JOURNAL OF OCCUPATIONAL HYGIENE ENGINEERING
Year:2016 | Volume:3 | Issue:2|Papers Count:8

Introduction: Liquefied Petroleum Gas (LPG) storage tanks contain large volumes of flammable and pressurized gases. Release of these fluids can lead to disastrous accidents such BLEVE, and fiery explosion. Therefore, identifying the causes, consequences, probabilities, and scenarios of accidents using Bowtie technique, that is a combination of Fault Tree Analyses (FTA) and Event Tree Analyses (ETA), is imperative and the purpose of this study.Methods: This study was performed in 2016. The hazards of the mentioned study in Tehran Refinery LPG tanks were identified by Fault Tree Analyses and the consequences of the top event were predicted by Event Tree Analyses. Probabilities of the events were calculated and the accident route, from the causes phase to consequences phase, was drawn by the Bowtie diagram.Results: In total, 21 events and 11 minimal cut sets with their occurrence probabilities and importance measure were determined at the left side of the Bowtie diagram. Also, 9 consequences and scenarios of the top event were determined on the right side of the diagram. The occurrence probability of the top event (LPG release of spherical tanks) was calculated as 3.45×10-2.Conclusions: All factors involved in the occurrence of accidents and their consequences are showed in the Bowtie diagram. According to the obtained data, failure of cathodic protection systems and instrumentation, and overflow of tanks are important defects of LPG tanks. Due to the high probability of consequences, preventing systems such as cooling systems and fire stop systems are required for installation in the studied unit to reduce the consequences of accidents.

Introduction: Safety culture is a term, which is used repeatedly in the assessment of safety status of companies. The aim of the present study was to investigate the parameters and factors influencing organizational safety culture in the Iranian thermal power plants industry.Methods: The triangulation approach was used for data generation in this grounded theory study. Nineteen participants from a variety of work groups at three thermal power plants of Iran (Shazand, Shahid rajaei Ghazvin, and ramin Ahwaz) took part in focus group interviews, individual interviews, field observations, and focus group discussions.Thematic analysis was conducted to emerge and identify contributing factors.Results: The thematic analysis identified 9 sets of parameters for achieving safety culture as follows: (1) training, briefing and competency, (2) vision, leadership and commitment, (3) laws, rules and work procedures, (4) safety and crisis management, (5) individual agents, (6) Management style and organizational communication, (7) participation and commitment of personnel, supervisors and middle managements, (8) non-organizational agents, and (9) to make available foundations and source managements.Conclusions: The results indicated that an improvement in each parameter is necessary to achieve top safety culture. Moreover, proportionate to the conditions of each company, measures should be taken for the imporovement of actions of safety status and to accomplish pre-determined targets.

Introduction: One of the most common chemical exposures is organic solvents in the workplace and some of them are toxic to human health. The purpose of this study was to determine the effect of organic solvents on physiological parameters of exposed people in the industry.Methods: This study was cross-sectional, descriptive and analytical, and 50 workers were studied in a home appliance industry. Data were collected in three stages: 1) through observation and interview, 2) reviewing periodic examinations of workers, and 3) measurement of the concentration of BTEX. Descriptive and analytical statistical analysis was performed with SPSS software version 20.Results: According to the obtained results, spirometry parameters in the exposed group (FEV1=%89.62 ± 10.53) were lower than the non-exposed (FEV1=%97.32 ± 8.92) while the average liver enzymes in exposed workers (SGOT=29.56 ± 9.49 lU/L and SGPT=38.67 ± 17.5 lU/L) was higher than non-exposed (SGOT=17.5 ± 6.38 lU/L and SGPT=21.11 ± 8 lU/L).Conclusions: Long-term exposure to BTEX leads to a reduction in respiratory capacities, and increases liver enzymes. Therefore, with proper engineering and management controls and periodic examination, such problems can be prevented in workers.

Intoduction: Combustible dust particles when dispersed in the air under special conditions have a risk of explosion. Distribution of dust particles in sufficient amount and concentration can cause rapid ignition and explosion. The aim of this study was to assess the risk of combustible dust explosions, in the some related industries in shahroud.Methods: To evaluate dust concentration, the NIOSH 0500 method was used. To determine the combustion risk, risk assessment was conducted using the Failure Mode Effects Analysis (FMEA). The main sources of possible secondary explosion were determined by observation and interviews with managers and supervisors.Results: The concentration of combustible dust in industries showed that the most explosive dust generation was related to the PVC industry with a concentration of 43 ± 74 mg per cubic meter. The FMEA risk assessment results also showed that the most risky equipment in creating sparks and combustion include conveyors, dryers, cutting and drilling equipment, motors and switchgear lightning. Also, the study showed silos with their high storage capacity can be the most likely sources of secondary explosions.Conclusions: This study showed that combustible dust concentration is much lower than the minimum explosive concentration. However, due to the existence of combustion vast resources and huge storage resources of powder products, dust explosion in some of these industries is very important.

Introduction: Musculoskeletal Disorders (MSDs) are one of the most important factors of occupational injuries and disabilities in workplaces. Back injuries are the most common work-related disorders in different industries. The aim of the present study was ergonomics intervention to reduce these disorders.Methods: This interventional study was conducted on 126 preservation and maintenance workers in a cement company by classification sampling. The Nordic Musculoskeletal Disorders Questionnaire, QEC and ergonomics checkpoints were used to collect data before and after the interventions. The interventional program included practical and easy-to-implement solutions for improving safety, health and work conditions, workers’training, and selective and corrective exercise. Data were analyzed by McNemar’s test using SPSS version 22 software.Results: Data analysis showed a significant difference (P-value<0.001) between the prevalence of disorders during the one week before and after the interventions. The prevalence of disorders for lower back and knee were 62.70% and 60.32%, which were reduced to 46.03% and 43.65 after the intervention, respectively.Conclusions: According to QEC method, 83 maintenance workers (65.87%) were at high risks, and the prevalence of lower back and knee pains was high, that applying simple and inexpensive solutions, participatory solutions of ergonomics checkpoints and selective corrective exercise led to a significant reduction in these disorders.

Introduction: Due to the widespread use of toxic chemicals in most workplaces which can lead to toxic effects on human, various chemical extraction techniques have been defined for the analysis of these toxic substances in air, water and biological samples. The purpose of this research was the extraction of toluene and methyl ethyl ketone from aquatic samples with needle trap device together with one commercial sorbent.Methods: In this research, needle trap device was used to extract toluene and methyl ethyl ketone in aquatic samples. Needles (size 20) were packed with polydimethylsiloxane (PDMS) and extraction was performed using dynamic headspace needle trap device. The analysis was conducted using gas chromatography with flame ionization detector and optimized extraction conditions of the two substances were obtained.Results: Results showed that the optimum temperature and time of extraction was similar for toluene and methyl ethyl ketone (30°C, 30 minutes); but, the reproducibility of results and the calibration curve obtained for toluene were better than those of methyl ethyl ketone.Conclusions: Needle trap technique is inexpensive, sensitive and portable; also, this method has a good recovery to extract small amounts of toluene and methyl ethyl ketone from aquatic samples with PDMS.

Introduction: In view of the increasing attention to the health of the workforce and on the other hand the increase in scientific outputs in the format of scientific and research papers, the aim of this study was to monitor the status of technical articles of Iranian journals in the field of health workforce.Methods: This retrospective cross-sectional study was conducted for a period of ten years (2005-2015) on the specialized field occupational health journals. The data were collected based on content analysis method with researcher-made checklist and using census articles.Results: The extracted data, from 927 articles from five specialized journals in the period of ten years, represented the growing trend in publication of Persian and English articles.Most researches had been respectively conducted in physical and mental health scopes.According to the type of harmful factors, ergonomic factors with 24.27% had the largest portion of articles and researches. Only 11.54% of the reviewed articles were interventional studies. In addition, cohort studies were not found among the articles.Conclusions: The findings of this study which were of the scientometrics type, represented the imbalance in health workforce researches, so that hazardous agents such as ergonomic factors had strong emphasis and some health aspects such as public health were neglected.According to the current situation, setting national priorities in order to balance the distribution of health force researches is necessary.

Introduction: One of the most common causes of occupational injuries in industrialized and developing countries is musculoskeletal disorders. Determining the risk factors of musculoskeletal disorders can be helpful, choosing the right method for interventions and detailed studies. This study aimed to evaluate the ergonomic risk factors in operators of pressurized irrigation equipment production.Methods: This cross-sectional study was conducted in a pressurized irrigation equipment manufacturing company. In this study, a new method based on observation was used to evaluate the ergonomic aspects of operators’ activities. In order to assign tasks and sub-tasks, direct observation and video recording equipment were used. Ergonomic assessment was carried out on all the sub-tasks identified. Then, the criticality of the task was determined.Results: Among the tasks identified, 53 highly critical, 61 critical and 82 lowly critical postures were determined. The ergonomic points in the ball valve production line were 0.6 and 0.68 respectively for tow operators. For drop valve and automatic valve production lines, the ergonomic points were 0.52 and 0.67, respectively.Conclusions: According to the results, the posture analysis method used in this study was easy and accurate. The advantage of this method is 14 ergonomic domains that covered the whole body and time fragment of each task. Findings of previous studies showed good correlation between results from this method and the OCRA method. In this study, The most critical posture was related to operator's wrist; so, it is recommended that control measures on wrist posture correction should be considered.