Exploring the Contributory Factors of Confined Space Accidents Using Accident Investigation Reports and Semistructured Interviews

BACKGROUND: The oil and gas industry is one of the riskiest industries for confined space injuries. This study aimed to understand an overall picture of the causal factors of confined space accidents through analyzing accident reports and the use of a qualitative approach. METHODS: Twenty-one fatal occupational accidents were analyzed according to the Human Factors Analysis and Classification System approach. Furthermore, thirty-three semistructured interviews were conducted with employees in different roles to capture their experiences regarding the contributory factors. The content analyses of the interview transcripts were conducted using MAXQDA software. RESULTS: Based on accident reports, the largest proportions of causal factors (77%) were attributed to the organizational and supervisory levels, with the predominant influence of the organizational process. We identified 25 contributory factors in confined space accidents that were causal factors outside of the original Human Factors Analysis and Classification System framework. Therefore, modifications were made to deal with factors outside the organization and newly explored causal factors at the organizational level. External Influences as the fifth level considered contributory factors beyond the organization including Laws, Regulations and Standards, Government Policies, Political Influences, and Economic Status categories. Moreover, Contracting/Contract Management and Emergency Management were two extra categories identified at the organizational level. CONCLUSIONS: Preventing confined space accidents requires addressing issues from the organizational to operator level and external influences beyond the organization. The recommended modifications provide a basis for accident investigation and risk analysis, which may be applicable across a broad range of industries and accident types.

[Effect of the mental and physical disorders status of Tehran's public transportation system bus drivers on the occurrence of crashes]

In many studies, chronic diseases are associated with incidence of driving accident. The main objective of the present study is investigation the effect of physical and mental disorders status of bus drivers on the occurrence of crashes. This research is a cross-sectional and descriptive-analytical study that was performed on 665 bus drivers' public transportation system in Tehran. The samples were selected randomly and to the proportion of working population in nine bus systems or areas. In order to investigate physical [disease] and mental [family problems] disorders demographic information and health status questionnaires were used. The relationships between variables analyzed through Univariate analysis of variance [UNIANOVA] and Kendall's tau-b tests by SPSS 16 of software. The results showed 68.7% of drivers with mental disorders [with family problems] in both groups from healthy and unhealthy [physical diseases] drivers' had average 3.2 crashes in the last three years. Furthermore the tests of Univariate analysis of variance [UNIANOVA] [F = 0.43, p <0.05] and Kendall's tau-b [r = 0.112, p <0.01] showed significant and positive correlation between family problems and the number of self-reported crashes over the previous three years. Because of the increased risk of crashes among drivers suffering from mental problems, it is assumed that the removal of economic problems and the use of psychological consultations will reduce family problems including poor emotional relationships of family members which play an important role in increasing attention and concentration of the drivers while driving and consequently reducing traffic crashes.

[Combined application of wet-bulb globe temperature and heart rate under hot climatic conditions: a guide to better estimation of the heat strain]

Working under hot climatic conditions, especially in summer, has a high potential for inducing heat strain in workers. The wet-bulb globe temperature [WBGT] index has an inherent limitation to estimate the heat strain due to not taking into account the non-environmental factors. The aim of this study was to evaluate the combined application of WBGT index and a physiological strain index [PSI[HR]] based on heart rate in the estimation of the heat strain under hot climatic conditions. This cross-sectional study was conducted on 122 men in the center and south of Iran [51 and 71 workers from Isfahan steel company and Assaluyeh national petrochemical company, respectively] between July and September 2010. The WBGT index, heart rate and the auditory canal temperature were measured at rest and during the work. Data were analyzed using descriptive statistics and logistic regression. Results of the logistic regression analysis revealed that the WBGT index is a poor predictor for heat strain with a sensitivity and specificity of 53% and 65%, respectively. However, the combined application of the WBGT and PSI[HR] indexes was a better predictor for heat strain and its sensitivity and specificity were 75% and 69%, respectively. A combined application of the WBGT and PSI[HR] indexes can be a valid estimator of heat strain for hot climatic conditions in the center and south of Iran

[Relationship between safety climate factors and the risk of dangerous situations in height among construction workers]

Falling from height is considered one of the most important risks in construction sites and many workers through non-compliance with safety tips lose their lives. This study was conducted in order to survey the relationship between safety climate factors and behavior of workers working in potentially dangerous situations in height among construction workers. For evaluation of safety climate factors a safety climate questionnaire and for behavior of workers in potentially dangerous situations behavioral questionnaire including potentially dangerous situations, work on ladders and scaffolding has been used. Factor analysis to analyze safety climate factors and Binary logistic regression using SPSS software for the influence of factors on behaviors in potentially dangerous situations are used. Factors of safety attitudes of workers, the level of risk in construction site and working relationships derived from factor analysis are 57% of the total variance. Situation of working on scaffold without Guard rail and protect the edges, access to the scaffold by going up and down connections and the ladder not secure are usually seen in the most construction sites. Results indicate that workers have awareness of work in dangerous situations but perhaps management ignorance of safety issues and not doing engineering controls to eliminate potentially dangerous situations can be mentioned as the cause of accidents as may result safety issues to be ignored by construction workers working in dangerous situations

[Evaluation of chlorine dispersion from storage unit in a petrochemical complex to providing an emergency response program]

Chlorine gas is a dangerous material that is used in chemical industries. In spite of the attempts for chlorine gas release control, sudden releases still occur in the related installations. Not taking proper emergency measures after chlorine gas dispersion may result in serious harm to health of the personnel and the people residing around the industrial area. The present study considers chlorine gas dispersion scenarios, determines emergency levels and presents an optimized pattern for more effective and faster response with the least required measures for emergency conditions control. In the present paper by using Hazard and Operability Study [HAZOP] and risk matrix the possible scenarios of chlorine gas dispersion in storage tanks unit of a petrochemical complex were considered. Then the intervals of these scenarios were determined with a view to Emergency Response Planning Guideline 1-2-3. With a view to the intensity of pollution extension and the population exposed to risk the scenarios were classified in the four emergency levels defined by Center for Chemical Process Safety [CCPS]. Finally for each class of scenarios with a view to the related emergency level an optimum pattern of response plan in emergency conditions was presented. On the basis of the results of this study, chlorine gas dispersion scenario of the catastrophic explosions of the tank and scrubber system failure in the summer was classified in emergency level 4, in the winter in emergency 3, chlorine gas dispersion due to chlorine lines rupture in the summer and winter in emergency level 3 and chlorine gas dispersion due to leakage of flanges and gaskets in emergency level 2 according to emergency levels of CCPS. The results of this study showed that systematic process risks analysis by use of risks recognition methods such as HZAOP and consequence analysis may have an effective role in recognition of the possible major events. Also by classification of release scenarios in CCPS emergency levels, we can select the best pattern for emergency conditions managements

[Survey of nano filtration performance for hexavalent chromium removal from water containing sulfate]

Geological situation and/or anthropogenic contamination contain an increased concentration of ions such as hexavalent chromium as well as some other dissolved components such as sulfate in the upper of the established MCLs [50microg/L]. In this paper, simultaneous removal of Cr [VI] and sulfate from water was investigated using nanofiltration as a promising method for reaching drinking water standards. For varying pressure, pH, anion and cation solution effect, Sulfate and Cr [VI] concentration which have chosen were levels found in drinking water sources [Cr=0.1- 0.5mg/L] and [SO[4][-2]= 100-800mg/L].Experiments were performed using NaCl, Na[2]SO[4],K[2] Cr[2]O[7]and anhydrous CrCl[3]. 6H[2]O which prepared with de mineralized water on procedure detailed in standard methods. All salts were purchased from Merck Corporation with purity over 99%. The results for hexavalent chromium experiments showed that when the concentration decreases, the chromate anions were given a better retention to 4 bars [96%]. But when the concentration increases, concentration polarization led to increased removal of Cr [VI] [98%]. For Cr [III] the influences of the ionic strength as well as the concentrations were strongly dependant on rejection but operating pressure were found weak. In addition, with increasing total dissolved solids, perfect rejection of chromium was seen. The effect of pH showed that better retention was obtained at natural and basic pH. This study indicates that the nature of anions and cations, driven pressure and pH have significant effect on nano filtration operation. Research findings show that it seems nano filtration is a very good promising method of simultaneous removal of Cr [VI] and sulfate from water

[Study of nitrate removal from water resources using magnesium powder]

Nowadays nitrate concentrations in surface water and especially in groundwater have increased in many locations in the world. Since nitrates cause many health and environmental concerns, increased nitrate concentrations in groundwater have led to rendered aquifers unusable as water sources. So, as the water demand is still increasing the throughout the world, decreasing the nitrate concentration in drinking water is imperative. Magnesium powder has been determined to be potentially useful for the removal of nitrate in the water environment. This research is aimed at subjecting the kinetics of nitrate chemical reduction by Mg[0] to an analysis of some factors affecting the chemical denitrification. Nitrate concentrations determined in 220 nm using a spectrophotometer. To determine the performance of nitrate removal by Mg[0] powder, double distilled water was used for preparation of reagents and simulation of contaminated water with nitrate.All experiments were triplicate and the averaged results were reported. Kinetics analysis from batch studies revealed that the denitrification reaction with Mg[0] powder appeared to be a first-order with respect to substrate and the observed reaction rate constant [k[obs]]. The effects of mixing intensity on the denitrification rate suggest that the denitrification appears to be coupled with oxidative dissolution of magnesium through a largely mass transportlimited surface reaction. Also in the denitrification by Mg[0] determined that Mg[0] dose related with kobs[R[2]>0/99]S In this research was determined that denitrification effectively by Mg[0] powder can achieved in a wide range of concentrations under atmospheric conditions and without pH controlling within short reaction time. Denitrification rate was related to some parameters such as contact time, Mg[0] dosage, mixing rate and initial nitrate concentration

[Reduction of hexavalent chromium from aqueous solution using modified zeolite cationic surfactant]

Hexavalent Chromium is an important contaminant in surface and ground waters and removal from contaminated water and waste water has received interest in recent years. Modified Zeolite with cationic surfactant can remove Cr[VI] from contaminant water. The aim of this research is investigation of Cr [VI] removal from aqueous solutions and its effective parameters by using Modified Zeolite with cationic surfactant. In this research the efficiency of Cr[VI] removal and impact of the important parameters including adsorbent dose, pH and contact time in the batch system was studied. The results of this research showed that SMZ can remove more than 90% Cr[VI] in the concentration 0.1-1.25 mg/l with optimum dose 0.3 gr and pH=6, 120 minute in contact time. Modified natural zeolite have significant potential in Cr[VI] removal from contaminated water. Maximum percent removal of Cr[VI] was in the pH=6 and 120 minute contact time. Adsorption data in the equilibrium was fitted with Langmuir isotherm. Separation factor was between 0 and 1 that indicates the favorable condition for Cr[VI] adsorption on the SMZ

Determining the effect of stress of threshold limit value of noise with shrill and bass frequencies on antioxidation and lipid peroxidation variations of liver tissue of rabbit

Background and Purpose: Noise, in high intensity, is one of the major physical stressors. The aim of this study was to determine the effect of stress of threshold limit value of noise with shrill and bass frequencies on antioxidation and lipid peroxidation variations of liver tissue of rabbit

Methods and Materials: This experimental study was carried out on 18 male white New Zealand rabbits at Tarbiat Modarres University in 2004. Rabbits were randomly divided into three groups: Control Group [unexposed to noise], Group 2 exposed to noise [85 dB SPL,< 250-3540Hz, 8 h/day, 96 h] and Group 3 exposed to noise [3540Hz-20kHz, 85 dB SPL, 8 h/day for 96h, 12 days]. The obtained data were analyzed in SPSS. One-way ANOVA and post hoc Tukey test were used for comparing means across the groups; differences at P<0.05 were considered statistically significant

Results: The findings indicated that Malondialdehyde [MDA] levels were 5.5, 5.54, and 5.71 in the groups 1, 2, and 3 respectively, and that the glutathione level was 0.131 g per micromol liver tissue across three groups. It was also found that the differences were not statistically significant [P=0<0.05]

Conclusion: According to the findings of the present study, despite limited variation in Malondialdehyde [MDA] levels induced by noise with 85dBA frequency, it does not induce significant changes in levels of Malondialdehyde [MDA] and glutathione in the liver tissue of rabbits

Study of factors related to accidents occuring during the construction phase of oil, gas and petrochemical projects

Construction phase in industries is a dynamic process that is naturally and intrinsically dangerous and as it becomes more complicated, the accidents rate also increases. One should note that without considering a model, one could not obtain useful and reliable information and method to prevent accidents. Therefore, to achieve useful methods for preventing accidents, it is desirable to consider a model. The general goal of this study was presentation of a model. A model is the reflection of a fact. In other words, it should be said that the model represents a system or process whose behavior can be predicted. Models are therefore used for understanding the behavior of actual terminals and show a theory in the way that covers important variables for describing phenomena and instead, ignore factors of low importance in the expression of those phenomena. This study was a research article conducted in 2004-2005 in the Assaluyeh region. Data was gathered from accident reports present in security and health records of the projects and also statistics present at the treatment centers. In this study, an analytical model [multi-regression] was presented to describe the impact of effective and deep factors on the possibility of an increase in accidents leading to death, through measurement of the effects of independent variables on the dependent variables. For this purpose, the structure of 50 accidents that led to death were studied along with another 2700 accidents, and after studying the accident reports and related documents, observing operations and equipment, counseling with accident observers and an expert team of managers, supervisors and engineers, and simulation of some accidents, unsafe conditions and functions, mismanagement and use of worn out and defective tools, equipment, devices and machinery were considered as the four independent variables and the job accidents leading to death were considered as dependent variables. The relationship between independent and dependent variables, evaluation of regression coefficients and the test of different models were based on multi-regression analytical model and analyzed using Eviews software program. The final findings of this study, while specifying the possibility of occurrence of accidents leading to death with the existence of any of the independent variables showed that among the independent variables, unsafe conditions and mismanagement have relatively more important roles to play in the occurrence of accidents leading to death such that in conclusion, these factors have been defined as root causes in the model. Since the adjusted coefficient determined for the model in this research was 0.99; that is, the specified model could describe 99 percent of changes related to the number of job accidents leading to death and it is only for one percent of other accidents that there was no justified answer. In another words, those causes were not seen in the model. Therefore, it could be concluded that this research as compared to similar researches gained more useful results. Thus, by omitting or lowering unsafe conditions and mismanagement factors, accidents resulting in deaths can be reduced

Assessment of bagging operators exposure to with PVC airborne particulates

Dust consists of tiny solid particles carried by air currents. These particles are formed by many different processes. One of these processes is polymerization of inert plastic such as Polyvinyl Chloride production plant. According to the Occupational Health and Safety Assessment Series requirements, section 4.4.6, occupational health and safety risks must be defined and controlled where needed. This field study was conducted to evaluate the occupational exposure of packaging operators to airborne polyvinyl chloride dust in order to health risk assessment and recommend feasible controlling methods. The mass concentration of polyvinyl chloride particulate was measured in two fractions according to the particle size that expressed as total and respirable particulates. The Air Sampling Methods, Methods for the Determination of Hazardous Substances 14/3, of Health and Safety Executive were used as a standard sampling protocol. The average mass concentrations for respirable and total particulates were measured 3.54 +/- 0.3 mg/m[3] and 11.89 +/- 0.8 mg/m[3] respectively. Also health risks of studied condition were estimated as significant level, category one, therefore the risk must be reduced below the standard level. According to the work requirements to reduce the emission rate and mitigate the health risk exposure, a local exhaust ventilation system design was recommended for bag-filters of hopper tank

[Assessment of factors associated with explosion of gas-fuel in fire-tube boilers]

There are many factors with different degrees of importance in explosion of fire-tube boilers and hence, reorganization, assessment and ranking of such factors by an accurate analytical method could be used as a guideline for experts related to safety programs. This study was planned to determine all effectual factors associated with explosion of oil fuel, the probability of occurrence in a specific area of industry, and also ranking of basic events. Fault tree analysis method was used in studying four fire-tube boilers located in one of the factories of Alborz Industrial City [Qazvin, Iran] to determine the effective events for occurring expected explosion accident and also to show their association. All basic events were further ranked by qualitative method. Developed fault tree showed 76 events which were connected through 42 logical gates. There were 36 basic events ranked in 11 levels according to their qualitative importance. Ranking of basic events showed that the human error factor [in management planning level] has the highest order among the factors with potential to cause boiler explosion

new exhaust ventilation system design software

A Microsoft Windows based ventilation software package is developed to reduce time-consuming and boring procedure of exhaust ventilation system design. This program Assure accurate and reliable air pollution control related calculations. Herein, package is tentatively named Exhaust Ventilation Design Software which is developed in VB6 programming environment. Most important features of Exhaust Ventilation Design Software that are ignored in formerly developed packages are Collector design and fan dimension data calculations. Automatic system balance is another feature of this package. Exhaust Ventilation Design Software algorithm for design is based on two methods: Balance by design [Static pressure balance] and design by Blast gate. The most important section of software is a spreadsheet that is designed based on American Conference of Governmental Industrial Hygienists calculation sheets. Exhaust Ventilation Design Software is developed so that engineers familiar with American Conference of Governmental Industrial Hygienists datasheet can easily employ it for ventilation systems design. Other sections include Collector design section [settling chamber, cyclone, and packed tower], fan geometry and dimension data section, a unit converter section [that helps engineers to deal with units], a hood design section and a Persian HTML help. Psychometric correction is also considered in Exhaust Ventilation Design Software. In Exhaust Ventilation Design Software design process, efforts are focused on improving GUI [graphical user interface] and use of programming standards in software design. Reliability of software has been evaluated and results show acceptable accuracy

[ effect of microwave on micronucleus induction and nuclear division index changes on Balb/c mice lymphocytes

Biological effects of microwave radiation on living creatures have been the focus of many investigations over the last decade and the influence of different wave parameters such as frequency, power, exposure time, and modulation has been elucidated. The main purpose of the present study was to investigate the effect of microwave radiation on alterations of micronucleus induction and nuclear divisions index under different conditions. A total of 48 Balb/c mice divided in eight groups [7 as cases and 1 as control] were exposed to microwave generator while restrained in specially designed Plexiglas chamber. Later, the frequency of micronucleus in binucleated lymphocytes and NDI was evaluated using micronucleus assay on mouse lymphocytes. Microwave radiation conditions [frequency, power, modulation and exposure time] showed no significant effect on frequency of micronucleus, however, the nuclear division index was significantly decreased under such conditions. Based on data found in our study, the microwave radiation as we used during the present work, caused significant effect on nuclear division index in mouse lymphocytes

[ comparison of effects of toluene, especially noise and toluene along with noise per auditory brain stem response on rabbit]

An increase more than definite limit in sound pressure level is harmful for health mean while, organic solvents like toluene are used in industrial processes with noise widely. So, this study was going to investigate the relationship between toluene [1000ppm], noise and toluene along with noise [frequencies 4000 and 8000 Hz] per auditory Brain Stem response [ABR] on rabbits being exposed to these contaminants. This survey was done in experimental method on 48 three months old, male adult white New Zealand rabbits [1800 +/- 200 g body weight], in nine groups which were exposed to toluene [1000 ppm], noise [4000 Hz], 100 dB SPL, combination of toluene and noise conducted using click and tone burst stimuli in 110dB sound pressure level. Then the results of ABR test of groups exposed were analyzed by SPSS software. One-way variance [ANOVA] analysis was used to compare the groups and Turkey test was applied as a post hoc test for comparison among the groups. P values were obtained by Turkey test. t-test was conducted for comparison of ABR test results after and before exposing groups. Differences at the level of P<0.05 were considered statistically significant. The results of the study showed that Exposing rabbit's to combination of toluene and noise caused hearing impairment in all of frequencies auditory especially in frequencies 250, 500 and 1000Hz. So that, wave five in ABR test [tone burst stimuli] didn't formed in 250-1000 Hz 4.84 +/- 0.07 ms, group exposed to toluene 5.18 +/- 0.07ms, noise group [4000hz] 5.5 +/- 0.07 ms and in combination noise and toluene group [4000Hz] 5.79 +/- 0.07 ms. The mean of latency time of V wave in control was compared to that group noise group P=0.01, toluene group P=0.07 and combination noise and toluene group P=0.0001. According to the result of this study, both toluene and noise exposure caused the rabbits in hearing impairment but combination of toluene and noise exposure in frequencies of 4000Hz and 8000Hz was much worse than hearing impairment. So that, the ABR test on rabbits didn't formed V wave in low frequency

removal of color and COD from wastewater containing water base color by coagulation process

In this study acrylic water base color was removed from synthetic wastewater using coagulation process. Experiments were conducted on the sample containing 100 mg/L and 400 mg/L of acrylic water base color. Destruction of color by means of coagulation/flocculation techniques using ferrous sulfate, alum, lime and polyelectrolyte [cationic, anionic and non ionic].The study was performed in a systematic approach searching optimum values of alum and FeSO[4] concentration, pH and temperature. All the experiments were run in a laboratory scale. The obtained results show that treatment with alum and ferrous sulfate alone proved to be very effective in removing the color [> 99%] and part of COD [60-70%] from aqueous solution. Lime alone did not significant change on COD and color removal

Effect of sound conditioning on protection of hearing and plasma antioxidant activity in rabbits

Noise is one of the major physical pollutants in present societies. Sound conditioning is used as means of protecting against noise-induced hearing loss. The status of plasma antioxidant system during sound conditioning is important. To study possible involvement of plasma total antioxidant ability in noise-induced hearing loss and sound conditioning. This study was carried out on 24 male white New Zealand rabbits [6 in each group]. The rabbits were assigned to the following four groups: [1] Noise exposure [250Hz-20000Hz, 110 dB for 8h/day for 12 days], [2] Conditioning noise exposure [80dB for 10 days and 110 dB for 12 days], [3] Noise exposure [80 dB] and [4] control group. Auditory Brain stem Response [ABR] was measured and compared in all pre- and post-exposures groups. Plasma antioxidant power was also measured post exposure. FRAP was assayed in plasma sample collected from each animal using TPTZ reagent. The ABR assay using click in different experimental groups showed that the absolute latency of 5[th] wave generation was statistically significant in first group as compared to other groups [p=0.0001]. Likewise ABR assay using tone burst showed a higher absolute latency observed in group 1. FRAP assay indicated that the antioxidant parameters were suppressed in group 1 when compared with data obtained from other groups [p<0.05]. The ABR results found in our study, confirmed sound conditioning in rabbits exposed to 80 and 110 dB. Furthermore, changes in FRAP in rabbits studied in our experiment was indicative of involvement of antioxidant system in sound conditioning however, further studies needed

Degradation of MTBE using Fenton reagent

Methyl tertiary-butyl ether [MTBE] has been commonly used as a fuel additive because of its many favorable properties that allow it to improve fuel combustion. Unfortunately, increased production and use have led to its introduction into the water supplies. Accordingly, research studies have been initiated to investigate the treatment of contaminated water. Degradation of MTBE in aqueous solution by Fenton reagent [Fe2+ and H202] was investigated. This study used Fenton reagent to oxidize MTBE with an attempt to explore the behavior of MTBE decomposition and measure how factors such as pH, [H202] and [Fe21 may influence the degradation of MTBE, and finally the optimum conditions were obtained. Under optimum conditions of 50 mL H202, 0.65 g/L Fe2+, pH=3-4 and room temperature, the initial 1000 mg/L MTBE solution was reduced by 99% within 120 min. The results showed that application of Fenton reagent was an effective method for degradation of MTBE