Showing 20 results for Ahmadi
Akram Tabrizi, Farideh Golbabaei, Hamid Shirkhanloo, Mostafa Jafarizaveh, Kamal Azam, Rasoul Yarahmadi,
Volume 6, Issue 2 (6-2016)
Abstract
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.
Monireh Khadem, Farnoush Faridbod, Parviz Norouzi, Abbas Foroushani Rahimi Foroushani, Mohammad Reza Ganjali, Seyed Jamaleddin Shahtaheri, Rasoul Yarahmadi,
Volume 7, Issue 1 (4-2017)
Abstract
Diazinon is commonly used for pest control in the agricultural fields because of its relatively low cost and high efficiency. Due to the increasing application of pesticides, reliable and accurate analytical methods are necessary for their monitoring. This work was aimed to design the high selective electrochemical sensor for determining of diazinon in biological and environmental samples. The composition of sensor was modified with multi-walls carbon nanotubes and a molecularly imprinted polymer (MIP). A diazinon MIP was synthesized and applied in the carbon paste electrode (CP). The prepared sensor was used to determine the concentration of analyte. Parameters affecting the sensor response, such as sample pH, electrolyte concentration and its pH, and the instrumental parameters of square wave voltammetry, were optimized in different levels to select the optimum conditions for analysis of diazinon. The MIP-CP electrode showed very high specificity for determining the analyte. The obtained linear range was 1×10-6 to 5×10-10 mol L-1. The detection limit was 2.7×10-10 molL-1. This sensor was successfully used to determine the diazinon in environmental and biological real samples without special sample pretreatment before analysis.
Bahram Harati, Seyed Jamaleddin Shahtaheri, Ali Karimi, Kamal Azam, Alireza Ahmadi, Maryam Afzali Rad, Ali Harati,
Volume 7, Issue 2 (6-2017)
Abstract
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.
Rasoul Yarahmadi, Zabiolah Damiri, Javad Sharifi,
Volume 7, Issue 2 (6-2017)
Abstract
Introduction: Nowadays, many modern industries require an environment with no contamination by particles and bacteria. An enclosed clean room environment is a place where parameters such as airborne particles, temperature, humidity, air pressure and air flow pattern is controlled. The aim of this study was to evaluate functional parameters of a clean room in a selected pharmaceutical industry.
Material and Method: This study was an experimental study conducted in 2015 in a pharmaceutical industry. The air flow rate and flow rate with airflow capture hood was used and multi sensor devices for measuring temperature, humidity and pressure of multi-sensor device. HEPA filter leakage test and counting concentration of particles in the cleanroom was done according to the ISO 14644 – 3(2005) standards using aerosol photometer and aerosol generator. In this study, 6 clean room relating to the 3 cleanliness classes B, C and D (in accordance with standard EU GMP) were evaluated. Meanwhile, both the 2 and 3-dimensional flow model using Computational Fluid Dynamics Software was simulated in this study.
Result: Measuring the parameters flow rate and air velocity, temperature (average temperature 20 ° C), relative humidity (below 50%), pressure (pressure less than 15 psi) for every three classes of cleanliness are all acceptable and less than the proposed standard. Furthermore, the results of modelling showed that the pattern of air flow in the room is correct paths in circulation. In the case of leakage test filters, the filter 29 filters tested 5 was leaking and ultimately determine the HEPA filters remove particles that average efficiency is 99.99%.
Conclusion: This study showed that the high volume and good quality of air entering the clean room affect the optimal efficiency and air flow rate, pressure drop and air penetration of the HEPA filters Also, the results of study show that the concentration of airborne particles in clean room is depend on the air flow rate and speed and adopting a good air flow pattern will affect the particle concentration.
Peyman Yari, Rasoul Yarahmadi, Yahya Khosravi, Masoud Salehi, Hamid Kariznovi,
Volume 7, Issue 3 (9-2017)
Abstract
Introduction: Correspondence analysis method and preparation of accidents and occupational hazards pattern is able to predict and anticipate accidents and is automatically prioritize the risks and injuries. The aim of this study was to present accidents and occupational hazards pattern based on risk-injury groups, which use it to manage of occupational accidents.
Material and Method: The report of occupational accidents, registered in the social security organization was collected in a period of ten years from 2005 to 2015 (222,300 accidents). Types of risk and injuries to any of the accidents specified based on International Labor Organization criteria and risk of injury were classified in a matrix (18 × 18). Risk-injury groups were separately identified using correspondence analysis and collapse process, as patterns of accidents and occupational hazards. In the mentioned patterns, the relationship between risks and damage can be identified, as it facilitates decision-making in risk assessment in companies covered by the social security organization.
Result: According to the findings, three groups of occupational accidents were obtained and variables of these three groups extracted from the obtained patterns. The first group included six risks and seven injuries that the risks variables were: contact with hot materials, accidents caused by caustic and corrosive substances, contact with chemicals, accidents caused by toxic substances, contact with electrical equipment, explosion and fire, and injuries were: burns, other injuries, multiple injuries, gas poisoning, suffocation, poisoning, environmental hazards. The second group included seven risks and six injuries that the risks variables were: accidents caused by displacement, projections of fragments or particles, accidents caused by machine tools, slipping, falling people, falling objects, other accidents and injuries were: twists and sprains, dipping the objects in the body, objects in the eyes, cuts and amputations, superficial wounds, deep wounds. Finally, the third group included five risks and five injuries that risks variables were: Falling under the rubble, accident with vehicle, accidents caused by displacement, colliding of persons against objects, projections of fragments or particles, accidents caused by manual tools, trapped between objects, accidents caused by machine tools and injuries were: fractures, dislocation, back pain, hitting, contusions and crushing. It should be noted that the study of these patterns can be used to identify and prioritize of occupational accidents.
Conclusion: The proposed groups make new opportunities for development of the applications to analyze, interpret and automate management of occupational accidents in order to minimize uncertainty and increase its objectivity. Its advantage over other similar analyses can be considering both the risks and injury and to obtain groups of two variables. Due to the frequency and distribution of mass of risk and injury variables in the groups, the risk and injury variables of group 3 are the most important, and the risk and injury variables of group 2 are less important and the risk and injury variables of group 1 have the least importance.
Taleb Askaripoor, Gholam Abbas Shirali, Rasool Yarahmadi, Elahe Kazemi,
Volume 8, Issue 1 (4-2018)
Abstract
Introduction: Extensive human and economic losses due to the fire accidents shows the necessity of scientifically dealing with major industrial fires, , investing in the development of fire protection technologies and determination of the most effective techniques to limit damages. This study is conducted to evaluate the effect of active and passive protection methods on reducing the level of fire risk, in the control room of a thermal power plant.
Material and Method: In the first phase of this study, fire risk level for buildings, goods, occupants and activities was calculated using Fire Risk Assessment Method for Engineering. In the second phase, from 36 sub-factors affecting risk level, three sub-factors of passive protection measures and two sub-factors of active protection measures were analyzed and modified, in reducing the fire risk level of occupants.
Result: The results of the present study showed that occupants’ fire risk level (20.64) is above the acceptable level. Correction of three sub-factors, including constant fire load, floor number, and changing the dimensions and area of the control room up to 40% and installing an automatic fire extinguishing system and training the occupants to use fire extinguishing equipment and emergency evacuation up to 33%, is effective in reducing the fire risk level.
Conclusion: Passive and active protection methods, despite their impacts on reducing the level of risk, cannot provide an acceptable level of fire safety independently. Therefore, combined use of these methods is essential to protect buildings and people, and prevent any interruption in the system’s activities.
Masoumeh Lotfi, Mohammad Reza Monazzam Esmaielpour, Nabeioallah Mansouri, Saeid Ahmadi,
Volume 8, Issue 2 (6-2018)
Abstract
Introduction: Using diesel generators is necessary for activities like welding in construction sites and it is often accompanied with noise pollution. The aim of this study was to evaluate noise pollution induced by diesel generators in construction activities in one of the districts of Tehran city.
Material and Method: In this descriptive study, 14 construction sites were selected for the evaluation of noise pollution in Tehran, district 4. Background and diesel generators sound pressure level were measured in accordance with BS 5228(2015) and noise guidance in the area around the construction sites. Diesel generators sound pressure level at 4 points and also the audio frequency analysis, one meter away from the device was measured at a random locations around it. TES-1358, Type 2(Taiwan) sound level meter was used to measure sound pressure level and calibration was performed before and after noise measurement. The validated Noise annoyance questionnaire adopted from ISO15666 standard, completed by the residents. T test, correlation and analysis of variance was performed to analyze data using SPSS software ver. 22.
Result: The mean equivalent sound level of diesel generators background noise were respectively 76 ± 4.05 dB(A) and 46.2 ± 1.09 dB(A) around the construction sites. Diesel generators noise around the construction sites was higher than the noise limit (background noise plus 5 dB)(P Value <0.05). The highest (95.3 ± 0.33 dBA) and lowest (90.9 ± 0.63 dBA) average sound pressure level was related to Benz355 and Perkins generators. One-way ANOVA statistical analysis showed significant differences in the average sound pressure level of various diesel generators between the devices (P Value <0.05). The mean sound pressure level among 190 sound monitoring stations in the interior parts of the construction sites were about 81.11 ± 4.6 dB(A). The experienced noise annoyance was evaluated higher than the average by 73.4 percent of residents. Residents’ noise annoyance and noise level around construction sites were significant using Pearson correlation (R=0.486, P value <0.05). Dominant noise frequency and associated sound pressure level of diesel generators were measured 63 Hz and 84.4 dBA, respectively.
Conclusion: Diesel generators noise in the area around the construction sites was higher than the environmental noise limit and it was accompanied with abundant noise annoyance for residents around these construction sites. Therefore, due to the lack of environmental rules related to construction industry noise pollution in Iran, assessment and approving of such rules is essential to reduce noise annoyance in urban areas.
Behzad Fouladi Dehghi, Seyed Moslem Abedini, Sanaz Karimpour, Kambiz Ahmadi Angali,
Volume 9, Issue 3 (9-2019)
Abstract
Introduction: Determining the VO2 max of individuals is of great importance. The VO2 max refers to the maximum oxygen that can be consumed in the body in one minute and depends on factors such as physical conditions, environmental parameters, and physiological characteristics of the individual.. Noise and heat are among the factors influencing VO2 max (also called maximal oxygen uptake or maximal aerobic capacity), which affects the performance of respiratory system, via different ways. Therefore, the purpose of this study was to investigate the simultaneous effect of noise and heat on VO2 max in Ahvaz university of medical sciences’ students
Material and Methods: The present study was conducted on 50 volunteer students from the Ahvaz Jundishapur University of Medical Sciences, Iran. The VO2 max index was measured using the ergometer bicycle test and the Astrand protocol in nine modes of exposure to heat (21, 38 and 48°C), WBGT (18.34, 32.46 and 41.25°C) and noise (75, 85 and 95 dB (A)). In order to carry out the test according to the Astrand protocol, the person pedaled on the bike for six minutes at a constant load and a speed of 50 rpm to increase the heart rate to more than 120 beats per minute. The heart rate was monitored while working with the ergometer bike using a Polar branded sensor mounted below the individual chest. SPSS vol.22 software, Friedman test and paired t-test were used to analyze the data.
Results: The mean VO2 max in the second test condition (heat:21°C , WBGT : 18.34°C ,noise:85 dB) and the third test condition (heat:21°C ,WBGT : 18.34°C ,noise:95 dB) were not significantly different from the first (normal) mode, but the VO2 max value significantly decreased (P<0.001) from the third mode to higher levels with increasing the levels of heat and noise.
Conclusion: Since one of the objectives of ergonomics is to create an environment in consistent with human capacities, it is essential to have knowledge of VO2 max. Regarding the effect of heat and noise on VO2 max of individuals and also the direct relationship between VO2 max and PWC) Physical Work Capacity (, in order to protect the health of individuals and increase their productivity, it is necessary to carry out control measures in warm and noisy environments.
Reza Yeganeh, Rasoul Yarahmadi, Zabiholah Damiri,
Volume 10, Issue 3 (8-2020)
Abstract
Introduction: Occupational health is one of the important issues that can affect productivity and economic development of an organization. This study aimed to determine the effect of didactic interventional Ergonomic-Safety program on workers’ productivity of an assembling industry.
Methods and Materials: This interventional study was conducted on 54 workers of assembling part of an electronic industry. Firstly, QEC method was used for Ergonomic assessment of work place and Hersey-Goldsmith questionnaire was applied for assessment of productivity. Then a comprehensive program was provided using findings of first stage assessment and identifying of existing failures. Second assessment of Ergonomic condition and productivity was done again by using QEC method and Hersey-Goldsmith questionnaire within three month of interventions. Data was analyzed by using of R software.
Results: Mean total productivity score and mean whole body score of QEC were 75.24 and 99.40 in before intervention phase respectively. In after intervention phase, Mean total productivity score and mean whole body score of QEC were 80.16 and 97.92 respectively. Data analysis by paired-samples t-test shows that difference of productivity score in before and after intervention phase was significant (P-value˂0.05). But difference of whole body score of QEC score in before and after intervention phase was not significant (P-value>0.05).
Conclusion: Accomplishment of Ergonomic-Safety intervention had a positive effect on productivity score whereas had not significant effect on general condition of body limbs.
Mohsen Sadeghi Yarandi, Farideh Golbabaei, Ali Karimi, Ali Asghar Sajedian, Vahid Ahmadi,
Volume 10, Issue 3 (8-2020)
Abstract
Introduction: 1,3-Butadiene is a carcinogenic compound that can be emitted to the atmosphere from several sources like petrochemical industry. One way to determine the level of carcinogenic and health effects of respiratory exposure to pollutants in the workplace is to use risk assessment methods. The aim of this study was to comparative assessment of carcinogenic risk of respiratory exposure to 1,3-Butadiene in a petrochemical industry by the US Environmental Protection Agency and Singapore Health Department methods.
Material and method: This cross-sectional study was carried out in 2018 in a petrochemical industry that producing copolymer ABS (acrylonitrile, butadiene, styrene) in Iran. Occupational exposure to 1,3-Butadiene was measured according to the NIOSH 1024 method. Cancer risk assessment was done according to the United States Environmental Protection Agency (USEPA) and Singapore semi-quantitative methods.
Results: The average occupational exposure to 1,3-Butadiene during work shift among all participants was 560.82 ± 811.36 µg.m-3 (0.253 ± 0.367 ppm) and in all cases was below the occupational exposure limit. The average lifetime cancer risk in USEPA method in the present study was 2.71 × 10-3, Also in this method 82.2% of all exposed workers were in the definite carcinogenic risk level and 17.8% were in the probable carcinogenic risk level. The results of the Singapore health department method showed that 91.2% of all subjects were in the probable carcinogenic risk level and 8.8% were in the definite risk level.
Conclusion: The findings of the present study showed that the results of the Singapore semi quantitative risk assessment method are not in good agreement with the results of the quantitative risk assessment method proposed by the US Environmental Protection Agency. Therefore, given the high accuracy and thoroughness of the US Environmental Protection Agency's risk assessment methodology as a worldwide reference method for assessing the carcinogenic and health risk of exposure to chemicals, it is recommended to use this method instead of the Singapore method in future studies.
Vahid Ahmadi Moshiran, Ali Karimi, Farideh Golbabaei, Mohsen Sadeghi Yarandi, Ali Asghar Sajediyan, Aysa Ghasemi Koozekonan,
Volume 10, Issue 4 (11-2020)
Abstract
Introduction: Styrene (C₆H₅CH=CH₂) is known as one of the volatile organic substances produced or used in petrochemical industries. Exposure to this chemical compound can thus lead to respiratory diseases. Therefore, this study aimed to evaluate occupational exposure to styrene vapor and to determine the risks of its health consequences in petrochemical industry workers through a quantitative method.
Material and Methods: In this descriptive cross-sectional study, a total number of 150 samples from 50 employees were studied using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. The samples were then analyzed by the Varian CP-3800 chromatograph. Upon determining exposure to styrene vapor, the risk assessment of the health consequences of styrene in the workers in the given industry was evaluated via the relationships established by the United States Environmental Protection Agency (US/EPA).
Results: According to the results, the polybutadiene latex unit (PBL) was observed with the highest average exposure (0.44 mg.(kg-day)-1). Therefore, the top predictors of carcinogenic and non-carcinogenic risks were valued 0.44 and 0.71, respectively, for the PBL unit. Given the lowest average exposure (0.0012 mg.(kg-day)-1) in the drying unit, the prediction revealed the most moderate carcinogenic (0.1 ×10-5) and non-carcinogenic risks (2×10-3) for the same employees.
Conclusion: Overall, the health risk was higher than the permissible limit in the petrochemical industry studied, especially in the PBL unit. Therefore, it is recommended to make use of artificial ventilation, notably the local type, in addition to the natural ones.
Mehran Pourhossein, Reza Pourbabaki, Elahe Roudi, Vahid Ahmadi Moshiran, Homa Maleck Khani, Samane Khodaverdloo,
Volume 10, Issue 4 (11-2020)
Abstract
Introduction: Errors are a byproduct of human information processing or cognitive functioning. Although everyone is disposed to an error while performing various activities, individual differences in cognitive abilities can lead to various types and rates of errors committed in similar situations. Human errors are one of the most important challenges in work environments, including health care systems, wherein such errors are abundantly occurring. Errors in the delivery of correct medications due to the resemblance in appearance and name are thus one of the cognitive errors that come about in health care systems. The main purpose of this systematic review was to evaluate evidence and approaches recently practiced to reduce medication errors caused by the use of look-alike-sound-alike (LASA) medications.
Material and Methods: The study was conducted on August 30, 2018, through searches in the databases of PubMed and Embase, all available years, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) instructions. The searches were done in the titles or abstracts of the articles using the intended terms and the Medical Subject Headings (MeSH) index in combination. These studies were selected based on the inclusion and exclusion criteria and then categorized based on the type of interventions and outputs. Finally, the data were analyzed descriptively.
Results: The research designs and methods varied widely among the studies. There were also discrepancies in the number of participants, number of tests, type of medications, and test conditions. The approaches examined in these studies were tall-man lettering, color-coding, label background variations, and use of signs and symbols. Accordingly, 11 studies had utilized tall-man lettering and the most important reported in all articles were “error rate” and “response times”. As well, a wide range of medication names had been tested. It should be noted that medication
Conclusion: errors have different dimensions, but the errors caused by the look-alike-sound-alike (LASA) medications and the effect of tall-man lettering of medication name were only investigated in the present study. Laboratory studies in this respect have shown that tall-man lettering contributes to mitigating the rate of errors, which might be due to the better legibility of labels, but evaluations in real work environments are needed to reinforce this conclusion. There is also insufficient evidence to support color-coding, as well as several other approaches such as use of signs and symbols. Because of the novelty of the studies in this field, no uniform mechanism has been so far introduced.
Sepideh Keyvani, Mohammadreza Monazzam Esmaielpour, Fatemeh Fasih-Ramandi, Akbar Ahmadi Asour, Malihe Kolahdouzi, Zahra Hashemi,
Volume 11, Issue 3 (9-2021)
Abstract
Introduction: The acoustic performance of natural fiber adsorbents has been investigated in numerous studies. A part of these materials show a poor adsorption within the frequency range of less than 1000 Hz. In the present study, attempts were made to investigate the effect of layout sequence of double-layered composites consisting of natural and synthetic fibers on improving the acoustic adsorption coefficient of natural fiber in the low-frequency range (63 to 1000 Hz) using the numerical finite element method.
Material and Methods: In this study, the finite element method and the Johnson-Champoux-Allard model in COMSOL software version 5.3a were used to investigate the acoustic performance of the double-layered composites consisting of natural and synthetic adsorbents. The acoustic absorbers under study included date palm fiber, polyurethane foam and cellular rubber. Each double-layered composite included a date palm fiber with 10mm in thickness and a synthetic adsorbent (polyurethane foam or cellular rubber) with 10mm in thickness. In sum, four double-layered composite structures with different layouts of adsorbents in each structure were studied.
Results: The location of natural fiber can play a critical role in the acoustic performance of the double-layered composite structures such that comparing the studied double-layered composites revealed that when the natural fiber was the first layer exposed to the normal sound in the double-layered composites with 20mm in thickness, the trend of acoustic performance was approximately the same as the single-layered composite of natural fiber with 20mm in thickness; but in the composite structures, when the synthetic adsorbent was the first layer exposed to the sound, the trend of acoustic absorption was improved.
Conclusion: On the basis of the results, the double-layered composite structure with a higher-density and lower-porosity upper layer showed a better acoustic absorption trend than the single-layered composite including the natural adsorbent.
Aysa Ghasemi Koozekonan, Vahid Ahmadi Moshiran, Mohsen Sadeghi Yarandi, Hamedeh Golmohammapour, Babak Sarbaz, Seyed Abolfazl Zakerian,
Volume 11, Issue 3 (9-2021)
Abstract
Introduction: One of the most important factors affecting quality of work-life (QWL) is the workload in the form of mental and physical. The increased workload may reduce the level of performance of workers. Therefore, the present study aimed to evaluate the relation of the mental and physicalworkload with the QWLof workers in the foundry industry.
Material and Methods: This cross-sectional study was conducted on 218 male workers in a foundry industry and the work units with high work stress were selected. The NASA-TLX, physical load and the Walton questionnaires were used to collect and evaluate the workload and the QWL.The SPSS software was used for data analysis.
Results: It was clarified that there was a significant inverse relationship between QWL with physical load (P = 0.001) and mental workload (P = 0.01). The comparison of mean QWL between different groups of demographic variables showed that the only significant relationship was between different age groups and QWL (P = 0.003). Finally, it was found that the variables of physical load, mental workload and age had a significant simultaneous effect on the mean score of QWL (P<0.05).
Conclusion: The findings showed that there was a significant relationship between QWL and mental and physical workloads.
Masoud Feyzi, Ali Jafari, Hojat Ahmadi,
Volume 12, Issue 2 (6-2022)
Abstract
Introduction: Due to the non-developed mechanization situation, chainsaw is a widely used tool in Iranian forests. This tool can trigger unwelcome disorders (e.g., white finger syndrome) due to the transmitted vibrations from its handle to the body members. Characterizing these vibrations can result in minimizing the intensity of these disorders. This study aims to investigate the effect of different hardwood species (Beech, Hornbeam, and Alder) on the vibrations transmitted to the wrist and arm.
Material and Methods: Experiments are conducted during four operations including Beech-, Hornbeam-, and Alder-cross-cutting and without cutting as the control sample. Vibration accelerations in three directions of a local Cartesian coordinate system are measured at three points including chainsaw handle, operator's arm and wrist. Using the time and frequency spectra of vibration accelerations, root mean square (RMS), total vibration acceleration, total vibration transmissibility, and frequency-weighted vibration acceleration are calculated based on ISO 5349 (2001) and ISO 10819 (2013) standards. The calculated parameters were statistically analyzed in SAS.
Results: The results showed that variations in wood species could significantly affect the RMS at all three points. The RMS magnitude decreases from handle towards the arm. Interestingly, a significant variation in vibration transmissibility is observed in different frequencies. This study confirms that body organs can damp the high-frequency vibrations better than the low frequency ones.
Conclusion: Although the RMS for cutting operations is less than the control sample, frequency-weighted vibration acceleration and consequently the risk of white finger syndrome is higher in cutting regimes. Furthermore, some vibration accelerations (below 40 Hz for wrist and below 25 Hz for arm) are amplified during transmission despite significant damping in total vibrations.
Akbar Ahmadi Asour, Mohammadreza Monazzam, Ebrahim Taban, Zahra Hashemi, Somayeh Amininasab,
Volume 13, Issue 3 (9-2023)
Abstract
Introduction: The aim of this study was to investigate the effect of particle size (mesh) on the sound absorption coefficient of the absorbers made from Arundo Donax reed and to determine the optimal mesh for sound absorption.
Material and Methods: After crushing the reed stems in 10, 30, 20, 16, and 40 mesh sizes, they were washed with 5% NaOH. To make the samples 3 and 10 cm in diameter, 10% PVA was used as a binder, and the impedance of the two-channel tube was used according to ISO 10534-2 standard to determine the absorption coefficient. 22 samples of meshes 16 and 20 were made to achieve the optimal mesh based on the optimized RSM method, and the SAA index was used to compare the samples and determine the optimal mesh.
Results: The highest absorption peak was related to meshes 16 and 20 at the frequency of 2500 Hz, which is 0.94 and 0.98 ,respectively. The effect of increasing the thickness and density on the absorption coefficient is evident. The results have shown the effect of increasing the thickness and density on the absorption coefficient in mesh 20 in such a way that by increasing the density from 150 to 250 and the thickness from 10 to 30 mm, the absorption coefficient has increased from 35 to 63.5%. The optimal sample was mesh 20 with a thickness of 30 and a density of 250 kg/m3, which had the highest average absorption (SAA=0.57). The greater distance between the real and imaginary parts of the impedance shows the reactivity of the sample. In mesh 16 this distance is greater, as a result, mesh 16 has more reactivity and correspondingly less absorption.
Conclusion: The role of particle mesh as one of the important and influencing parameters on absorption coefficient has been investigated in this study.
Pourya Ahmadi Jalaldehi, Jila Yavarian, Farideh Golbabaei, Saba Kalantary, Abbas Rahimi Foroushani, Hossein Abbaslou,
Volume 13, Issue 4 (12-2023)
Abstract
Introduction: The COVID-19 pandemic has been a significant global health challenge. Primary care services, such as screening health centers, were crucial in identifying infected individuals. However, these centers were often crowded and posed a high risk to staff and non-COVID-19 patients. This study aims to assess the risk of airborne transmission of SARS-CoV-2 in such settings through simulation.
Material and Methods: In this study, waiting and sampling rooms of a COVID-19 healthcare center were simulated using different scenarios. Then, the Quanta emission rate was estimated using the viral load in the sputum of infected individuals. Finally, the airborne transmission risk of SARS-CoV-2 was determined using the Wells-Riley method for scenarios of wearing and without masks.
Results: The study showed that the Quanta emission rate in an unmodulated speaking activity was higher than other expiratory activities in both units (p <0.001). Also, the total amount of Quanta was slightly higher in the sampling room than in the waiting room, which was not statistically significant. On the other hand, the calculation of transmission risk showed that the probability of airborne virus transmission in the sampling room was higher (about 2 to 8%). In addition, wearing masks reduced the possibility of airborne transmission of the virus significantly (77 to 81%).
Conclusion: This study shows that the level of risk in the sampling and waiting rooms is moderate. Masks also significantly reduce the possibility of airborne transmission of SARS-CoV-2. Taking appropriate health and safety measures such as avoiding crowds, wearing masks, whispering, and monitoring social distancing can reduce the plausibility of airborne transmission of the SARS-CoV-2 virus.
Gholamreza Moradi, Sana Mohammadi, Abdolrasoul Safaiyan, Saeid Ahmadi, Mehrnia Lak,
Volume 14, Issue 1 (3-2024)
Abstract
Introduction: Disturbing noise can cause physical and mental illnesses among workers; for this reason, it is necessary to restrain it, especially in workplaces. Using sound-absorbing materials with suitable acoustic properties has been a growing trend in mitigating noise. This study aimed to improve the acoustic properties of polyurethane foam (PUF) as a sound absorber.
Material and Methods: In the present study, PUF was synthesized with different percentages of clay nanoparticles (0 -1.2 wt.%), and then the Sound Absorption Coefficient (SAC) of the synthesized PUF was measured by the acoustic impedance tube in the frequency range of 63 to 6400 Hz according to the ISIRI 9803 standard without an air gap behind the sample. The morphology of the foam was also investigated by Scanning Electron Microscope (SEM).
Results: The results showed that the addition of clay nanoparticles to PUF improved the sound absorption behavior of the samples, and the best sound absorption behavior was for PUF with 1.2% weight of nanoparticles at low frequencies (500-2600 Hz). This increase in the absorption coefficient can be due to the increase in the number and smaller size of the pores with the increase in the amount of nanoparticles in PUF.
Conclusion: This study illustrates that the incorporation of clay nanoparticles into PUF at varying percentages results in an enhanced absorption coefficient. The presence of clay nanoparticles leads to a reduction in cell size and an increase in the number of pores, consequently enhancing surface friction. The absorption coefficient was observed to increase with the growing concentration of clay nanoparticles in PUF.
Mahdi Mohammadiyan, Omran Ahmadi, Mehdi Yaseri, Ali Karimi,
Volume 14, Issue 2 (6-2024)
Abstract
Mahdi Mohammadiyan, Nafiseh Nasirzadeh, Akbar Ahmadi Asour, Sepideh Keyvani, Fatemeh Fasih-Ramandi, Farideh Golbabaei,
Volume 14, Issue 2 (6-2024)
Abstract
Introduction: In recent years, exposure to nanomaterials has been known as a challenge among occupational health experts. In this line, personal protective equipment has been considered as a solution to reduce the worker’s exposure. Since respiratory and skin tracts represent the most common workplace exposure routes, knowledge of the efficiency of respiratory and skin protection equipment is particularly important. So, the aim of this study is the assessment of the efficiency of respiratory and skin protection equipment toward controlling nanoparticles in the workplace with a scoping review approach.
Material and Methods: This study was conducted in 2022 with a scoping review approach. Arksey and O’Malley’s five-step framework was chosen as the research method. The search strategy was followed in the databases necessary to access the research data, including PubMed, Google Scholar, Science Direct, Web of Science, and Scopus. Also, EndNote X9® and Microsoft Excel software were used to collect and analyze studies, respectively.
Results: In the first step, 1014 articles were identified. Finally, 38 articles were included in the study to examine quantitative and qualitative information about the efficiency of respiratory and skin protective equipment. Twenty-five articles were related to breathing masks, and six studies were about protective gloves, and seven other articles were devoted to protective clothing. According to the studies of breathing masks, the mean total penetration of nanoparticles was estimated at 2.27%. Also, based on the studies of protective clothing, the maximum penetration of nanoparticles was 30nm for protective clothing made of polypropylene and polyethylene with different layers.
Conclusion: Although the efficiency of existing personal protective equipment showed a good result for controlling nanoparticles, the size of nanoparticles is one of the essential parameters in determining the efficiency of the equipment, which should be considered the workplaces. So, it is recommended that more studies be considered to improve their efficiency, and standard tests should be developed to evaluate them.
