دو ماهنامه سلامت کار ایران
سال دهم شماره 2 (خرداد و تیر 1392)

With the increasing application of nanotechnology concerns about the negative effects of human exposure and environmental releases of these particles is also doubled. Among the most well-known media، ULPA filters are used to control nanoparticles. In this study، the efficiency and pressure drop of ULPA fiber bed for collection and removal of nanoparticles were investigated. ULPA filter efficiency and pressure drop was measured by using nano-scale aerosol particle size range 70 -700 nm sucrose at different flow rates 1. 58 - 5 cm. s -1. The ULPA filter used had a thickness of 0. 4 mm. A cylindrical test system was constructed as a form of stainless steel with a filtration surface of 0. 013m2. Desired particles were generated using Electrospray 3480 model particle generator. Condensation particle counter CPC Models 5. 410 Gream Company was implemented to measure particle number concentration before and after filter bed and to calculate the performance. Results showed that the maximum amount of substrate permeability of ULPA media (independent of the velocity rate) was for the particles of 100 nm and it was determined as the MPPS in this media. However، data analysis revealed a significant relationship between diameter and efficiency parameters of the MPPS (negative)، and the MPPS (positive). The ULPA media used in this study with the MPPS particles of 100 nm can be introduced as a particles control substrate for experimental conditions presented in the study

Considering the role of human errors in the incidence of catastrophic events in control rooms and also Lack of effectiveness of classical techniques to identify the human errors، special techniques are required for identification of human errors. Therefore، this study aimed to identify human errors in the control room in an oil company Using HEIST Technique. The present study is a case study of qualitative research that was conducted with using HEIST Technique. Collection of the required information has been done with Walking-Talking Trough and «Rose & Roses» model that is used for classification the decision-making process. «Kirwan» model is used for classification of factors that are involved in human errors and Types of errors have been detected with the SRK Model. Overall، 300 human errors has been detected. Of which،» interactions with controllers and indicators «،» instructions «and» training and experience «alone causes 71 percent of human errors in control room operators. In addition، 90% of human errors were related to the «stages of implementation of the solution»، «observing system» and «selection hypothesis». The results of this study showed a variety of possible scenarios resulting from human errors and their unintended consequences. These results emphasize that there are several weaknesses suggesting the implementation of both engineering and administrative controls simultaneously to reduce human errors

Halogeneated hydrocarbons are among the most important classes of toxic chemicals considering environmental and occupational health which can be quantified by several methods. This study examined the applicability of solid phase microextraction for sampling and quantifying of 2-Chlorophenol in the air. A dynamic standard atmosphere generation system was constructed and effects of sampling parameters such as fiber type، calibration mode and retraction length on sampler performance were studied. Actual sampling rate calculated according to side-by-side sampling was used for quantifications. The effects of environmental parameters including temperature، humidity، and air velocity، were studied. There was no significant difference among sampling rates at different temperatures and velocities (in dynamic conditions) but relative humidity had a significant negative effect on the sampling rate. Storage ability of the SPME samples were seriously depends on the time and temperature of storage. The SPME samples had a poor storage capacity in comparison with the charcoal samples. However، sample recovery increased with decreasing the storage temperature. CAR/PDMS SPME in retracted mode is a good alternative for sampling and analysis of this class of compounds in the air. Its sampling rate is stable in wide range of temperatures and velocities. Therefore، it can be used readily in environmental and occupational exposure assessments.

Magnetic resonance imaging as one of the best medical scanning technique is considered to be the most important sources of static magnetic fields. The staffs of MRI ´s units frequently exposed to these static magnetic fields. This study aims to determine the occupational exposure level to mentioned field and its related health effects in MRI´s units. The occupational exposure level of 20 staffs in the four MRI ´s units in the Shiraz city was measured using personal monitoring instrument model HI 3550 based on IEEE C95. 3. 1 method. A questionnaire related to health effects of magnetic fields was distributed and completed between 25 staffs of MRI ´s units and 30 nurses employed in typical hospital as a control group. Finally، the obtained data was analyzed by spss19 software. The result showed that the time weighted average of the staffs exposure was 48. 6±2 mT/8 hours in relation to 1. 5 T MRI systems. Therefore، occupational exposure of staffs was lower than Iran national exposure limits (60mT/8 hours). In addition، magnetic field strength decreased with increasing the distance from MRI system. In addition، the frequency of health effects related to magnetic fields such as anxiety، sleep and concentration disorders and tiredness between case and control groups were not significant (P >0. 05). The staffs exposure to static magnetic fields compared with the national exposure limits were in the acceptable level. However، MRI devices were assigned to be the most important sources of static magnetic fields. While the available evidences in the scientific literatures in the worldwide are not sufficient to draw any conclusions about potential health effects of magnetic field، it is suggested that، health and training programs were applied to increase the awareness of staffs

since faculty members are among the most important assets of higher education institutes، surveying and identifying factors associated with these sources which can be effective on their performance & stress، have gained increasing importance. Accordingly، the aim of this study was surveying the mediating effect of individual accountability in causal relations among conscientiousness، agreeableness، and stress and job satisfaction of faculty members. To conduct this study a sample consisting of 250 faculty members in three state universities were chosen using random stratified sampling. The data were gathered through NEO big five factor inventories and stress، job satisfaction and individual accountability questionnaires. To evaluate the relations among latent variables، measured in conceptual model، the structural equation modeling was used. The results showed that the personality trait of conscientiousness bears a negative and significant relation with stress، a positive and significant relation with felt accountability،and the personality trait of agreeableness bears a positive and significant relation with satisfaction and a negative and significant relation with accountability. The results also showed that the relation between conscientiousness and job satisfaction is mediated through felt accountability. The mediating role of the felt accountability in the relation between the personality trait of agreeableness and job satisfaction was confirmed. According to the results، individual accountability affects the relation among personality traits، stress and job satisfaction of faculty members. The results put emphasis on the necessity of reassessing the mediating role of individual accountability in surveying the causal relation among personality traits of conscientiousness، agreeableness، and stress and job satisfaction.

Evaluation of the contractor’s HSE is a key issue for the employer that influences the selection of a contractor. An appropriate method of assessment can play a significant role in the selection of qualified contractors. This paper presents a new method for ranking of contractor’s HSE at pre-contract stage of a project. To develop this new evaluation method، the c ontracts were categorized in 3 groups of advanced، medium and preliminary. In order to pre-assess the contractors’ status prior to their participation in bids، an HSE data questionnaire was developed in the frame of 40 questions. Then 29 indices were developed for primary HSE assessment based on International Association of Oil and Gas Producers (OGP). Because the role of each index is different in each category of contracts thus، seven elements of HSE model were weighted on the basis of contract category. Contractors scoring system was developed in each category of contract based on the obtained weights. Finally the contractors were categorized in four groups of A، B، C and D based on their scores obtained from their HSE evaluation. The results revealed that each term of HSE have different weight in each contract category. In advanced (group 1) and medium (group 2) contracts، the leadership plus commitment (coefficient of 4. 9 and 4. 3 respectively) and in preliminary contracts the execution and monitoring (coefficient 3. 3) have the highest weights. The Strategy and goals have the minimum weight in all 3 types of contracts (e. g. 4. 4 in advanced، 3. 6 in medium and 2. 4 in preliminary contracts). The minimum score required for an A group contractor to get an advanced contract is 537 while the maximum score of a D group contractor to obtain a preliminary contract is 123. The new developed method is able to rank the HSE of contractors prior to sign the contract.

Fatigue is indicated as a factor in occupational accidents and diseases and it can reduce individual efficiency. In shift workers who experience sleep disturbance، the occupational accidents and diseases occurring can be aggravated by fatigue. The present study aims to investigate the fatigue intensity and its relationship to insomnia severity among employees of Tehran rolling and steel production company. This descriptive analytical study had been done among 180 workers of the mentioned company. Data collection was done by face-to-face survey method and using the standard questionnaires. Results showed that the fatigue score among fixed-dayshift and rotating-shift workers was 6 and 7 respectively and fatigue level for both groups was 4. In all symptoms associated with fatigue average score of rotating-shift were higher than dayshift and there was a significant difference between them. Relationship between the symptoms of fatigue with Insomnia Severity Index was significant. Warehousing received the highest scores of fatigue and severity of insomnia between different tasks under study. Our findings indicate that level of fatigue and severity of insomnia among workers of industry is very high. Since this can lead to the occupational accident and reduction efficiency، it is necessary to provide facilities for personnel such as reducing working hours، doing regular rest and exercise during working time، paying sufficient attention to humanitarian needs and improving work system.

In automated excavation operations especially excavating big tunnels with high operation speed the application of Tunnel Boring Machine (TBM) has been prevalent. Tunneling construction projects especially TBM excavating operations have experienced some accidents in recent years. Hazard control must be done through the process of risk management. This study was done w ith goal of risk analysis of automated excavation operations in one of the water transfer tunnel projects.

In this study for risk analysis، energy trace and barrier analysis technique was used. In data gathering process were used observation method، worker experience and judgments، checklist، standards & regulations and incident records. Recognition of energy sources، targets، probability and severity of hazards were done by competence experts in various team works. The identified risks were prioritized and control measures were recommended.

In this study 51 hazardous energy sources in 6 energy categories were recognized. These identified energy sources included physical energy 29. 4%، chemical energy 19. 6%، mechanical energy 41%، electrical energy 8% and natural energy 2%. The crane section by 19. 5%، shield by 10% and cutter head by 10% were the most and the least dangerous part of tunnel boring machine in excavation process.

Based on the findings of the study، TBM operations include various energy sources. Energy trace and barrier analysis technique can be used effectively in risk analysis of TBM operations.