Journal of Health and Safety at Work

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Introduction: Risk assessment of Toxic or hazardous chemicals enables the Industrial Hygienists to make the appropriate decision in providing healthy work place. This project was conducted in an assembling plant,(4workshop) of an Automobile Industry in IRAN with 2 types of welding operations, including GMAW (CO2 welding) and Spot resistance welding operations.

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Method and Materials: Welders` exposures were assessed via collecting 143 breathing zone air samples based on NIOSH 0500 method. Risk assessment was carried out using Singapore recommended method.

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Results: Finding showed that the mean of welders exposure in GMAW and Spot resistance welding operations 5.61 ± 5.78and 2.38± 2.15 mg/m3, respectively(p<0.05). The results showed that in GMAW welders had the highe exposure in comparison with Spot resistance welders (p<0.05). The findings also demonstrated that the risk rate of GMAW welders were high, while this rate for Spot resistance was low.

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Conclusion: more hygienic attention is needed for GTAW welders. Control approaches are required including effective engineering control, conduct air monitoring, biological monitoring training, adopt respiratory protection program, develop and implement safe and correct work procedures and finally reassess the risk after all the controls have been done.

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Bazaars are most active and comprehensive center of urban life in Iran and according to its nature, have the economic and social functions. The nature and severity of risks associated with the quantity and quality of materials and enrgy available has led the growing importance of preventive safety assessment in Bazaars. The main objective of this study is to provide a model for risk assessment and management in urban Bazaars. After familiar with the studied systems, interviews with experts, using the Delphi method and paired comparisons, framwork of risk assessment and management was designed.The framework was tested and verified in Hamadan Bazaars. Results showed that the total risk of Hamadan Bazaars, 20.5% of zones in high risk area, and 79.5% were in cautious area. Using of 22 parameters to determine Bazaar zone risks and focus on total, preventive, detective and control risk was the strenght of this study.

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The safety of high risk jobs especially in oil refining activities is a major concern. In the present paper, the welding risks in Tehran oil refinery have been assessed using the Job Safety Analysis (JSA) and the effectiveness of the controlling methods have been investigated. A descriptive study was conducted on 33 risks of 10 welding tasks in Tehran oil refinery (north unit). After arranging the appropriate expertise team, tasks in the welding process were identified using two methods of viewing the process and interviewing with the welders. The risks of each task were then identified through viewing the process, interviewing the welders and completing safety checklists. Risk Priority Number (RPN) was used for risk assessment. RPN was estimated from Likelihood and Severity Numbers using Australia/New Zealand standard (AS/NZS 4360/2004). Risk assessment was conducted for existing and post-control conditions. The effectiveness of the controlling measures suggested by the expertise team was evaluated using appropriate statistical methods. The results revealed that in the existing condition, 27.3% of the studied risks have a RPN of 5 (with an extremely high hazard potential), 3% a RPN of 4 (with a high hazard potential) and 69.7% with a RPN of 3 (with a medium hazard potential). The results also revealed that with the application of control measures suggested by the expertise team, 21.2% of the studied risks will hold a RPN of 4 (with a high hazard potential), 6.1% will have a RPN of 3 (with a medium hazard potential), 48.5% with a RPN of 2 (with low hazard potential) and 18.2% will have a RPN of 1 (with a negligible hazard potential). Statistical tests revealed that the application of control measures, will reduce the average amount of likelihood, severity and risk priority numbers significantly (Pvalue<0.01).

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Introduction: In addition to direct and indirect costs of occupational accidents imposing on production companies, they impact the productivity of labor, too. However, gaining more profits and having less costs is always the main concern among industrial managers. Considering safety measures can be effective way to reduce occupational accidents and costs as well as negative impacts on production systems.

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Material and Method: In this paper, a risk assessment method using fuzzy and MATLAB software is presented to determine the safety level of production environments. The main parameters of this model include three items: accident probability, accident severity and current safety level. For this purpose, the statistical data of accidents and their causes published by Social Insurance Organization have been used in this study. Furthermore, expert judgments of safety and health professional have been used to determine the severity of accidents. In the fuzzy method, the Mamdani deductive fuzzy model has been adapted due to its easy applicability. Application of the model has been shown using a practical instance.

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Result: The defuzzified value for RL is found to be 3.48. Linguistic risk level expression is 100% substantial high risk that is full membership for fuzzy average set.

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Conclusion: The application of the proposed method can reveal which safety items and factors are most important in improving workers safety, and therefore decide where to concentrate resources in order to improve the safety of the work environment.

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Introduction: ”Exposing to danger” or in other words, “risk” is a process which is led to an uncertain result in every field. Project risks are uncertain contingent events or situations that if they occur will have positive or negative effects on project’s objectives. Todays, research and educational process and more complicated and the professional risk management become much more difficult, as a result.

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Material and Method: In this research, the health and safety issues have been studied and analyzed using ISO 14121 and the environmental issues by EMEA to determine the risk level separately for research laboratories and to prioritize corrective measure in each field (school).

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Result: The finding in this study showed that from all the main risks within the rage of 38-86 percent have been decreased. Moreover average of the risk level for the health, safety and environment cases showed a significant decrease (Pvalue<0.0001) by implement controlling and protective countermeasures compariy to the priority state without any measures.

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Conclusion: The risk assessment with hazards control strategy based on ISO 14121 is a compatible method in laboratory site as universities and other reasearch sites.

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Introduction: Every year thousands of people in Iran loss their lives in traffic accidents. Any those accidents, motorcycle accidents are fatal. Safety attitude is a predictor of risky behavior. The purpose of this study was to investigate the relationship between personality, attitudes to safety and risky behaviors.

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Material and Method: In this study 254 motorcycle drivers were randomly selected in Tehran city, and they were asked to complete personality, the attitude to safety and risky behaviors questionnaire.

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Result: A statistically significant correlation was found between different domains of personality (fear, anger, Emotional styles, altruism, anomaly) and attitude to safety (traffic flow in obedience to the law, driving speed, driving excitement), (P = 0/001). Also between personality and attitude to safety the relationship was statistically significant (p = 0/001).

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Conclusion: Attitude to safety is a predictor for risky behavior. Personality also the impact indirectly on the attitude to safety have and risky behaviors.

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Introduction: Due to the increasing population and the need for setting in cities, we witness an increase in high-rise building in Iran. Moreover, because of the ambiguity and complexity, they have various risks potential. Health problems are among this risks for the residents. These risks have short term or long term effects,which can cause illness or even death.

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Material and Method: In the present study, health risks in high-rise buildings are identified, assessed and ranked. Health issue are identified by conducting interview with experts in high-rise building an using specific health and safety related checklists. Due to ambiguous nature of risks and existence of uncertainly, fuzzy logic technique with trapezoidal distribution was used for quantification. Finally, after risk evaluation and calculation of critical degree of each risk, the risks were ranked.

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Result: Risk factors obtained over 0.5 for most of the risks that indicate the importance of Health in high-rise projects during construction phase. The results also showed that the health risks should be assessed before the start of the project in order to reduce or eliminate their impacts.

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Conclusion: Safety risks in High-rise Building projects is very important. These risks have many impacts directly and indirectly on the time, quality and costs of projects. Therefore, evaluating and controlling each health risk in the design and implementation phases are essential. Most of the risks factors identified in this study, can be prevented by using personal protective equipment. The role of the training people involved in this projects are essential to use personal protective equipment.

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Introduction: Process industries, often work with hazardous and operational chemical units with high temperature and pressure conditions, such as reactors and storage tanks. Thus, probabilities of incidence such as explosions, and fire are extremely high, The purpose of this study was to present a comprehensive and efficient method for the quantitative risk assessment of fire and explosion in the process units.

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Material and Method: The proposed method in this study is known as the QRA and includes seven steps. After determination of study objectives and perfect identification of study process, first, qualitative methods are used to screen and identify hazard points and the possible scenarios appropriate are identified and prioritized. Then, estimation of frequency rate are done using past records and statistics or Fault Tree Analysis along whit Event Tree. PAHST professional software and probit equations are used in order to consequence modeling and consequence evaluation, respectively. In the last step by combination of consequence and frequency of each scenario, individual and social risk and overall risk of process or under study unit was calculated.

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Result: Applying the proposed method showed that the jet fire, flash fire and explosion are most dangerous consequence of hydrogen generation unit. Results showed that social risk of the both fire and explosion caused by full bore rupture in Desulphrizing reactor (Scenari3), Reformer (scenario 9) and Hydrogen purification absorbers are unacceptable. All of the hydrogen generation unit fall in ARARP zone of fire individual risk (FIR) and FIR up to 160 m of boundary limit unit is unacceptable. This distance is not only beyond of hydrogen generation unit boundary limit, but also beyond of complex boundary limit. Desulphurization Reactor (75%) and Reformer (34%) had the highest role in explosion individual risk in the control room and their risks are unacceptable.

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Conclusion: Since the proposed method is applicable in all phases of process or system design, and estimates the risk of fire and explosion by a quantitative, comprehensive and mathematical-based equations approach. It can be used as an alternative method instead of qualitative and semi quantitative methods.

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Introduction: Due to the presence of extreme hazard sources and high intrinsic risk in refineries and process industry sectors, different layers of protection are being used to reduce the risk and avoid the hazardous events. Determining Safety Integrity Levels (SILs) in Safety Instrumented Systems (SISs) helps to ensure the safety of the whole process. Risk Graph is one of the most popular and cost effective techniques to do so. Despite Risk Graph simplicity it’s a qualitative method which is highly subjective and suffers from interpretation problems that can lead to inconsistent or conservative SILs.

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Material and Method: In this paper, Improved Risk Graph (IRG) method was presented and evaluated, and using Fuzzy Logic a novel approach namely Fuzzy Improved Risk Graph (FIRG) was suggested. In the proposed method consequence levels which were defined as qualitative terms were transformed into quantitative intervals. Having those numerical values, risk graph table was converted to a quantitative one. Finally, applying the presented approach and using three experts’ opinions and attributing weight factors, an ultimate numeric value was produced.

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Conclusion: as a result of establishing the presented method, identical levels in conventional risk graph table are replaced with different sublevels that not only increases the accuracy in determining the SIL, but also elucidates the effective factor in improving the safety level and consequently saves time and cost significantly. The proposed technique has been employed to develop the SIL of Tehran Refinery ISOMAX Center. IRG and FIRG results have been compared to clarify the efficacy and importance of the proposed method

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Introduction: Every year many people around the world lose their lives or suffer from injuries and serious damages in industrial fire. This study aims at evaluating fire risk using an suitable method and determining endangered humane, financial and environmental capitals in various parts of a chemical industries.

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Material and Method: In this analytical study the developed Frank and Morgan method was used to evaluate the risk of fire in all units of a chemical company. Improved checklists validity was confirmed by experts and then, its reliability was determined by test-retest analyzing method. Human, financial and environmental probable losses were calculated in the case of fire. A risk factor was determined for each unit and all of them were prioritized accordingly.

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Result: The study of developed checklists’ validity showed that there was a high conformity (homogeneity) between results of two measured loads (ICC=0.87 %95CI: 0.699-0.952). Mean value of risk in units was 115.45 and research and development (R&D) and sparse part store units have the highest and lowest risk values, respectively. Endangered humane, financial and environmental capitals had the highest to lowest score, respectively.

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Conclusion: Results showed that the developed Frank and Morgan method can be a suitable tool for evaluating industrial fire risk and prioritizing units in general level of an industrial complex especially chemicals company. According to the findings in this study, the investigation of likely damages to environment in the case of fire has high importance.

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Introduction: One of the most important threats for employees working in chemical industries is exposing to the chemical materials. Lack of precaution and control regulations during working with chemicals can have irreparable consequences. So, in order to achieve an effective control program, it is necessary to have an appropriate assessment of the procedures involving exposure to the chemicals. William-fine method can provide an acceptable insight into hazard risk rate.

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Material and Method: In this study, a combination of AHP and William-fine adopted to achieve a model for chemicals exposure risk assessment in oil and gas industry. The numbers were extracted from questionnaire, and then, they weighted entered to assessment the model. Finally, they were presented quantitatively with protection layer.

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Result and Conclusion: The results revealed that the quantitative amount of consequence, probability and exposure was 83.2, 8.45, and 2.2, respectively. Generally, the chemical exposure risk number was 1546 which shows that reforming plans are in highly priorities from an economical point of view. William-fine method has the benefit of an accurate chemical exposure by combination of effect severity, exposure probability and detriment rate, and also minimization of personal judgments during the assessment.

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Introduction: In the process industries, especially industries with hydrocarbons uses, due to flammability and reactivity of materials, high temperature, operation pressure, volatility and evaporability of liquid, fire and explosion hazard always has a great significances.The purpose of this study was to assess the quantitative fire safety using DOW’s fire and explosion index, in an oil extraction industry.

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Material and Method: The required information for conducting this research was obtained from process documents, DOW’s fire and explosion guideline,the measured operational parameters and also interviews and consultation with the supervisors and experts. Following, the study was conducted in three phases: 1) determination of DOW index, the radius and area of contact, 2) determination of loss control credit factor and finally 3) loss estimation.

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Result: Fire and explosion index in the understudy process unit was calculated 243.68 and thus severity of risk was extremely high and unacceptable. Radius of exposure and loss control credit factor wasobtained62.38 meters and 0.69, respectively. Finally,the most probable loss was estimated about 2863500 dollars.

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Conclusion: DOW’s fire and explosion index is a suitable technique to measure the fire risk of whole plant or a part of it. Thus, this criterion can be used to propose the changes or amount of protective equipment according to their effect in reducing the losses.

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Background: High prevalence of musculoskeletal disorders have been reported by office workers due to the nature of their work. This study aimed to evaluate the prevalence of musculoskeletal disorders in a group of office workers and also to determine the ergonomics risk factors affecting these disorders.
 

Methods: This is a cross-sectional study, performed among 174 office workers in Kerman city, Iran. Data collection tools included demographic and organization information form, the Nordic Musculoskeletal Questinnaire (NMQ), and the Rapid Office Strain Assessment (ROSA) method. The gathered data were analyzed by SPSS software version 16 using descriptive statistics, chi-square test, and logistic regression.
 

Findings: The prevalence of symptoms of musculoskeletal disorders (MSDs) in the past 12 months was reported 60.4 percent. What is more, significant associations were observed between job tenure and hours a day using computer with MSDs (P-value<0.05). In this sense, with  one unit increase in job tenure (years) and duration of computer use (hours per day), the probability of incidence of MSDs gone up 17.2 percent and 15.8 percent, respectively. Based on the statistical chi-square test, a significant relationship was reported between the incidence of MSDs and Rapid Office Strain Assessment method (P-value<0.05).
 

Conclution: According to results, ROSA assessment method is an efficient tool in the classification and identification of factors affecting the incidence of MSDs among office workers. Performing corrective measures in the dangerous work stations (the second level identified by ROSA technique), reducing the duration of computer use per day, and doing regular sport activities can be noted in order to decrease the prevalence of MSDs in the study group (office workers).

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Introduction: Electrical industries are among high risk industries. The present study aimed to assess safety risk in electricity distribution processes using  ET&BA technique and also to compare with both VIKOR & TOPSIS methods in fuzzy environments.
 

Material and Methods: The present research is a descriptive study and ET&BA worksheet is the main data collection tool. Both Fuzzy TOPSIS and Fuzzy VIKOR methods were used for the worksheet analysis.
 

Result: Findings revealed that overhead low and medium voltage power distribution networks had the highest risk among the other network types of transmission and distribution of electricity. Also, it was found that TOPSIS and VIKOR methods are appropriate to rank the safety risks with somehow similar results.
 

Conclusion: The height and electricity are of the main causes of accidents in electricity transmission and distribution industry which caused the overhead power networks to be ranked as high risk. Application of decision-making models in fuzzy environment minimizes the judgment of assessors in the risk assessment process.

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Introduction: Leakage from process equipment and the entrance of flammable fluids to surrounding atmosphere may cause flammable gas cloud. The coincidence of flammable gas cloud with ignition source could make flash fire or vapor cloud explosion that cause injury and fatality. The concept of reduction of confluence of flammable gas cloud and potential sources of ignition is known as hazardous area classification. Several standards have provided methods regarding hazardous area classification; however, of the disadvantages of them are lack of an accurate determination of hazardous areas due to potential leakage sources which is because of low flexibility in process condition variation and equipment layout and also not considering effect of weather conditions and cumulative effects of release sources.
 

Method: In this paper, risk-based hazardous area classification is optimized using parameters such as the number of influencing release sources and weather condition probabilities. In this method, the determining factor of hazardous area boundary is the probability of acceptable ignition for every specific location. This probability is calculated using quantitative risk assessment with PHAST RISK software version 6.7 on the gas boosting unit of a gas refinery as a case study.
 

Result: The results of this method showed the full dependency of hazardous area boundary to cumulative effects of potential sources of release and the prevailing wind direction and it also demonstrated that the suggested optimized method can consider wind direction probabilities and cumulative effects of potential sources of release in risk-based hazardous area classification calculation.
 

Conclusion: Comparing the results of this method with the usual method determines that this method has some advantages such as considering all sources of release and cumulative sources of release and considering wind direction probabilities in determining boundary of zone 2 which makes the hazardous area classification very precise and flexible.

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Introduction: Although human industrial activities are as a part of efforts to achieve greater prosperity, the risks related to these activities are also expanding. Hazard identification and risk assessment in the oil and gas industries are essential to reduce the frequency and severity of accidents and minimize damage to people and property before their occurrence. The aim of this study was to evaluate the liquefied and pressurized petroleum gas spherical tanks in a refinery and assessing the risks of Boiling Liquid Expanding Vapor Explosion (BLEVE) phenomenon.

Material and Method: In this study, the risks of BLEVE phenomenon were assessed, using the Bowtie method. The consequences of explosion wave phenomenon and the resulting wave quantity and its impacts on the neighboring machineries and equipment were analyzed. PHAST software version 6.54 has been used for modeling the BLEVE phenomenon.

Result: In this evaluation, generally five causes and two consequences were identified for BLEVE phenomenon. In order to reduce its consequences, forty-three controlling measures were introduced to prevent the BLEVE phenomenon and the impacts of 31 control measures were identified. According to the conducted analysis, it was found that the spherical tank blast wave caused by LPG can lead to explosion of close located tanks which can create a chain of explosions.

Conclusion: The results of modeling and risk assessment can be used to identify the BLEVE phenomenon causes and its effects on nearby people and equipment. Based on these results, preventive controlling measures can be implemented and also be determined by adopting proper design and layout, margin of safety for personnel, equipment and accessories.

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Introduction: Limited studies have been done to evaluate the whole-body vibration (WBV) exposure experienced by Taxi drivers. Therefore, the aim of this study was to evaluate the exposure to whole body vibration and repeated shocks in urban taxi drivers and also to compare different methods of evaluation in this job environment.

Material and Method: Measurement and evaluation process were conducted in accordance with procedure of the ISO 2631-1 and ISO 2631-5 standards. The measurements were done by SVAN 958 Sound and Vibration Analyzer and using tri-axial accelerometer centered on the contact surface between the seat and the driver in 9 taxis.  

Result: The measurements done according to ISO 2631-1 method showed greater risk compared to Daily Equivalent Static Compression Dose, Sed, presented in ISO 2631-5. Calculated daily exposure durations for exposure action level in root-mean square, vibration dose value, and daily equivalent static compressive stress methods were 4.55, 3.54 and 31.70 hours, respectively.

Conclusion: The large differences in estimated exposure durations of action limits and permissible limits resulted by different methods reflect the inconsistency of the selected evaluation methods. Therefore, future research is necessary to amend the limits presented in the standard.

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Introduction: Occupational exposure to crystalline silica increases the risk of lung cancer and restrictive lung disease with extensive fibrosis. Silica dust is a major health hazard in foundry factories. The aim of this study was to determine core making workers’ exposure to respirable crystalline silica dust in a foundry factory.

Material and Method: This cross-sectional study was conducted in core-making unit of a foundry factory in 2015. Occupational exposure of 55 workers to respirable crystalline silica aerosols was evaluated by using the improved NIOSH7602 method in core-making unit. Risk assessments for silicosis and excess lifetime risk of mortality from lung cancer were done according to Manettej and Rice models, respectively. Data was analyzed with Spss19 software.

Result: The mean of respirable crystalline silica dust was 0.246 ± 0.351 (mg/m3). All  workers’ exposure to respirable crystalline silica was higher than recommended occupational exposure limits. Silicosis mortality risk and excess lifetime risk of mortality from lung cancer were estimated in the range of 6-63 and 65 per thousand people, respectively.

Conclusion: The mean of workers’ exposure to respirable crystalline silica was higher than recommended occupational exposure standards in core making unit. The risk assessment of silicosis mortality and excess lifetime risk of mortality from lung cancer were higher than acceptable levels of risk.

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Introduction: Exposure to crystalline silica dust can seriously threaten health of workers engaged in processes such as casting, stone crushing, grinding, construction activities, insulator manufacturing, and glassblowing and sandblasting. The aim of this study was to assess occupational exposure to crystalline silica and to determine the risk of mortality from silicosis and lung cancer in an insulator manufacturer.

Material and Method: Air personal sampling was performed using 10 mm nylon cyclone and mixed cellulose ester (MCE) membrane filters (5 mm diameter, 0.8 μm pore size) for 60 male workers. Samples were prepared and analyzed according to the National Institute for Occupational Safety and Health (NIOSH) 7601 standard method. The risk assessment of mortality due to silicosis resulting from crystalline silica exposure was done by using model of Mannetje et al. for the period of 10 years. The mortality rate of lung cancer was determined using a linear regression model derived from the study Rice et al.  

Result: The highest and lowest exposure levels to silica were belonged to the packing unit (0.54±0.28 mg/m3) and the furnace (0.02±0.01 mg/m3), respectively. Crystalline silica concentrations for all samples were higher than Threshold Limit Values (0.025 mg/m3) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). According to Mannetje et al. model, the cumulative exposure of 25% workers was in the range 0 to 0.99 that it represents 1 death per 1,000 people. The risk of mortality due to lung cancer was obtained in the range of 7-94 persons per 1000 workers exposed to silica.

Conclusion: In general, the geometric and arithmetic mean of crystalline silica exposure was higher than threshold limit value for most of the subjects. For all workers of the insulator manufacturer, the risk of silicosis related mortality was higher than 1/1,000 (unacceptable level of risk). Predicting the lung cancer mortality from silica exposure indicated a high level of mortality risk among understudied workers.

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Introduction: In recent years, many national and international expert groups have considered specific improvements in risk assessment of chemical pollutants. This study considered to assess the risk of workers exposure to air pollutants in an automobile manufacturing in order to evaluate the health risk assessment due to the inhalation exposure.  

Material and Method: To perform this study, a cross-sectional research was done in 2016. Methods number 1501 and 7602 of the National Institute of occupational safety and Health (NIOSH) were used for sampling and analysis of compounds BTEX and silica in the air. A total of 40 samples of compound BTEX were taken and analyzed by Gas Chromatography-Flame Ionization Detector (GC-FID). A total of 6 samples of silica were collected during the campaign. Silica analyses were performed by using visible spectrophotometry. Risk ranking was calculated using the hazard and exposure rate. Finally, the relative risk of blood cancer caused by exposure to benzene was estimated.   

Result: The result demonstrated that, workers were exposed to 5 chemicals including silica, benzene, toluene, ethyl-benzene, and xylene during their work in manufactory. Among the pollutants in the breathing zone of workers, Silica and benzene were hazardous chemicals at high risk level. Following the estimation of relative risk of blood cancer caused by exposure to benzene, workers cumulative exposure to benzene was obtained to be 23.1 ppm per year and the capture relative risk was 1.1. The consequence demonstrated that, significant relationships were seen between workers exposure to benzene and both age and work experience, so that degree of exposure decreased steadily with increasing age and experience (P<0.001).

Conclusion: This research demonstrated that, benzene and silica in the automobile manufacturing were the highest risk. Also, painting hall workers, at automobile manufacturing, were directly exposed to the blood cancer risk of benzene.