[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

[Adsorption of reactive red 198 azo dye from aqueous solution onto the waste coagulation sludge of the water treatment plants]

Much attention has been recently paid on using waste materials as adsorbents for removal of contaminants from water and wastewater. A new low cost waste was examined for its capacity to adsorb RR198, an azo reactive model dye, from an aqueous solution. The waste was dried, powdered and characterized before being used as an adsorbent. The effects of pH [3-10], adsorbent dose [0.2-3 g], dye concentration and contact time on the adsorption efficiency were investigated. Equilibrium study data were modeled using Langmuir and Freundlich models. The characterization analysis indicated that it was composed mainly of ferric hydroxide. The powder had a BET and average pore size of 107 m2/g and 4.5 nm, respectively. The results showed that dye removal was highest at a solution pH of 7 to 8 and a powder dose of 2 g/L. The RR198 removal percentage decreased from 100 and to 43% and at 140 min contact time when the concentration of dye was increased from 25 mg/L to 100 mg/L, at optimum pH and dosage. The Langmuir equation provided the best fit for the experimental data. The maximum adsorption capacity was calculated to be 34.4 mg/g. According to the obtained results, the water coagulation waste sludge appears to be a suitable low cost and effcient adsorbent for removing reactive azo dyes from waste streams

[Degradation of transformer oils by photolysis in order to reduce occupational and environmental hazards]

Polychlorinated biphenyls [PCBs] are toxic, persistent, bio-accumulate and pose a risk of causing adverse effects on human health and to the environment. PCB compounds exert varios impacts on human depending upon age, route of entry, intensity and frequency of exposure. This study was conducted to determine the effect of UV-C, hydrogen peroxide and solvent on the photodegradation of PCBs. The photochemical reactor was of annular geometry [500 ml volume] with a cylindrical low-pressure mercury lamp emitting at 254 nm. The power emitted by the lamp was 6 W. The whole lamp was immersed into a reactor with temperature of 32 +/- 2 C. The PCBs were analyzed by GC/ECD equipment. The degradation of total PCBs in terms of one, two and three lamps was 77.5%, 82.9% and 85.2% respectively. The degradation of total PCBs in terms of not using of H[2]O[2] and using 10% and 20% of H[2]O[2] were 74.5%, 79% and 94.5% respectively. The results of this experiments showed that UVC-photolysis of H[2]O[2] leads to a degradation efficiency of PCBs only in the presence of ethanol

[Effect of waste activated sludge pretreatment with ozone on the performance of aerobic digestion process]

A conventional treatment to stabilize the excess activated sludge is the aerobic digestion process but due to long aeration time, it requires large equipments as well as high investment cost. Because of high oxidation potential of ozone, sludge ozonation enhances stabilization rate and reduces sludge treatment equipment size and cost. Therefore, in this study, the combination of pretreatment with ozone and aerobic digestion processes were investigated. The experimental set-up consisted of an ozone generator and ozonation reactor with the total volume of 2 L. Removal percentages of TSS, VS, total and soluble COD, HPC, fecal coliform and settable solids were measured in integrated process compared to the single ones. The results of this research indicated that the aerobic digestion of waste activated sludge during 10 days could reduce 38% of volatile solids and thus obtaining the EPA standard. Also, the results of combined ozonation and aerobic digestion revealed that the pre-ozonation at 0.25 g O3/g TS or 0.5 g O3/g TS with 6 or 3 days aeration, respectively, could achieve 38% reduction in VS and hence the requirement set by EPA. Therefore, integration of pre-ozonation with aerobic digestion can significantly reduce the digestion time to attain the standards. The sludge pre-ozonation with low dose of ozone due to solids disintegration can enhance the efficiency of aerobic digestion in waste activated sludge stabilization, and consequently decrease size of equipments, air requirement, investment and probably operation cost

[Consequence analysis of toxic chemicals release from petrochemical feed and product pipelines network]

Consequence analysis of toxic chemicals releases has important influence on emergency response planning and reduction of fatalities. To determine consequences of toxic chemicals releases in petrochemical feed and product pipelines network. This was a cross-sectional study performed in Mahshahr Petrochemical Special Economic Zone [Petzone, Iran] during 2006-2007. Initially, a total number of 60 pipelines were evaluated using the chemical exposure index and the most hazardous chemicals selected for further analysis. Later, the lethal concentrations of chemicals were calculated by probit equation and local meteorological data assessed. In the end, the toxic release dispersion modeling was performed using of areal location of hazardous atmospheric program, and the fatal length for emergency response planning offered. Butadiene pipeline showed the highest chemical exposure index value however, the chlorine pipeline was found to have the most hazard distance based on life-threatening health effects of emergency response planning guideline [ERPG-3]. The LC1, LC50 and LC99 in F condition were about 703m, 413m and 248m, respectively. Determination of hazard distance and emergency response planning for chlorine pipeline based on LC1 and in F condition will supply the lowest level of fatality and highest margin of safety in areas adjacent to petrochemical feed and product pipelines network

[ effect of microwave radiation on rabbit's hearing]

Regarding the rapid development in technology of mobile communication and increasing growth in number of users, the radiation of these waves has become as one of the concerns of today's society. The aim of this study was to assess the potential changes in auditory system of rabbit following exposure to microwave. This was an experimental study carried out at two auditory centers of Tarbiat Modaress University and Iran University of Medical Sciences in Tehran [Iran] in 2005. White Newsealand male rabbits were the experimental animals used in our study and the Auditory Brainstem Response [ABR] as the method to evaluate the possible changes following exposure to radiation. The latency time of the fifth wave of ABR was measured and recorded pre- and post-exposure using two stimuli [Click and Tone burst] at different frequencies and two intensities of 70 and 100 dB. The latency time of wave V was increased for different frequencies used in our experiment. An increase of more than 0.2 ms was noticed especially at two frequencies of 2000 and 8000 Hz. Statistical analysis of results was indicative of no significant change between latency times of wave V [ms] pre- and post-exposure. The results of audiometry provided evidences regarding the effect of microwave radiation at the levels produced by mobile phones on rabbit's auditory system. Our data suggest the prudent use of mobile phones

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

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

Synthesis, activity and thermal stability of gold nanoparticle on modified NH[4]-Y type zeolite for cooxidation

Gold nanoparticle is the active catalyst for CO oxidation at low temperature. This feature of gold base catalysts is suitable to overcome the problem of cold-start problem of automobile exhaust TWC converters. In this study gold nanoparticle were deposited on modified NH[4]-Y type zeolite. The activity of synthesized catalyst was measured in a fixed-bed quartz-tubular reactor [7mm i.d.] under atmospheric pressure. In order to investigate the catalytic activities toward CO oxidation reaction, 31mL/min of air and 0.155mL/min of carbon monoxide were mixed and then passed through the reactor. It was found that activity of Au/Y catalyst was 100% at 20°C. The thermal stability of Au/Y catalyst was measured at 400°C for 4h. The activity of the catalyst was decreased to 65% at 20°C after thermal stability test. Results of Energy Dispersive Analysis by X-rays before and after thermal stability have showed that Au content of these samples were 3.89% and 1.76, respectively. It was found that the amount of Au content decreased after thermal stability process. Fourier Transform Infrared [FT-IR] spectra showed no changes in framework structure of zeolite during thermal stabilization process of the catalyst

[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

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

Evaluation of 4,4-methylene diphenyl diisocyanate effects on foam producing workers of car manufacture

4, 4 - Methylendiphenyl diisocyanate[MDI], is the most widely used chemical in the manufacturing of polyurethanes [a field of plastic industries], and it is one of the major causes of the occupational asthmas. Assessing the MDI concentration in air and also evaluating the effect of this chemical on eyes, skin, respiratory and gastrointestinal systems in workers of a foam producing section in a car manufacturing company. The effects of MDI on skin, eyes, respiratory and gastrointestinal systems were evaluated in two 40-person groups of exposed and unexposed workers and the MDI concentration in air was determined. The data were analyzed using t-Student test, pair-t-test, lamda[2] test, Regression Analyze, and correlation test. MDI concentration was lower than the threshold limit value while the local ventilation and air conditioning systems were both on, however, it was higher than the expected value when both systems were switched off. Our results showed that the presence of symptoms such as coughing, smart pain and dryness of skin, and the smart pain and itching of eyes in exposed group were significantly different from those in unexposed group[P<0.05]. Some of respiratory volumes were indicative of a significant difference between exposed and unexposed groups [P<0.05]. Exposure to MDI can result in reduction of respiratory volumes while increasing the occurrence of eye, skin and respiratory symptoms

Removal of ammonia from air, using three Iranian natural Zeolites

Ammonia in air can be hazardous to human and animal life and should be removed from the environment. Recently the removal of environmental pollutants such as ammonia by means of natural and modified zeolites has attracted a lot of attention and interests. In this study the capability of three Iranian natural zeolites [Clinoptilolite] in point of view of removal of ammonia from air was investigated. Through this research, different zeolites from various regions of Iran including Semnan, Meyaneh, and Firoozkooh resources were considered to be studied. These samples of zeolites were ground and granulized into 425 microm to 4 mm and were utilized in dynamic sorption experiments. Curves of sorption were plotted and breakthrough and saturated points of zeolite samples were obtained. The adsorption capacities at different ammonia concentrations, temperatures, and flow - rates were also calculated. Results obtained showed that, the natural Iranian zeolite [Clinoptilolite] was identified to be more efficient adsorbent than the others to remove ammonia from the air. In the same conditions, the obtained breakthrough time for clinoptilolite sample of Meyaneh was longer than the others [ 135min ], while, the adsorption capacity of Semnan clinoptilolite was higher than adsorbents [ 6.30 mg /g] [P<0.0001].