دو ماهنامه سلامت کار ایران
سال یازدهم شماره 2 (خرداد و تیر 1393)

In the steel industry, air blowers used to supply compressed air are considered as sources of annoying noise. This study aims to design acoustic room chamber in order to noise control of air blower. Measuring of the noise level along with frequency analysis were performed by using sound level meter model of CASELLA-Cell.450. Dosimetery in order to worker exposure was performed using the dosimeter model TES-1345. Linear sound power level of machine was calculated based on ISO 3746. Distribution of noise emission of the source was shown in form of workroom noise maps using Surfer software. Acoustic analysis of workroom was performed based on sound absorption characteristic of internal surfaces. In order to noise control, an enclosure along with condensed sandwich panels for blower was designed and finally, the effect of this intervention was estimated. The results showed the total sound pressure level of the air blower was 95.4dB (Lin) in which the dominant frequency was 2000 Hz. Moreover, sound power level of the air blower in the dominant frequency was 102.94dB (Lin). The effective absorption surface of workroom was estimated equal to 0.082 and the average occupational noise exposure level based on noise dose was equal to 230%. The designed enclosure along with the steel and fiberglass as a primary insulation layer and punched sheet by steel layer as absorption sound on internal surfaces, actual transmission loss in the dominant frequency, by taking 0.001 opening, was estimated 30dB. gearbox and compressor was the main cause air blower noise that is created Because of the Spiral gearing wheels spinning rotor gearbox parts and the interaction between the rotary and fixed blades move air through the compressor is caused. Enclosure design noise dose received by worker reduced to less than 20 percent. Keywords: module design, air blower, noise control, acrostic analysis, steel industry.

Nowadays, chemical materials are so much useful in our lives. Laboratory technicians expose to different chemicals. Many consequences of chemical exposure are chronic. In this research the risk of occupational exposure to hazardous chemicals in laboratories of educational and therapy centers of Qom University of medical sciences was assessed. The method of this research was derived from Malaysian department of Health and Safety. Preparation of data gathering tools, team member's selection, job analysis, identification hazardous chemical materials, hazard and exposure rate Assessment and finally determination of risks were important steps of this research. Excel 2010 & SPSS16 software was used for data analysis and for determines correlation between parameters used Mann-Whitney, Kruskal - Wallis and chi square tests. There were no hazardous materials in 30% of laboratories. The risk of hazardous chemical exposure in 6.67%, 20% and 43.33% of laboratories respectively were high, moderate and low. In this study exposure to hazardous chemical materials determined 1.205±1.0047 (mean±sd), hazard rating 2.307±1.64 and risk level 1.769±1.22. Because of exposure to Formaldehyde, pathology labs were the most hazardous areas. There was no significant correlation between marital status, job experience, education level and passing work related training and risk (p>0.05). 26.67% of laboratories had considerable risk. In order to risk control elimination, substitution, engineering and administrative control and applying personal protective equipment recommended.

Asbestos components are one of the most hazardous air pollutants that cause different dangerous diseases human. The main goal of this research was assessment of occupational exposure effects with Asbestos fibers on pulmonary function and lung capacity disorders in worker of an Asbestos- cement pipe and plate manufacturing plant. This research is a Cross-sectional study that 78's personal of an Asbestos- cement plant during of 2009-2010 were studied. Required information was collected with complete of respiratory questionary prepared base on standard reference personnel exposed to different concentrations of asbestos fibers. Also to evaluate pulmonary function testing personnel lung spirometry was performed according to the American thoracic society standards and to data Analysis Spss software & chi-square test were used. Subjects had age average and SD of 41/05±5/2, also in this study had been a significant association (P<0/05) between work histories and disorder' pulmonary function and effective of Asbestos on them. Result of spirometry in different parts to low, moderate and high exposure, shown that 72% of workers had normality’s of lung function and 28% of workers abnormalities. Also, Abnormalities of lung function in all studied workers include different restrictive patterns such as severe (2%), moderate (12%) and mild (14%). Base on gained results, there was a significant relationship between decrease of lung capacity and restrictive lung disorders with increase of age and work history in worker to high exposure with Asbestos fibers. Therefore Environmental and Personal Controls consist of: replacing asbestos, training, (P.P.E) and limit of exposure time are needed.

Knowledge of the rate and causes of occupational hazards occurring in hospitals may be effective in formulating policy aimed at prevention as well as reducing their accident and cost. The aim of this study was to investigate the characteristic factors responsible for the occupational hazards occurrences among the employees of teaching hospitals of Qazvin University of Medical Sciences. This study was a descriptive analysis of 258 employees of Qazvin teaching hospitals in 2012.The sample of this study were choosen in a stratified multi- stages method. A researcher-made questionnaire was used for collection of data. The data obtained were analyzed using SPSS software and presented as count, frequency and percentages. Categorical data were analyzed using t- test as well as Anova.The highest level of occupational hazards’ occurrences was due to skin contact with blood or other body fluids while the lowest level was because of assaulting by patients or their families. There was a significant relation between the variables of age, gender, work experience, job title, and marital status as well as the hospital itself and the rate of occupational hazards.)P<0/05).There was no significant relation between the mean duration of absence from work and the rate of occupational hazards. (P>0/05).The most important causes of occupational hazards from the employees ‘viewpoint was the overload of working.From the results of this study, it was found that the major factors influencing occupational Hazards’ development included: overload working, personnel indiscretions as well as working condition. As a result of increasing empolyees proportional to size of activity, employees training regarding occupational characteristics and monitor standard precautions for the prevention of occupational hazards could be responsible.

The correct assessment of volatile organic compounds is a main stage of their control's action plan. Needle trap device (NTD) as a novel technique with all advantages of microextraction methods, is an inexpensive and rapid technique for survey of air pollution agents. In this study the performance of this technique was investigated for sampling and analysis of organohalogen compounds in air. The performances of NTD packed with PDMS foe sampling and analysis of some of organohalogen compounds were investigated. The effects of performance parameters in three stages of sampling (BTV, temperature and RH), sampling storage (storage time) and analysis (desorption time and temperature) were investigated and compared with NIOSH proposed method and SPME with same sorbent. NTD showed better performances in lower temperature and RH and the ability for storage of sampled analytes was more than 95% after 3 days. The optimum desorption temperature and time was 290◦C and 4 min respectively. The relative standard division for investigation of technique's repeatability for 5 NTD with same geometry was obtained 3.4-8.7%. In comparative study, NTD showed better performances in compare with NIOSH proposed method and presented same performances in compare to the SPME coated with similar coating fiber. The NTD-PDMS revealed a good performance for sampling and analysis of volatile organohalogen compounds (HVOCs) in air and we propose this method for air pollution monitoring of indoor and outdoor pollutants.

Subway system including infrastructure systems in the transportation industry that is potentially exposed to fire, flood, earthquake and similar events and could create catastrophic losses to society. Therefore, this study aims to assess the fire risk in Tehran subway stations (line 1). In performing this research, after the identifying the fire hazards resources in subway stations through observing, interviewing techniques and reviewing the documents, using fault tree analysis the causes of electrical fires in rectifier substations in line 1 of Tehran metro, was determined. Further more, with quantitative fault tree analysis, the probability of the fire risk was calculated per year. The findings indicate that, main causes of electrical fires in this post are including signs and devices, improper maintenance, improper implementation during equipment installation, inappropriate quality of equipment and their aging. The probability of an accident every 11 years was calculated. By holding training courses for personnel involved and careful monitoring during maintenance and installation of equipment, much lower probability risk would occur.

The term "crystalline silica", refers to crystallized form of SiO2 and quartz, as the most abundant compound on earth crust, it can causing silicosis and lung cancer at inhalation large doses in course of occupational exposure. Silica exposure is unavoidable during demolition of buildings and therefore it can result in many problems for demolition workers’ health the aim of this study was assessment of workers respiratory exposure with crystalline silica in during demolition of buildings in Tehran. In this study, in order to assessment of airborne crystalline silica exposure, four zone of Tehran (west،east،south،center) selected. Samples were collected on mixed cellulose filters, by using filter holder at flow rate of 2 l/min for a maximum volume of 800 liters. After the transferring the samples to laboratory then in order to analysis of samples, Visible absorption spectrometry (at 420-820nm) was used according to the "National Institute of Occupational Safety and Health" (NIOSH) method No. 7601 higher average of exposure crystalline silica with geometric mean of 0/185 mg/m3 was related to south area، and center area with GM 0/085 mg/m3 have lowest exposure with crystalline silica. 48 sample (80%) of total sample were above the standard for crystalline silica (ACGIH0/05mg/m3). The geometric mean of worker's exposure to crystalline silica was in the range of 0/085-0/0185 mg/m3. regarding to 80% of total of sample was above the threshold limit value (0/05mg/m3). And exposure with crystalline silica during demolition of building unavoidable, this necessitates control of emission of dust during demolition.

Production of fixed concentration of vapors from pure liquid has many applications in laboratory and field studies of occupational health and toxicological research and also in calibration of air pollutant measurement devices of the workplaces. In this study, the advantages and disadvantages of different concentration generation methods were discussed. In addition two methods were compared and the factors that influence the concentration were identified. In order to make certain concentrations of styrene, evaporation and injection methods were used. In evaporation system air was blown in the 250 (ml) midget impinger in two modes (close to the liquid surface and the inside liquid). In injection system a syringe pump (3100 Graseby, Smiths Co) was used. Affecting factors on concentration stability like temperature, flow rate, position of nozzles have been investigated. To produce 300(ppm) of styrene vapor concentrations in RH=19%, coefficient of variation (C.V) of the concentrations generated in bubbler and syringe pump system were 2.86 and 2.01 percent respectively. Syringe pump system reach to equilibrium approximately in 60 (min), while it takes 105 (min) for the evaporative concentration system. When the nozzle of bubbler is placed close to the liquid surface, and when the nozzle is placed inside the liquid, coefficient of variation were 1.97% and 2.52% respectively. Controlling the influencing factors like temperature and flow rate are most important points for generation of constant concentration. The low coefficient of variation in the syringe pump system proved better capability and functionality of this system compared to bubbler system. One advantage of the syringe pump system is that it is not dependent on liquid level of the container.

The construction industry is known as one of the most dangerous industries according to its unique nature. With the rapid development of construction in our country, the safety problems at construction sites have become a serious problem. Therefore, paying attention to safety, identifying its effective indicators and projects’ safety evaluation is known as an essential issue for improving safety performance of construction projects. Regarding the factors influencing site safety which have fuzzy and uncertain nature, grey fuzzy analysis has been used in evaluating model. Grey theory which is one of the multi-criteria decision-making methods is used to solve problems with discrete, vague and incomplete data. Also Analytic Hierarchy Process (AHP) is used to determine weight of each index. In three different construction projects which are analyzed as case studies, the indicators affecting construction safety are identified and the site safety setting is studied. According to the results, enough equipment and preventive actions index obtained the highest weight (0.307) and the least weight was for proper signage (0.018). Then, using grey fuzzy method, the current safety setting in the three sites is evaluated and ranked. The safety setting of project 1 was more appropriate. Comparing the results with the past research, experimental observations and feedback from risk assessment group demonstrate that this method is reliable and useful; therefore, it is recommended that safety managers use this method and also use factors identified in this study for safety performance assessment and reducing construction projects accidents.

Background of During physical activity in hot environments, sweating along with evaporation increased, as the most important physiological response, which can lead to dehydration. The aim of this study was to investigate the variation of urine density in dehydration conditions of workers in hot workplaces. In this cross-sectional study, 40 workers in the hot environments were selected as case group and 20 administrative staffs as control group. In order to assess dehydration level in the employees, urinary density was measured at the beginning and end of shifts using hand hold model of Refractometer (density gauge device). In order to evaluation heat stress in workstations, heat stress index was measured using a digital WBGT meter manufactured by Casella. Ultimately, data obtained from this study analyzed using compare means and Cochran tests by SPSS 16 software. In most of the workstations, heat stress index was higher than the national recommended limit; while this index in the control group was lower than the mentioned limit. Based on compare means test, the urine density of the case group at the beginning and end of their shift showed a significant different (p<0.001). In addition, Based on compare means test, the urine density of the case group was higher than the control group at the end of work shift (p <0.01). The level of urine density with regard to the effects of confounding factors could suitably show the levels of dehydration of workers exposed to heat. Therefore, the density of urine can be used as an acceptable biomarker for evaluating the occupational exposure to heat in order to determine the risk of inducing the heat strain.