مجله بهداشت و ایمنی کار
سال سوم شماره 3 (پاییز 1392)

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. 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. 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. 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.

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. 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. 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. 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.

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. 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. 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. 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.

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. 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. 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). 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.

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. 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). 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. 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.

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. 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. 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. 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.

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

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. 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. 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