Evaluation of photoionization detector performance for measuring the airborne toluene

Background and aims: In the field of chemical agents at workplaces, traditional measurement method for assessing the volatile organic compounds (VOCs) concentration is using a gas chromatograph generally equipped with a flame ionization detector (GC-FID). However, there are some limitations in working with this equipment including equipment accessibility, necessity of highly trained operators, and the high cost of sample analysis. The aim of this study was to evaluate the performance of photoionization detector (PID) as a substitution for GC-FID in the measurement of toluene as a representative of the VOCs in experimental studies. Methods: This study was carried out by an experimental set up for generating toluene known concentrations at 5, 20, 50, 100, 200, 500 and 1000 ppm with relative humidity 13 ±2. The concentration values were measured with PID as well as the National Institute of Occupational Safety and Health (NIOSH) 1501 reference method and results were compared. Results: The results showed a significant difference between the two methods at concentrations higher than 50 ppm while there was no significant difference at 5 ppm and 20 ppm. The correlation coefficient of the toluene concentrations at 5 to 1000 ppm was 0.999. The correction factor for the PID was 1.05 at the studied concentration range. Conclusion: Although the results presented by PID were different from those extracted from the NIOSH reference method, the response was linear. Thus, in studies of measuring airborne concentrations of toluene using this type of detector; the reading values must be corrected by the calculated correction factor

Structural Modeling of Safety Performance in Construction Industry

Background: With rapid economic development and industrialization, the construction industry continues to rank among the most hazardous industries in the world. Therefore, construction safety is always a significant concern for both practitioners and researchers. The objective of this study was to create a structural modeling of components that influence the safety performance in construction projects. Methods: We followed a two-stage Structural Equation Model based on a questionnaire study (n=230). In the first stage, we applied the Structural Equation Model to the proposed model to test the validity of the observed variables of each latent variable. In the next stage, we modified the proposed model. The LISREL 8.8 software was used to conduct the analysis of the structural model. Results: A good-fit structural model (Goodness of Fit Index=0.92; Root Mean Square Residual=0.04; Root Mean Square Error of Approximation=0.04; Comparative Fit Index=0.98; Normalized Fit Index=0.96) indicated that social and organizational constructs influence safety performance via the general component of the safety climate. Conclusion: The new structural model can be used to provide better understanding of the links between safety performance indicators and contributing components, and make stronger recommendations for effective intervention in construction projects

Factors influencing unsafe behaviors and accidents on construction sites: A review

Objective. Construction is a hazardous occupation due to the unique nature of activities involved and the repetitiveness of several field behaviors. The aim of this methodological and theoretical review is to explore the empirical factors influencing unsafe behaviors and accidents on construction sites. Methods. In this work, results and findings from 56 related previous studies were investigated. These studies were categorized based on their design, type, methods of data collection, analytical methods, variables, and key findings. A qualitative content analysis procedure was used to extract variables, themes, and factors. In addition, all studies were reviewed to determine the quality rating and to evaluate the strength of provided evidence. Results. The content analysis identified 8 main categories: (a) society, (b) organization, (c) project management, (d) supervision, (e) contractor, (f) site condition, (g) work group, and (h) individual characteristics. The review highlighted the importance of more distal factors, e.g., society and organization, and project management, that may contribute to reducing the likelihood of unsafe behaviors and accidents through the promotion of site condition and individual features (as proximal factors). Conclusion. Further research is necessary to provide a better understanding of the links between unsafe behavior theories and empirical findings, challenge theoretical assumptions, develop new applied theories, and make stronger recommendations

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

Background and aims  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.   Methods   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.   Results  On the basis of the results of this study, chlorine gas dispersion scenario of the catastrophic explosion of the tank and scrubber system failure in the summer was classified in emergency level 4, in the winter in emergency level 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.  Conclusion The results of this study showed that systematic process risks analysis by use of risks recognition methods such as HAZOP 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 management

Removal of Toluene from Air Using a Cycled Storage-Discharge (CSD) Plasma Catalytic Process

Abstract: Cycled storage-discharge (CSD) air-plasma catalytic process was used for removing toluene from simulated 40 humid air. The different catalytic activities of HZSM-5 and Ag/HZSM-5 catalysts were entered in a dielectric barrier discharge reactor in two-layer form. The experiments were conducted with different filling layout of HZSM-5 and Ag/HZSM5. It is found that the catalysts filling layout, wt of Ag load on the Ag/HZSM5 layer, the amount of stored toluene at the storage phase, and the discharge gas flow rate were the main factors that could affect the performance of plasma catalytic oxidation of the stored toluene. The performance was maximized when the catalyst-filling layout was 0.5 g HZSM5, followed 0.5 g 5.2 wt g/HZSM5, and the discharge air flow rate was 1 l/min. When the stored toluene in the storage phase was 77 of toluene adsorbing breakthrough capacity of the first layer catalyst, close to 100 of the stored toluene was oxidized, and so the carbon balance and the CO 2 selectivity reached to ~ 100 with no significant O 3 and NO x observed in the outlet. By optimizing the storage and discharge period and discharge gas flow, the electrical energy yield and the performance of toluene oxidation were maximized and the energy consumption was minimized. © 2018, Springer Science+Business Media, LLC, part of Springer Nature

Study of Factors Related to Accidents Occuring during the Construction Phase of Oil, Gas and Petrochemical Projects

Introduction: 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. Methods: 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. Results: 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. Conclusion: 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

Airborne toluene degradation by using manganese oxide supported on a modified natural diatomite

The catalytic combustion of toluene over manganese oxide supported on natural diatomite has been investigated in the paper. The catalyst was prepared by the wet impregnation method and characterized by using the Brunauer Emmett Teller, field emission scanning electron microscopy, X-ray diffraction, X-ray fluorescence and temperature-programmed reduction analysis. The higher activity of the catalyst supported on diatomite for toluene oxidation was obtained at 12� wt Mn loading. It was able to convert 90� of toluene (T90) at 380� �°C. The results indicated that the selectivity towards CO2 was almost 100� and no intermediates, such as CO or other hydrocarbons, were detected. �© 2016, Springer Science+Business Media New York

Liver and kidney serum profile abnormalities in workers exposed to aflatoxin B1 in urban solid waste management centers

Many workers are exposed to health problems arising from molds, fungi, and their toxins during waste processing. Aflatoxin B-1(AFB(1)) level in airborne and settled dust, aflatoxin B-1-albumin (AFB(1)-Alb) adduct in serum, liver and kidney biochemical tests, and body redox change of workers in municipal dry waste-processing sites were investigated. The surface, personal, and area air dust and the blood of workers' samples were collected from the plastic and bread waste-sorting sections in three recycling municipal dry waste sites. Digestion (only for serum samples), passed through SPE cartridge, elution, and collection with methanol, immune-affinity column clean-up, and HPLC system equipped with post-column derivatization method and fluorescence detection were performed for determination of AFB(1)and AFB(1)-Alb levels in the samples. The mean level of dust and AFB(1)in the personal and area air, and in the settled dust and the AFB(1)-Alb in the serum of workers in the bread waste sorting, was higher than plastic waste-sorting samples, in all of the sites. The differences in the biochemical profiles of subjects exposed to aflatoxin B(1)as compared to the control group especially in liver and kidney function parameters as well as antioxidant factors of the serum were significant. The workers in handling of municipal waste may be exposed to potentially hazardous levels of aflatoxin B-1. The adverse effects of AFB(1)on the kidney and liver may be caused by changes in the redox system

Factors Influencing Unsafe Behaviors and Accidents on Construction Sites: A Review

Objective. Construction is a hazardous occupation due to the unique nature of activities involved and the repetitiveness of several field behaviors. The aim of this methodological and theoretical review is to explore the empirical factors influencing unsafe behaviors and accidents on construction sites. Methods. In this work, results and findings from 56 related previous studies were investigated. These studies were categorized based on their design, type, methods of data collection, analytical methods, variables, and key findings. A qualitative content analysis procedure was used to extract variables, themes, and factors. In addition, all studies were reviewed to determine the quality rating and to evaluate the strength of provided evidence. Results. The content analysis identified 8 main categories: (a) society, (b) organization, (c) project management, (d) supervision, (e) contractor, (f) site condition, (g) work group, and (h) individual characteristics. The review highlighted the importance of more distal factors, e.g., society and organization, and project management, that may contribute to reducing the likelihood of unsafe behaviors and accidents through the promotion of site condition and individual features (as proximal factors). Conclusion. Further research is necessary to provide a better understanding of the links between unsafe behavior theories and empirical findings, challenge theoretical assumptions, develop new applied theories, and make stronger recommendations