampling and analysis methods, fields of study, and the amounts of exposure.
Results: Findings showed that in spite of increases in the rate of published literature in recent years and by considering geographical variation and the large number of dust generating firms and industries, a relatively small number of studies was conducted and published in this field. Majority of the studies in this field considered the levels of dust exposure and respiratory effects of dust exposures.  In most studies the levels of occupational exposure to dusts (and crystalline silica dusts) were higher than the recommended limit values.
Conclusion: Although an increasing number of studies can be seen in recent years on occupational exposure to dusts and their effect, by considering the presence of large and small size industries with dust generating pollution  in Iran, the large number of exposed people, adverse-health  effects,  and  the need for control measures, few studies have been published in this field and further works need to be done in this area.

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Introduction: Exposure to organic solvents cause adverse effects on various systems such as the central nervous system, behavioral and cognitive changes, sleep disorders, as well as changes in mood. This study was aimed to evaluate the effect of long term exposure to mixed organic solvents on positive and negative aspects of the mood of the workers of a painting industry.  
Material and Methods: In this cross-sectional study, based on the obtained results of Gas chromatography–mass spectrometry (GC-MS) analysis and neuro-behavioral effects of benzene, toluene, ethylbenzene and xylene (BTEX) compounds, these compounds were selected as the main organic solvents for the study and the amount of these compounds was quantitatively determined according to the National Institute for Occupational Safety and Health (NIOSH) 1501. Furthermore, the mood status of workers was evaluated by the validated Persian version of BRUMS (The Brunel Mood Scale) questionnaire and the obtained data were analyzed using SPSS software, version 24.
Results: The mean of exposure to mixed organic solvents in different sections of the exposed group was reported to be 0, 0.27, 0.76, and 2.6 ppm. By increasing exposure to mixed organic solvents from the first quartile to the fourth quartile, fatigue and calmness scores were increased with a strong correlation (r = 0.7). Also the fatigue and calmness scores in the groups having elevated exposure were significantly higher than the control group. Furthermore, the obtained scores for tension, depression and anger in the exposed group were significantly higher than control group (p- value <0.05). There was no significant relationship between demographic data such as age, work experience and smoking with different subscale of mood status.
Conclusion: Long term exposure to low level of BTEX compounds has made an adverse effect on positive and negative mood status in different aspects. Also, increasing the level of exposure to mixed organic solvents was positively correlated to the obtained scores for fatigue and calmness.