ABSTRACT
Growth of the plastics industry in recent decades has been dramatic. Poly Vinyl Chloride is one of the most widely used plastics in the world that granules in the thermal process decompose to Vinyl Chloride Monomer and is released in work air environment. This study aimed to evaluate occupational exposure and estimate workers' exposure with vinyl chloride monomer risk. A cross-sectional study of 100 workers at two Plastic factories in Tehran [A, B] was performed. Personal monitoring of workers to Vinyl Chloride Monomer was conducted by Optimized Method No.1007 from NIOSH. Atmospheric conditions, such as temperature, pressure, air velocity, and relative humidity were measured simultaneously along with personal monitoring. Quantitative risk assessment of workers was computed in the form of Standard Mortality Rate and incident rate cancer. Statistical analysis of data was conducted by SPSS version 19. Climatic parameters in the plant A and B for a relative humidity were 43.77 +/- 16.71 and 37.16 +/- 14.45% and temperature 20.95 +/- 3.34 and 21.05 +/- 2.20 degree C, air pressure 87.48 +/- 0.54 and 87.41 +/- 0.64 kPa and air velocity 0.13 +/- 0.08 and 0.10 +/- 0.06 meters per second were measured respectively. Occupational exposure to Vinyl Chloride Monomer plants A and B were 1.01 +/- 0.51 and 0.72 +/- 0.30 as ppm respectively. Quantitative risk of exposed workers based on Standard Mortality Rate was estimated 1.06 +/- 0.03 times of the population without exposure. Incident rate cancer based on accounting measures of integrated risk Information System was calculated per 1000 person exposure population. The correlation of Standard Mortality Rate and the risk of cancer incidence was statistically significant [R[2] :0.88]. Thirty one percent of workers had higher exposure to Vinyl Chloride Monomer than the occupational exposure limits [1 ppm]. In the present workers' exposure in this study is lower than international workforces reported in decades ago, but higher than studies recently published. The results clearly describes occupational hazard of workers in the current Iranian recession situation. The application of control system in the form of engineering control measure, especially in the coming years with projected economic growth, is justified for securing workers health and well-being.
ABSTRACT
The criticality of existing hazards of chemical processes requires that several protection layers to be used against them. In this regard, applied layers efficiency and resistance analysis is a necessity. In this study the level safety of protection layers of a hydrogen production unit, has been evaluated. In order to assess the protection layers the preferred Layers of Protection Analysis method has been used. In this study, events have the severe effect, initiating causes and frequencies, Independent Protection Layers and Probability of Failure on Demand, the total probability of intermediate events and Safety Integrity Level were investigated. Results showed that the essential risk reduction was ranging from 10[-1] to 10[-2] and a Safety Integrity Level 2 was determined as a requirement. The results also specified it was not necessary to carry out a Quantitative Risk Analysis study. The time consuming nature of preferred Layers of Protection Analysis method, dis show the combination of this method by a software tools may result in more efficient method and lead to more speed and precision.
ABSTRACT
Heat stress is one of the main and the most common problems in the work environments. Extreme heat exposure can cause different clinical symptoms, including headache, nausea, vomiting. The aim of this study is to compare the correlation of Wet Bulb Globe Temperature, Physiological Strain Index and Physiological Strain Index based on heart rate heat stress indices with tympanic temperature and heart rate among the workers of a glass factory. This cross- sectional study was conducted in a glass factory located in Tehran. 72 male subjects were participated in the study. Atmospheric parameters including dry temperature, natural wet bulb temperature and globe temperature were measured to determine the heat stress indices. Tympanic temperature and heart beat rates were also measured. The data were statistically analyzed using the Pearson and Spearman correlation as well as the linear regression tests. The correlation between tympanic temperature and heart rate with heat stress indices was significant [p-value<0.05]. The poly-nominal correlation [R[2]] between Wet Bulb Globe Temperature Index with heart rate and tympanic temperature was 0.208 and 0.214 respectively. This correlation between Physiological Strain Index with heart rate and tympanic temperature was 0.423 and 0.701 respectively. The correlation between Physiological strain index based on heart rate with heart rate and tympanic temperature was 0.579 and 0.068 respectively. The Physiological Strain Index heat stress index had higher correlation with measured physiological parameters in this study.
ABSTRACT
Aluminum and in particular its compounds make up a large proportion of the pollutants coming from the aluminum foundry. In several studies conducted on the harmful effects of aluminum in recent decades, it has been identified as a neurotoxic metal. Chronic occupational exposure through inhalation of dust is a common problem in aluminum foundries. Investigation of the exposure of various occupational groups in two aluminum foundry plants to aluminum aerosols. To study the occupational exposure of foundry workers to respirable aerosols of aluminum, personal sampling was conducted from the breathing zone of 63 workers at two foundries in the south of Tehran city following NIOSH method No. 0600. Then samples were treated using NIOSH Institute optimized method No. 7013 and analyzed by high sensitivity graphite atomic absorption.Collected data were analyzed with SPSS V.16 statistical software using an independent sample t-test and ANOVA. The average of aluminum respirable aerosols in A and B factories were 3.21 +/- 2.33 and 3.31 +/- 2.15 mg/m[3] respectively. The one-way ANOVA indicated that occupational exposure among various occupational groups [Similar Exposure Group] in Foundry A had no significant difference [p=0.089], but differences between the exposure of melting and assembling groups in Foundry B are significant [p=0.044]. In general, in exposure frequency to aerosols in aluminum foundries, a significant difference was observed between melting and assembling groups [p=0.005] as well among abrading and assembling groups [p=0.02]. Most of the exposures to aluminum in foundry workers exceeded the current limits given by ACGIH Institute and the Iranian occupational exposure limits. According to the occupational exposure of both foundries and the absence of differences among variables involved in the exposure, the high exposure of melting and abrading groups compared to assembling groups can be attributed to the nature of these units in the production of aluminum aerosols.
ABSTRACT
Eighty five percent of accidents can be attributed to unsafe acts. Eighty five to ninety eight percent of workplace injuries caused by unsafe acts are due to attitude, behavior and culture. Safety climate is a multi-dimensional structure that describes the attitude and the correct priority of the people towards the safety at work. To assess safety climate, a valid and reliable tool is needed. The aim of this study was developing a psychometric questionnaire to assess safety climate in Iran. Using safety literature and other safety climate questionnaire, a 96-item questionnaire was provided. Face validity, content validity ratio and index, construct validity, internal consistency reliability and test-retest reliability were investigated on 550 industrial employees .After validity index survey 43 items questionnaire were obtained. Principal factors were extracted using exploratory factor analysis by Varimax rotation method. To check the reliability of the questionnaire, Cronbach's alpha coefficients and Pearson correlation coefficient was used. For the face validity, CVR [78.5%] and CVI [0.75] related to safety climate designed questionnaire to be acceptable, eleven factors were extracted that covered 58.85 percent of total variance. Cronbach's alpha for most factors more than 0.7 were calculated and Spearman coefficient showed significant correlation between test and retest results. The Safety "Climate Assessment Questionnaire" which has been designed for 43 items and 11 factors has appropriate validity and reliability and can be used to assess the safety climate.
ABSTRACT
A considerable amount of sulfur hexafluoride is applied to evaluate the performance of each laboratory hood according to ASHRAE-110-95 method.SF [6] is extremely hostile to environment and expensive. In present work, the possibility of conducting this method of hood performance test with less volume of SF [6] was investigated. The performance of a laboratory hood was evaluated using ASHRAE110-95 standard method at three different ventilation capacity as well as three different volumetric flow rates of injected SF 6 while a mannequin was located at the front of hood. Face velocity was measured 180 times using a thermal anemometer TA-2 model.Air flow was visualized through injecting low and high volume of smokes at 18 tests. Sulfur hexafluoride was injected at three different volumetric flow rates of 2, 3 and 4 lit / min.The occupational exposure of a hypothetic hood operator was determined 27 times through direct reading. The average and standard deviation of face velocity at hood inlet were 0.42 +/- 0.04, 0.6 +/- 0.07, 0.7 +/- 0.11 m / s respectively, ranging from 0.36-1.1 m / s. the studied hood did not have an acceptable performance when tested with high volumes of smoke, but it did have an acceptable performance while it was tested with low volumes of smoke. The application of ASHRAE 110-95 hood performance test with smaller volume of tracer sulfur hexafluoride gas is not recommended.
ABSTRACT
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
ABSTRACT
The influences of Low Frequency Noise [LFN] on mental performance have been the objectives of many papers in recent years. Many researchers believe that the LFN even at low pressure levels has impacts on mental performance. In the present work the influences of LFN and Reference Noise [RN] at two different sound pressure levels [45 and 65 dBA] on mental performances of college students during solving math problems were studied. Other factors such as annoyance and sensitivity to LFN and hearing status of the participants were also determined. Low Frequency and Reference Noise were generated and verified using cool Edit software program. The number of participants was calculated using data gathered from a pilot study conducted in advance. The mental performance of the students was evaluated while they were exposed to LFN and RN at 45 and 65 dBA sound pressure levels. For this purpose, standard psychological tests were applied. Standard measuring instrumentation including sound level meters, psychological tests, acoustic room and etc were calibrated prior to their application based on standard methods. The results revealed that, Low frequency noise annoyance and sensitivity have no significant differences between different studied ages and sexes. The result also revealed that, a significant correlations exists between sensitivity to low frequency noise and deep mental process [r=0.33, p=0.01]. It was recognized that low frequency nose at 65 dBA can decrease accuracy [p=0.005] and performance [p=0.001] in comparison with reference noise at the same level. Low frequency noise, have impact on mental performance during performing math calculations
Subject(s)
Humans , Task Performance and Analysis , Students/psychology , Educational Measurement , Psychological Tests , Pilot Projects , Environmental Exposure/adverse effectsABSTRACT
Although the asbestos application is band in most developed countries but it is still used in many developing countries, escalating the mortality rate due to cancer among the workers exposed to asbestos fibers. In the present work, occupational exposure to airborne asbestos fibers in production line of an asbestos-cement products manufacturing factory were assessed, using OSHA method ID-160. For this purpose, 106 personal air samples were collected from breathing zones of workers in various processes of the factory. Cancer-related mortalities were also predicted by extrapolation of OSHA risk assessment data to the data obtained from the factory in question. The results revealed that physically disturbing processes such as mills, drilling and cutting are the most deadly processes. It was also shown that mills have the highest mortality rate due to asbestos fibers exposure, expecting 1198 deaths per 100,000 workers after one year exposure and 14665 deaths per 100, 000 workers after 20 years occupational exposure. Relative risk [RR] of lung cancer after 1, 20 and 45 years working in the factory in question versus public community of Iran would be 11.6, 206.5 and 324, respectively. Cancer-related mortality predicted for dry cutting process was more than wet cutting process [RR=3.6]. Finally it was recommended that job rotation and isolation of high risk operations could lead to lower cancer-related mortality due to occupational exposure to asbestos airborne fibers
Subject(s)
Humans , Carcinogens , Lung Neoplasms/etiology , Occupational Exposure , Risk Assessment , Mesothelioma/etiologyABSTRACT
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
Subject(s)
Occupational Exposure , Risk Assessment , Particle Size , Particulate Matter , Air Pollutants , VentilationABSTRACT
Underground railway systems, can generate heat from their operations to raise the temperatures of carriages and the station substantially. This may lead to passenger discomfort and complain especially in warm weather conditions that prevail in Tehran if underground environment is not cooled. Transportation air conditioning Committee of American Society of Heating, Refrigerating and air-conditioning Engineers proposed the Relative Warmth Index for thermal comfort design and investigation in subway environment. In this research, thermal comfort at Tehran metro stations and carriages of lines 1 and 2 has been studied using this index. The measurements were taken during two periods of September 2006 and July 2007 at different zones of stations. For this purpose, temperature, relative humidity and air velocity were measured at different times. The status of the air-conditioning systems together with passenger traffic was also recorded. A total number of 231 measurements including 114 and 117 measurements were carried out in September 2006 and in July 2007 respectively. The measurements in September 2006 did not exceed the thermal limit. However, it did exceed in July 2007. In comparison, with thermal comfort level of metros all over the world, Tehran Metro stands in an acceptable condition, while the maximum capacity of air-conditioning systems was not used, if so the thermal comfort condition would be better
Subject(s)
Humans , Railroads , Models, Biological , Air Conditioning , HumidityABSTRACT
Although the evolution of industrial systems toward digital technologies decreased the exposure to high levels of noise, it has created some problems encountered with low level and provoking noise [low frequency noise]. In the present work, the mental performance of students exposed to low frequency and reference noises at low and high levels [45 and 65 dB] were studied. Additionally, other factors such as annoyance, sensitivity to low frequency noise and hearing status of participants were considered. After generating low frequency and reference noises required for the study, a pilot study was conducted. Then, 54 students participated in the main study after preliminary tests. Their mental performances were evaluated with standard psychological tests while they were exposed to low frequency and reference noises at 45 and 65 dBA. The results showed that noise annoyance and low frequency noise sensitivity do not have a significant correlation with age and sex. The results also revealed that, low frequency noise at 65 dB can decrease concentration [P=0.003] and increase response time [P=0.039] of performance in comparison with low frequency noise at 45 dB. On the other hand, reference noise at 65 dB can increase speed [P<0.001] of performance in comparison with reference noise at 45 dB. Low frequency noise can reduce the mental performance and increase its response time