Journal of Health and Safety at Work

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.

Introduction: In developing countries, promotion of road safety is of crucial importance. This paper presents the status of road safety in Iran during 2001 - 2006.

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Material and Method: The status of road safety in Iran was surveyed in this descriptive study using road safety indicators a in macro level. Firstly, 46 indicators were identified after studying almost all indicators related to the road safety. After consulting of views with road safety experts and considering the reliable existing data, 11 indicators were selected to study the safety status of the roads. Then, all essential data for determining each indicators were collected from related organizations and institutes. All indicators were determined and evaluated in the last step.

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Result: The results revealed that during the period of 6 years, death toll has been increased by 9 deaths per 100000 person of the population. Moreover, application of seat belt and safety helmet has been increased by 20% and 18%, respectively. It also indicated that the number of motorists and the length of paved roads have been increased by 20%, and 10%, respectively. The net income per capita has also grown from 5884 US$ to 7968 US$ and the life expectancy has gone up from 68.9 years to 70.9 years, the percentage of the literate population has grown by 2% (from 76% to 78%) and the human development index has increased from 0.721 to 0.759. The results of the present study showed that the increased level of death toll per 10000 vehicles and the increased level (%) of seat belt as well as helmet application, paved roads, urbanization, the net income per capita, life expectancy, literacy and human development index were statistically significant and R2 coefficient for this factors was 0.84, 0.9, 0.994, 0.9, 0.97, 0.82, 0.69 and 0.84 respectively.

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Conclusion: According to result of the present study, roads safety were not in an appropriate level. The roads safety status can be determined using road safety indicators to be applied for road safety promotion.

Introduction: In the most industrial environment, workers are exposed to noise everyday. Exposure to this physical hazardous agent can cause immediate as well as delayed adverse effects. Cognitive performance decrement is one of the adverse effects of noise exposure which its main consequences is occupational accidents. This study attempted examine the effect of exposure to different levels of noise with harmonic indices of neutral, treble and bass on the cognitive performance.

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Material and Method: In this analytical-descriptive study, the cognitive tests were performed by 33 students, aged 23-35 years. During the tests, participants were exposed to three type of noise including neutral, treble and bass at 4 different levels of 45, 75, 85 and 95 decibels. In order to assess students cognitive performance, continuous performance test (CTP) software was employed, which investigated attrition and reaction time.

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Result: The results of this study revealed that exposure to neutral noises with Noise Harmonic Index (NHI) of +3dB at the frequency of 1000 Hz, the maximum percentage of attention (99.88 %) was belonged to Sound Pressure Level (SPL) of 95 decibels. Maximum percentage of attention due to exposure to the treble noise with NIH -105 dB at the noise frequency of 8000 Hz (100%) and bass noise with NIH of 407 dB at the frequency of 500 Hz (99.92%) were belonged to the SPL of 95 and 85 dBA, respectively. Moreover, the result showed that the effect of bass noise with NIH of 4.5 dB and frequency of 500 Hz on reduction of attention were more than treble noise with NIH of -105 dB and frequency of 8000 Hz. Under exposure to neutral noise with NIH of 3 dB and frequency of 1000 Hz, the longest reaction time (2.594 Second) was observed at the SPL of 85 dBA. The longest reaction time for treble noise with NIH of -105 dB and frequency of 8000 Hz (2.786 Second) and for the bass noises with NIH of 4.5 dB and frequency of 500 Hz (2.594 Second) were also belonged to the SPL of 85 and 75 dBA, respectively.

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Conclusion: The results showed that bass noises (frequency of 500 Hz) increased reaction time, in comparison with treble noises (frequency of 8000 Hz).

Introduction: Volatile organic compounds such as xylene are one of the main air pollutants. Adsorption method are of the most common methods used in the control of volatile organic compounds. The aim of this study was to investigate the xylene removal from air through nano activated carbon adsorbent in comparison with NIOSH approved carbon adsorbent.
 

Material and Method: Xylene adsorption tests on nano activated carbon and activated carbon in static mode (batch) were done in glass vials with volume of 10 ml. Gas chromatography with FID detector was used for analysis. Various variables including contact time, amount of adsorbent, concentration of xylene, and temperature were studied.
 

Results: Absorption capacity of xylene at ambient temperature (25° C) in static mode and duration of 10 minutes for activated carbon and nano activated carbon was obtained 349.8 and 435 mg/g, respectively. Results of Scanning Electron Microscope (SEM) images of nano activated carbon showed particle size pf less than 100 nm. Furthermore, Transmission Electron Microscope (TEM) pictures showed particle size of 30 nm. XRD images also showed cube structure of nano activated carbon adsorbent.
 

Conclusion: The results showed that adsorption capacity at constant humidity increased by raising in temperature and contact time. What is more, nano activated carbon absorbent showed greater absorption capacity for xylene removal compared to activated carbon absorbent

Introduction: Volatile organic compounds from industrial activities are one of the most important pollutants released into the air and have adverse effects on human and environment. Therefore, they should be removed before releasing into atmosphere. The aim of the study was to evaluate xylene removal from air by nano-grapheme and nano-graphene oxide in comparison with activated carbon adsorbent.

Material and Method:  After preparing adsorbents of activated carbon, nano-graphene, and nano-graphene oxide, experiments adsorption capacity in static mode (Batch) were carried out in a glass vial. Some variables including contact time, the amount of adsorbent, the concentration of xylene, and the temperature were studied. Langmuir absorption isotherms were used in order to study the adsorption capacity of xylene on adsorbents. Moreover, sample analysis was done by gas chromatography with Flame Ionization Detector (GC-FID).

Results: The adsorption capacities of activated carbon, nano-graphene oxide and nano-graphene for removal of xylene were obtained 349.8, 14.5, and 490 mg/g, respectively. The results of Scanning Electron Microscope (SEM) for nano-graphene and nano-graphene oxide showed particle size of less than 100 nm. While, the results of Transmission Electron Microscope (TEM) showed particle size of 45nm for nano-graphene and 65 nm for nano-graphene oxide. Also, X-Ray Diffraction (XRD) showed cube structure of nano-adsorbents.

Conclusion: In constant humidity, increase in exposure time and temperature caused an increase in the adsorption capacity. The results revealed greater adsorption capacity of xylene removal for nano-graphene compared to the activated carbon, and nano-graphene oxide.

Introduction: Due to the importance of engineering controls for prevention of microwave exposure, this study was conducted to design and constract a novel electromagnetic shielding and also to examine the factors influencing shielding efficacy in X band frequency range.

Material and Method: This study used Resin Epoxy as matrix and nano-Nickel Oxide as filler to prepare the composite plates with three different thicknesses (2,4, and 6 mm) and four different weight percentages (5,7,9 and 11). The fabricated composites characterized using X-ray diffraction and Field Emission Scanning Electron microscopy. Shielding effectiveness, percolation depth, and percolation threshold were measured using Vector Network Analyzers. Thermal Gravimetric Analysis was conducted to study the temperature influence on weight loss for fabricated composites.

Result: A maximum shielding effectiveness value of 84.18% was obtained for the 11%-6mm composite at 8.01 GHz and the 7%-4mm composite exhibits a higher average of shielding effectiveness of 66.72% at X- band frequency range. The 4mm thickness was optimum and critical diameter for composite plates; and percolation depth was obtained greater than thickness of composites. However, increasing the nickel oxide content did not show noticeable effect on the shielding effectiveness. Thermal Gravimetric Analysis showed that the study shields were resistant to temperature up to 150 °C without experiencing weight loss. What is more, the results indicated that Nickel oxide Nano particles had desirable distribution and dispersion in epoxy matrix and percolation threshold was appeared in low content of nickel oxide nanoparticles.

Conclusion: A novel electromagnetic shield using low thickness and few content of nanoparticle with noticeable efficacy was properly designed and constructed in the field of occupational health. In addition, this shield has low cost, easy to manufacture, resistance to wet/corrosion, and low weight. Epoxy/nickel oxide composite can represents a new generation of electromagnetic shielding, which is considered as a promising candidate for occupational protection against microwave exposure. It is recommended that future studies improve the shielding effectiveness by decreasing the percolation depth and investigate the efficacy of the fabricated shield in the workplaces.

Introduction: Workers in open pit iron ore mines are exposed to heat stress which can cause health and safety problems. The purpose of this study was to evaluate heat stress among open-pit mine workers of iron ore based on Wet Bulb Globe Temperature (WBGT) index and also to investigate its relationship with physiological Strain.

Material and Method: This cross-sectional study was conducted on 120 healthy miners, working in an open-pit mine, during summer season, in 2014. Physiological parameters, including core body temperatures and heart rate, were measured according to ISO 9886 standard and physiological strain indices, including Physiological Strain Index (PSI) and Physiological Strain Index based on Heart Rate (PSIHR), were calculated using the equation. Environmental variables as well as physiological parameters were simultaneously measured and recorded during work shift. WBGT index was calculated according to ISO 7243 and using the equation. Statistical analysis was performed using the SPSS software version 22.  

Result: The mean WBGT index was estimated 29.09oC for workers. “Drilling” and “factory and Krasher” units showed the highest and lowest WBGT index values of 31.06oC and 29.05oC, respectively. Workers occupational exposure to heat stress were higher than recommended thresholds based on WBGT index in all work units. A statistically significant correlation was found between WBGT index and physiological strain indices
(P value<0.001). The Pearson’s correlation coefficients were obtained 0.658 and 0.566 respectively, between WBGT index and values of PSI and PSIHR.

Conclusion: WBGT index showed a higher correlation with physiological strain Index; and level of heat stress in all work units of mine was higher than recommended thresholds. Thus, countermeasures should be adopted to control heat stress for the workers in this field.

Introduction: Resilience engineering is a novel approache to risk management and is the inherent ability of a system to adapt their work before, during and after the changes and adverse events in such a way that maintain the system performance under predictable and unpredictable conditions. The aim of this study was to identify indicators of organizational resilience of refineries and ranking them using fuzzy TOPSIS technique.  

Material and Method: A qualitative study was done to identify organizational resilience indicators of refinery complex. The main method of data collection was semi-structured interviews. Indicators were determined using qualitative content analysis and literature review. Weighting and ranking identified indicators was performed using fuzzy TOPSIS technique.   

Result: Eleven indicators were identified as follows: management commitment, performance management system, flow of information/communication, involvement culture, error management culture, education, preparedness, flexibility, innovation culture, change management, and human resource management.

Conclusion: Critical sociotechnical organizations especially refinery complexes in order to improve safety management and resilience situation should focus on effective indicators. Monitoring and improving them will increase safety and the resilience level of organization

Introduction: Kitchen workers are in danger of slip accident because of slippery surfaces created by contaminants like grease, water and food material. The aim of this study was to investigate the prevalence and slip risk assessment in cooking sites of Shiraz.

Material and Method: This cross-sectional study was conducted on 322 cases from commercial kitchens in traditional and fast food restaurants, located in Shiraz, Iran, who was willing to cooperate in the project. (The total number of restaurants was 1303 cases. And simple random sampling method was used). The risk of slips was assessed using Slip Assessment Tool (SAT), developed by Health and Safety Executive (HSE). Prevalence of slip accidents was investigated using a questionnaire among kitchens staffs. Roughness coefficient was measured using Roughness Meter TQC-SP1560. Data analysis was performed using SPSS-22 software.  

Result: The level of slip risk was at moderate level in 47% of studied kitchens and others had low level of slip risk. Slip risk level in kitchens of traditional restaurants was significantly higher than fast foods. The average value of the measured surface roughness was obtained 4191/39 µm. The highest and lowest, respectively 4458/2 and 3977/3 µm were reported. The prevalence of slip accidents was reported to be 50.3%. Most of slip accidents was occurred in the kitchens, and when the floor was wet with water or contaminated with food products.

Conclusion: The results of this study showed that due to differences in the type, method and time of food services and also workload of personnel, slip risk in kitchens of traditional restaurants was higher than fast foods. Approximately, in 50% of studied kitchens, the level of slip risk was assessed as moderate. Some basic interventions in spillage control and cleaning procedures, floor surface characteristics and using slip-resistant shoes are required to reduce the risk of slip in kitchens.

Introduction: Nowadays, demand for protection against radar radiation using electromagnetic shielding is on the rise.  Double-layer or multilayer shielding were devised in order to improve the single layer electromagnetic shielding properties. In this study, we tried to prepare a new double-layers electromagnetic shield and investigate the effect of structural factors such as thickness, similarity in layers and mixing time on the shielding effectiveness for double-layers shields.

Material and Method: This study used the Resin Epoxy EI-403 and Nickel Oxide nanoparticles to prepare single layer shields by casting method (with two different mixing time: 10 and 66 min) in 2, 4 and 6 mm thicknesses and 7 wt% Nickel oxide nanoparticles. Then, in order to prepare double-layers shields, single-layer shields were placed on each other without air space. Scattering parameters were measured by a Vector Network Analyzer (V.N.A) and shielding effectiveness were calculated in X-band radar frequency range.

Result: The highest and the lowest averages of shielding effectiveness in single layer shields were 84.14% and 46.05%, respectively. These values were 66.34% and 41.99 %, in double layers electromagnetic shields. The averages of shielding effectiveness values in the double-layers shields (with 10 min in mixing time) in 6, 8 and 10 mm in thickness were 41.99%, 45.45% and 43.25%, respectively. These values in 66 min in mixing time, increased to 54.30%, 62.07% and 66.34%, respectively.

Conclusion: In this study, the shielding effectiveness in double-layers were less than single layer electromagnetic shields. Although the increase in mixing time improved the shielding effectiveness of both single and double layer shields, it could not increase the shielding effectiveness in double layer shields in comparison with single layer. Also, the increase in mixing time in double-layer shields showed that shielding effectiveness decreased with increasing thickness in these shields. Also, it was seen that using a similar single-layer shield in the structural of a double-layer shield led to an increase in skin depth and multi reflections .It finally reduced the shielding efficiency in double layer. It is suggested that in the future, other studies be conduct to improve the shielding effectiveness in these electromagnetic shields.

Introduction: The responsibility of achieving sustainable development goals in most megacities and subsequently in Tehran megacity are in charge of the municipalities. Since, the goal of municipalities in environmental-friendly activities is to protect the physical and mental health of citizens. Therefore, the sustainability assessment of health performance in municipalities is one of the most significant issues in the field of municipal sustainable development of megacities. The Objective of this study was to develop a tool for assessing the sustainability performance of Tehran municipality in the field of health- related activities and services.

Material and Method: In this research the main sustainability indicators in the field of health performance were extracted and localized by providing an indicator-based tool for Tehran municipality as a case study. To determine the initial set of effective indicators, guidelines and standards related to health sustainability issues were surveyed, and an initial set of indicators were extracted. Afterward, a two-round Delphi method was applied by 12 qualified experts to select the most robust indicators of Health performance and assign the importance of the inclusion for each proposed indicator on a seven-point Likert scale. The mean value set to 70% and the standard deviation less than 1 were considered as the cut value.

Result: The findings resulted in extracting 11 main categories and 28 sustainability indicators of health performance. The set of indicators related to the “green space” and “waste” categories with slight differences gained the first and second position in the health sustainability field respectively, whereas “urban planning”, “active and healthy life” and “health and hygienic services” located in the bottom of the list with the relatively close scores.

Conclusion: The results of this study showed that due to little difference between the score of the main selected categories (less than 1 point difference between the highest and lowest categories) and also due to the fact that the expert panel reached a consensus on the total 11 categories, therefore  in order to achieve municipal sustainable development and improving the health level of citizens in the future, it is essential to have a robust consideration toward applying engineering and management measures against all 11 selected categories.

Introduction: Workers in open pit mines are frequently exposed to extreme heat stress during hot seasons. Several indices including Modified Discomfort Index (MDI) are used to evaluate the heat stress. The aim of this study was to evaluate the MDI and to investigate its relationship with ISO 7243 standard (Wet Bulb Globe Temperature index, WBGT) and physiological parameters of workers in an open pit mine.
 

Material and Method: This cross-sectional study was conducted among 120 healthy male miners in an open pit mine during summer season in 2014. Physiological parameters including body core and skin temperature, heart rate and blood pressure were measured according to ISO 9886 standard. All environmental and physiological parameters were simultaneously measured and recorded during a work shift. The MDI and WBGT indices were calculated using the related formula. Statistical analysis was performed using the SPSS 22 software.  
 

Result: According to the criteria of MDI, about 29 percent of workers had the average level, 68 percent of workers experienced the intense level and 2.5 percent suffered from the extreme level of exposure to the heat stress. No case of light level exposure to heat stress was obtained among workers. A significant correlation was found between MDI and ISO standard index (WBGT). Statistically significant correlation were also found between MDI and physiological parameters (P<0.001); in which the highest correlation coefficient was found for the heart rate variable (r=0.589).
 

Conclusion: Based on MDI, a high percentage of open pit mine workers were at risk of heat stress hazards. MDI had a moderate correlation with physiological parameters of the workers and showed a remarkable correlation with the WBGT.

Introduction: Risk assessment is a main tool in safety management process as it can help managers to choose corrective actions by providing appropriate information. The purpose of this paper was to select the optimal corrective actions among the proposed ones by the experts based on mathematical modeling, taking into account the standards and also the limitations including the cost.

Material and Method: In this paper, a model was presented to find the optimal corrective actions regarding the organization goals (maximum in risk reduction value) and the limitations such as cost and level of acceptable risk. Due to extensive number of solutions, Genetic Algorithm (GA) is used for solving the problem.

Result: To show the capability of this method in an industrial environment, a power generation industry with 40 hazards was considered as the case study. Then, the risk of hazards was estimated and corrective actions were determined for each of them. Using the proposed model, corrective actions were selected optimally, with the least possible cost; all risks were reduced below the level of organizational acceptable risk.

Conclusion: It was shown that the optimal corrective actions using mathematical modeling are selected with high precision in acceptable time. This method is suggested as an alternative for conventional qualitative methods based on expert’s opinions.