Journal of Health and Safety at Work

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: Musculoskeletal disorders are the most prevalent problem in the workplace. Unsafe manual material handling is amongst important causes of such disorders. Unsafe manual material handling can result in different musculoskeletal disorders such as acute physical injuries and increase of strain in back, shoulders and arms. United state society of orthopedic surgeons ranked back pain as the most costly disorder, which workplaces are considered to be responsible for most of them. Few studies compare related national and non-national standards in Iran. Therefore, the aim of the present study was to compare Iranian manual material handling regulation, NIOSH equation and MAC method in one of metal casting industries in Tehran, 2001.

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Material and Method: In this cross-sectional study, participants were randomly selected among men workers, working in industry. Data collection was done using MAC data sheet, NIOSH equation and Iranian MMH regulation. Data were Analyzed using stata software and P-value of 0.05 or less was considered significant.

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Result: Results showed an acceptable agreement between Iranian regulation and MAC method as well as Iranian regulation and NIOSH equation. However, no acceptable agreement was observed between MAC method and NIOSH equation.

Introduction: previous studies have shown approximately 90% of accidents in the workplace are due to unsafe behavior and human errors. Identifying predictors of unsafe behaviors would be unsafe in accidents prevention. The purpose of this study was to investigate personality characteristics, cognitive and organizational variables of line workers in an industrial company in bojnurd.

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Material and Method: The sample, in the main stage, consisted of 300 employees and in the validation stage 100 They were selected thought stratified random sampling. Firstly, participants were divided into two groups (safe and unsafe) using safety behavior scale. Next, each group was evaluated using the five-factor personality questionnaire, safety efficiency questionnaire, regulatory focus at work, safety climate, safety motivation and safety competency scales and also perceived work pressure questionnaire. In order to analyze the data, the discriminate analysis, the confirmatory factor analysis and the Pearson’s correlation coefficient were applied.

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Result: According to the result of the present study, unsafe behaviors of employees can be predicted by neuroticism, extroversion, agreeableness, consciousness, safety efficiency, regulatory focus and its dimensions, safety climate and its dimensions, safety motivation, safety competency and role overload variables.

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Conclusion: The results of this study showed the importance of safety competency, prevention focus, safety rules and procedures, safety efficiency and consciousness as predictors of unsafe work behaviors. Therefore, it is recommended to rely on these variables in the safety training courses and also in selecting people for high risk environments.

Introduction: In developing countries, promotion of road safety is of crucial importance. This paper presents the status of road safety in Iran during 2001 - 2006.

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Material and Method: The status of road safety in Iran was surveyed in this descriptive study using road safety indicators a in macro level. Firstly, 46 indicators were identified after studying almost all indicators related to the road safety. After consulting of views with road safety experts and considering the reliable existing data, 11 indicators were selected to study the safety status of the roads. Then, all essential data for determining each indicators were collected from related organizations and institutes. All indicators were determined and evaluated in the last step.

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Result: The results revealed that during the period of 6 years, death toll has been increased by 9 deaths per 100000 person of the population. Moreover, application of seat belt and safety helmet has been increased by 20% and 18%, respectively. It also indicated that the number of motorists and the length of paved roads have been increased by 20%, and 10%, respectively. The net income per capita has also grown from 5884 US$ to 7968 US$ and the life expectancy has gone up from 68.9 years to 70.9 years, the percentage of the literate population has grown by 2% (from 76% to 78%) and the human development index has increased from 0.721 to 0.759. The results of the present study showed that the increased level of death toll per 10000 vehicles and the increased level (%) of seat belt as well as helmet application, paved roads, urbanization, the net income per capita, life expectancy, literacy and human development index were statistically significant and R2 coefficient for this factors was 0.84, 0.9, 0.994, 0.9, 0.97, 0.82, 0.69 and 0.84 respectively.

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Conclusion: According to result of the present study, roads safety were not in an appropriate level. The roads safety status can be determined using road safety indicators to be applied for road safety promotion.

Introduction: Due to the presence of extreme hazard sources and high intrinsic risk in refineries and process industry sectors, different layers of protection are being used to reduce the risk and avoid the hazardous events. Determining Safety Integrity Levels (SILs) in Safety Instrumented Systems (SISs) helps to ensure the safety of the whole process. Risk Graph is one of the most popular and cost effective techniques to do so. Despite Risk Graph simplicity it’s a qualitative method which is highly subjective and suffers from interpretation problems that can lead to inconsistent or conservative SILs.

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Material and Method: In this paper, Improved Risk Graph (IRG) method was presented and evaluated, and using Fuzzy Logic a novel approach namely Fuzzy Improved Risk Graph (FIRG) was suggested. In the proposed method consequence levels which were defined as qualitative terms were transformed into quantitative intervals. Having those numerical values, risk graph table was converted to a quantitative one. Finally, applying the presented approach and using three experts’ opinions and attributing weight factors, an ultimate numeric value was produced.

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Conclusion: as a result of establishing the presented method, identical levels in conventional risk graph table are replaced with different sublevels that not only increases the accuracy in determining the SIL, but also elucidates the effective factor in improving the safety level and consequently saves time and cost significantly. The proposed technique has been employed to develop the SIL of Tehran Refinery ISOMAX Center. IRG and FIRG results have been compared to clarify the efficacy and importance of the proposed method

Introduction: Researches show that workplace quality play important role in developing job involvement. The purpose of this study was to determine the predicted power of job involvement by perceived supervisor support and perceived coworker support.

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Material and Method: This research was a cross-sectional study. The participants consisted of 189 employees from Isfahan Steel Company in 2012 and they were selected according to the stratified random sampling method and responded questionnaires about demographic characteristics, perceived supervisor support, perceived coworker support and job involvement. Data was analyzed using Pearson correlation coefficient and regression analysis.

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Result: The results showed that there were significant relationships between perceived supervisor support and perceived coworker support with job involvement (p<0.05). Also, results indicated that the variables of perceived supervisor support and perceived coworker support significantly predicted almost 13% and 11% of job involvement variance (p<0.05).

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Conclusion: The research results maintain the importance of psycho-social variables in predicting job involvement in workers.

Introduction: Although risk assessment and accident prevention program have been widely used in industries such as steel industry, there are still numerous accidents in these industries. Hence, applying an accident analysis method can identify the root causes and casual factors of accidents and causal factors. Human Factors Analysis and Classification System can identify human errors in the steel industry by using an analysis of past events. The aim of this study was to identify the human errors in the steel industry using the HFACS methodology.

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Material and Method: In this study first, incident reports of industries with high risk, such as Ahvaz steel and pipe industries existing in the department of work and social security was gathered. Then, an analysis of accident was done based on HFACS model. This model has 4 levels and 18 categories which are 1 - unsafe acts of operators (that includes four subtypes) 2 - pre-conditions for unsafe acts (with seven categories) 3 - unsafe supervision (includes four categories) and 4 - the effect of association (with three categories).

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Result: In this study, 158 reports of accident in Ahvaz steel industry were analyzed by HFACS technique. This analysis showed that most of the human errors were: in the first level was related to the skill-based errors, in the second to the physical environment, in the third level to the inadequate supervision and in the fourth level to the management of resources.

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Conclusion: Studying and analyzing of past events using the HFACS technique can identify the major and root causes of accidents and can be effective on prevent repetitions of such mishaps. Also, it can be used as a basis for developing strategies to prevent future events in steel industries.

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: currently, stress is known as one the most important issue among societies which may have positive or negative results. Stress is caused when there is not a harmony between job demands, capabilities and desires of a person. Most of the behavioral, physical and mental disorders are results of job stress. The objective of this study was Validity and Reliability analysis of NIOSH Generic Job Stress Questionnaire (GJSQ), in order to have an appropriate tool for evaluation and analysis of job stress in Iran.

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Material and Method: In this study, 228 members of Tehran fire-fighting office were chosen according to categorical and clustering sampling, methodology and they completed NIOSH Generic Job Stress Questionnaire (GJSQ). For Validity and Reliability of questionnaire, 20 persons of the group were chosen for content validity analysis of the questionnaire. For Reliability analysis of the result, Cronbach alpha test and in-cluster correlation test were used. SPSS software version 18 was used for analysis of the data.

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Result: The mean age of the participants was 30.8 years (SD=4.9) and the average of job tenure in fire-fighting office was 7.4 years (SD=4.8). In order to reliability analyze the questionnaire, Cronbach alpha coefficient of all influential factors was obtained more than 0.7. In-cluster correlation coefficient of the questionnaire is calculated using retesting on all influential factors. With the exception of Physical Environment and Mental Demands which were about average, all other coefficients were over 0.7, which is a very appropriate result.

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Conclusion: Considering that Validity and Reliability factors of the questionnaire were be appropriate, it can be recommended that NIOSH Generic Job Stress Questionnaire (GJSQ) can be used as a Valid and Reliable questionnaire for job stress evaluation in Iran.

Introduction: Pollutants in gas turbine air intake can cause erosion ،corrosion، fouling as well as reduction of power and efficiency of turbine and noticeable economic losses. In order to select the appropriate filtration system, air monitoring of turbine inlet and its filtration is essential. Therefore, this study was performed to assess the quality of gas turbines inlets in a gas power plant in Tehran.

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Material and Method: In this cross- sectional study, the concentration of particulates contained in air intake of 4 types of gas turbines, including: Fiat, Assec, Hitachi and mitsubishi were evaluated in second-half of spring season. For this means, 12 series of air samples were collected using 8 stages cascade Impactor, model AN -200 made by OGAWA company on cellulose – ester filters . The dust concentrations were determined gravimetrically in different ranges of sizes . Then the concentrations of 8 metals including Sodium, Potassiumu Lead, Mercury, Aluminum ,Copper and Cadmium were measured using ,Atomic Absorption Spectroscopy method and the data were statistically analyzed by SPSS Software, version16.

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Results: The results showed that the mean of particulate concentration with the diameter less than 4.7 µ were 64% ,66% ,60% ,67% for Fiat, Assec, Hitachi, mitsubishi respectively and it was 64.25% totally. The concentrations of all assessed metals in particulates less than 4.7 µ were greater than of larger than 5 µ. There were not any differences between particulate concentration in the inlet of Fiat and Hitachi (P>0.05), while in the case of other gas turbine intakes , there were statistically significant differences (P<0.05).

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Conclusion: Based on mass distribution of particles, the highest concentration belongs to particles with diameter of less than 4.7 µ. These particles could damage turbine blades, especially due to the presence of sodium and potassium as corrosive elements in this range (200 µg/m3). Therefore,this range of particle size must be considered in selecting the air intake filtration system.

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.

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: Possible contamination in nuclear medicine centers, in addition to health problems, affect the tests and much effort and cost is required for decontamination. Given the effects of ionizing radiation on human health, rules and regulations have been enacted to avoid contamination, that in working with radioactive materials should be followed to minimize them.

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Material and Method: After mapping of nuclear medicine centers in the province, areas that should be studied for measuring the amount of radioactive contamination were determined. The site selection for the tests were based on the area in which the possibility of further contamination were existance. After measuring the background count rate the radioactive contamination in studied areas were performed using Wipe Test.

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Result: The mean level of background contamination in centers 1, 2 and 3 were 1.75±0.150 μCi, 4.43±0.615 μCi and 2.47±0.055 μCi, respectively. In center 1, only region of Hood pollution was much higher than the permissible limit. In center 2, radioactive contamination of the waiting room, patient rooms, warehouse radiotracer, control room, hood, desk and floor center was exceeded. Also, in center 3, contamination of the doorway, hallway patients, control room, hood, desk, sink, cabinets, room and floor imaging injection (control), respectively, were higher than the permissible limits.

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Conclusion: In centers 1 and 2, most of the radioactive contamination occurred under the hood due to labeling of radiopharmaceuticals activity. Also, in center 3, the highest contamination rate belonged to patients’ corridor that could be due to frequent the area. According to this subject, necessary measures in this regard should be considered by the department responsible for health physics.

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: Heat stress in workplaces cause multiple problems such as thermal stresses, thermal discomfort and in more severe cases may lead to accidents and diseases related to excessive heat. The aim of this study was to evaluate heat stress adopting WBGT Index in some small enterprise in Qom city and also to examine the relationship between WBGT and physiological indices.

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Material and Method: This Cross-sectional study was conducted in 25 small workshops in Qom city including of 10 indoor and 15 outdoor workshops in August 2012. WBGT were measured according to the ISO7243 standard. The physiological responses including pulse rate, systolic and diastolic blood pressure were measured among 25 workers (one from each workshop).

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Result: The average WBGT index for indoor job were 27.55 Ċ among auto body repair, 27.45 Ċ in mechanics, 24.64 Ċ in painters, 26.73Ċ in welder and 25.89 Ċ in manufacturing doors and windows makers. For outdoor jobs as auto body repair, mechanics and painters it was 30.01 Ċ, and for welders and doors and windows makers 28.52 Ċ. Compared to the standard of ISO7243 WBGT all small workshops were higher than threshold limit. Auto body repair (30.22 Ċ) and painting (30.03 Ċ) workshops had highest WBGT. Average WBGT in auto body repair (as a job with most exposed to the open space and solar radiation) with welder and doors and windows, showed statistically significant differences T-test using WBGT with pulse rate, systolic and diastolic blood pressure did not have statistically significant (P>0.05). The findings indicated that workers are exposing to heat stress and doing more researches and representing preventive counter measures for the workers in this field are essential.

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Conclusion: Heat stress in almost all of the studied workplaces are higher than the recommended limits, and the outdoor workshops had the highest thermal stress, although heat stress did not show a significant correlation with the studied strains.

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: One of the most important threats for employees working in chemical industries is exposing to the chemical materials. Lack of precaution and control regulations during working with chemicals can have irreparable consequences. So, in order to achieve an effective control program, it is necessary to have an appropriate assessment of the procedures involving exposure to the chemicals. William-fine method can provide an acceptable insight into hazard risk rate.

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Material and Method: In this study, a combination of AHP and William-fine adopted to achieve a model for chemicals exposure risk assessment in oil and gas industry. The numbers were extracted from questionnaire, and then, they weighted entered to assessment the model. Finally, they were presented quantitatively with protection layer.

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Result and Conclusion: The results revealed that the quantitative amount of consequence, probability and exposure was 83.2, 8.45, and 2.2, respectively. Generally, the chemical exposure risk number was 1546 which shows that reforming plans are in highly priorities from an economical point of view. William-fine method has the benefit of an accurate chemical exposure by combination of effect severity, exposure probability and detriment rate, and also minimization of personal judgments during the assessment.

Introduction: Manual dexterity impairment due to wearing latex and nitrile gloves among health care employees and laboratory personnel can be a remarkable problem because of its adverse outcomes. The present study was conducted to “compare the effect of using latex and nitrile laboratory gloves on hand dexterity”.

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Material and Method: In a semi experimental study design, 30 university were students randomly selected from Urmia University of medical sciences. Subjects assigned in three experimental conditions, such as the control condition (without gloves), with latex glove and with nitrile gloves. Then, dexterity level of fine finger and gross of the subjects were calculated using the Purdue pegboard test. Repeated measures one-way ANOVA test and T-test and Pearson’s correlation coefficient were used for statistical analysis.

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Results: The result showed that the differences between three groups of laboratory conditions from the level of gross and fine finger dexterity were statistically significant (p‹0.05). As the latex gloves showed significant and positive effect on gross and fine finger dexterity comparable with nitrile gloves and control group but there was no significant difference between the gross and fine finger dexterity of nitrile gloves when comparing with the control group. In other words, the nitrile gloves had not negative effect on gross and fine finger dexterity.

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Conclusion: Considering that there was no significant difference in the score of both fine finger and gross hand dexterity while using nitrile gloves as compared to the control condition (without gloves), means that use of nitrile gloves has no adverse effect on hand dexterity therefore, using nitrile gloves is recommended as a alternative for the latex gloves, considering the additional advantage of no allergic reaction in this gloves.

Introduction: PAHs are organic compounds with benzenic rings that releas from hot asphalt as incomplete combusting. These compounds are one of the major concern in scientific societies, workplace and environment due to their stability, bioaccumulation, carcinogenic and mutagenic effects. Since asphalt workers are exposed to PAHs frequently in their job, in this study it was attempted to evaluate respiratory exposure of asphalt workers to PAHs in their breathing zone.

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Material and Method: In this study air samples of the asphalt workers were collected in accordance with the NIOSH 5506 method using PTFE filter and XAD-2 adsorbent. The ultrasonic bath and acetonithrile are used in order to extract the analytes from the filter and adsorbent. Also, the samples were analyzed by HPLC-UV.

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Result: In all samples, Finisher assistance and oilman with 1754.48 ng/m3 , 24.65 ng/m3 had maximum and minimum exposed to ∑PAH, respectively. Among the PAHs compounds, which asphalt workers exposed to, Naphtalene had the highest concentration. Among different asphalt workers tasks, screedman expoused to PAHs, had a significant difference.

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Conclusion: Evaluation of Polycyclic aromatic hydrocarbons concentrations in the breathing zone of asphalt workers indicated that exposure to these compounds were below the occupational exposure limits recommended by NIOSH, OSAH, ACGIH and Iranian OEL. Due to the highly carcinogenic potential of some of these compounds and absence of occupational exposure limits for these compounds, likes Chrysene and Benzo (a) Anthracene, it is strictly recommended to employ engineering controls and using suitable PPEs. This study also indicated that the exposure to PAHs in the most asphalt workers tasks had significant differences, and it can be due to proximity of the workers to the source of hot asphalt and also exposure to the exhaust gases that releasesd from the construction machinery.

Introduction: Bioaeroslos released from wastewater treatment plants may contain pathogens existing in the sewage which could endanger the health of workers. The aim of this study was to evaluate the status of bioaerosol emissions form in a sanitary wastewater treatment plant.

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Material and Method: This cross-sectional study was carried out in different units of a sanitary wastewater treatment plant. For this purpose, air samples were collected on blood agar and dextro agar in an Andersen single-stage sampler with flow of 28.3 lit/min for 10 minutes. Collected samples were shipped to the lab immediately and incubated for 48 hours. Then, incubated samples were counted for colonies concentration.

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Result: Based on the result of this study, the mean density of bacterial and fungal bioaerosols in all wastewater treatment plants were 412.86±23.30 and 53.72±23.99 CFU/m³, respectively. Microbial contamination of the air within a kilometer away from the site (control areas) was 17 times less than its average density.

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Conclusion: Wastewater treatment processes can contaminate the air surrounding the plant, particularly with bacteria bioaerosols. Therefore, it is necessary to control the emissions and protect the health of workers against risks arising from exposure to bioaerosols.