Journal of Health and Safety at Work

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Introduction: Previous studies have been conducted on the effects of exposure of industrial workers to high levels of noise and their association with mental health or exposure of people to harmful levels of environmental noise. In this study, we investigated the association between moderate noise levels and the symptoms of depression, anxiety, and stress in non-industrial workers.
Material and Methods: This study is a Cross-Sectional study that was conducted using the enrollment phase data of the Tehran University of Medical Sciences Cohort (TEC) study. The study population consisted of 3899 workers of Tehran University of Medical Sciences who were employed in seven occupational groups of the university, Office Workers, Healthcare workers, technical personnel, services workers, security guards, and radiology-radiation units. Exposure to moderate noise level was examined using the Leq10min index, and the Depression Anxiety Stress Scales were examined on the mentioned population by DASS-42 questionnaires.
Results: The results showed that the prevalence of severe to very severe symptoms of depression, anxiety and stress were 8.2, 7.9, and 11% respectively. Also, it was observed that 14.5% of the participants of the study were exposed to noises of more than 70 dB(A). Furthermore, the results indicated that the highest average noise was equal to 71.3 dB(A) for the technical staff group, and the lowest value with an average of 59.1 dB(A) was recorded for the office workers group. The symptoms of severe to very severe depression was associated with exposure to noises above 70 dB(A) (OR:5.22) anxiety (OR:1.16), stress (OR:1.17) and socioeconomic status (OR:1.84). The severe to very severe anxiety was associated with stress (OR: 1.25). On the other hand, the symptoms of severe to very severe stress was associated with variables of age (OR:0.99), gender (OR:0.46), socioeconomic status (OR:1.52), having job management position (OR:0.81) and having healthcare working job (OR:0.65).
Conclusion: Regarding the obtained results of the present study, it was concluded that exposure to moderate noise levels had positive and significant association with depression in non-industrial workers. In non-industrial work environments, exposure to moderate noise levels is and can be independently associated with depression.

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Introduction: One of the most important complications of exposure to noises is changes in the gene expression patterns. Irreversible damage to the inner ear, such as noise-induced hearing loss (NIHL), is caused by tissue damage and changes in the gene expressions in the auditory system. Changes in the GJB2 gene expression pattern lead to autosomal deafness at different loci. The present study aims to evaluate the GJB2 gene expression in cochlear tissue exposed to white noise.
Material and Methods: In this study, ten male Westar rats were divided into two experimental (W1, W2) groups of six rats and a control (normal) group of four rats. Two experimental groups were exposed to constant white noise in the frequency range of 100-20000 Hz and the sound pressure level of 118-120 dB. In order to study the histology and gene expression, after a cochlea biopsy, the histological tests, RNA extraction, cDNA synthesis, and qRT-PCR analysis were performed.
Results: The results showed that the transcript level of GJB2 was significantly decreased in both experimental groups W1 and W2 by 0.02 and 0.12-fold, respectively (p <0.05). Also, the results of the histological study showed that cochlear tissue was more seriously damaged in the W1 group than W2.
Conclusion: It can be concluded that a significant reduction in the GJB2 gene expression and irrevocable damage to auditory nerve ganglion and Reissner membrane (vestibular membrane) caused changes in the gene expression patterns in cochlear tissue and developed the risk of non-syndromic sensorineural hearing.

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Introduction: The noise could affect some aspects of human health, including the cognitive performance. In addition to sound pressure level and exposure time, the psychoacoustic features of noise may cause destructive effects on humans. A few recent studies have been conducted on effect of sound quality on cognitive performance. This study aims to find the noise loudness and sharpness levels as the most destructive effects on human cognitive performance.
Material and Methods: This was a cross-sectional study on 10 male students of Tehran University of Medical Sciences. The Noises were generated in two channels that the left channel produced the pink noise as a background noise. The pink noise loudness and sharpness were 19.7 sone and 2.49 acum, respectively. The right channel generated noises with different loudness and sharpness levels the noise loudness ranged from 8.87 to 67.9 sone and the noise sharpness ranged from 1.07 to 6.4 acum. Finally, ten noises with different loudness and sharpness were applied. The students were exposed to ten different types of noise and a silent condition. The Mathematical Problem Solving Task (MPST) test was performed to assess cognitive performance. The reaction time and the accuracy rate were measured after 5 minutes of noise exposure. Data were analyzed by SPSS (ver. 22). P< 0.05 was considered as significant level.
Results: The mean reaction time and the mean accuracy rate increased with the sharpness level.  However, alteration in the loudness and sharpness levels had no significant effect on the speed and accuracy of students. Performance speed increased in noise 3 with the highest loudness (L=67.9, SH=1.07) in comparison with the silent condition (p-value=0.05). The mean accuracy rate in exposure to the noise 9 reduced in comparison with silence (p-value=0.04)
Conclusion: Different levels of psychoacoustic features had no significant effect on the cognitive performance parameters. Although, the accuracy rate and the reaction time decreased in noises 9, the sharpest noise, and 3, the loudest noise, in comparison to the silence, respectively.

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Introduction: Nosocomial infection (NI) is an infection occurring in a patient after 48 hours of hospitalization or up to 72 hours after discharge from the hospital, which was not present or incubating at the time of admission.  Hospital accreditation standards have a significant impact on the prevention and control of NI. Nevertheless, Iran’s hospital accreditation standards face challenges. The aim of this study was to compare the accreditation standards of NI prevention and control in Iran and leading countries.
Material and Methods: This research was conducted using the comparative review method in 2020. Hospital infection prevention and control (IPC) standards of Iran Hospital Accreditation Program was compared with those of international accreditation programs in the United States, Canada and Australia. Thematic analysis method was used to analyze the qualitative data.
Results: Iran and the United States had the highest share of nosocomial IPC standards. The Iranian Hospital IPC standards approximately comply with 62.1%, 46.6% and 49.9% of Hospital IPC standards of the United States, Canada and Australia, respectively. A hospital infection management system including constructs of NI leadership and management, NI planning, NI education, employee management, patient management, resource management, process management and outcomes is necessary for IPC. Iran Hospital Accreditation Program places great emphasis on process and resource management and less importance to leadership and management, planning, employee management, patient management and outcomes.
Conclusion: The Iranian Hospital Accreditation Program is progressing. However, its IPC standards need to be reviewed and updated. Using a systems approach including structures, processes and results in the development of hospital accreditation standards, leads to the optimal use of hospital resources and achieving better results.

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Introduction: Over recent years, various programs have been conducted to reduce noise, indicating the increasing concerns of society over noise pollution. This study has been performed to enhance the performance of parallel barriers on two sides of a highway considering the surrounding buildings.
Material and Methods: The 2D boundary element simulation method was employed to predict the noise reduction in barriers. Regarding the effect of buildings and water canals, various kinds of models were investigated to compare the effectiveness of different boundary barriers in real conditions from a listener’s perspective.
Results: The use of a single YA model could improve the performance of parallel barriers by 3.5 dB compared to that of a TS model. Moreover, by using a pair of barriers, no significant change was observed in the performance of the second barrier. However, by using parallel barriers along the surrounding buildings, the TD model improved the efficiency by 3 dB compared to the TS model. The rise in the frequency resulted in remarkable adverse effects on the barrier performance, such that the surrounding buildings at a distance of 8 m had a negative effect on the performance of the parallel barriers by almost 8.34 dB.
Conclusion: In general, by ignoring the buildings, the use of a pair of TZ barriers showed a higher performance. Meanwhile, by considering the buildings in the design model, the TD model was found to be optimum. Therefore, it can be concluded that choosing an ideal barrier only based on the noise behind it cannot indicate its behavioral and acoustic characteristics in a real environment.

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Introduction: The purpose of the current study was to predict the percentage of the sway index from the static balance point based on the anthropometric dimensions of construction workers.
Material and Methods: This descriptive-analytical study was conducted on 114 construction workers. First, the construction workers were asked to complete the demographic questionnaire and the inclusion criteria were determined. Then, the anthropometric dimensions were measured. Afterward, the static balance of participants was assessed with their open eyes and standing position using a Stabilometer device. The obtained data were analyzed using Pearson correlation and multiple linear regression.
Results: 29.8% of construction workers were in weak and very weak classes in terms of static balance. The Pearson and spearman’s correlation coefficient showed a significant relationship between age, weight, and sway index of individuals. In addition, multiple linear regression showed that age, weight, and foot surface of construction workers can predict the percentage of the sway index from the static balance point among construction workers.
Conclusion: The results of the current study indicated that demographic information such as age, anthropometric parameters of weight, and foot surface are effective factors on static balance in a healthy construction workers’ community with a normal body mass index.

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Introduction: Micro-perforated absorbents are one of the structures that are widely used nowadays. The sound absorption mechanism is performed by viscous energy losses in the cavities on the plate. In this study, the acoustic properties of non-flat perforated panels in oblique angle was investigated in numerical method.
Material and Methods: This paper examined the effect of the surface shape on the micro perforated absorber performance at low frequencies (less than 500 Hz). The three-dimensional finite element method was used to predict the absorption coefficient of this group of adsorbents. Also, the results obtained from the shaped absorbents were compared with the flat micro perforated ones. After validating the numerical results, six different designs were defined as the surface shape of the micro perforated plates in the COMSOL Multiphasic, Ver. 5.3a software
Results:  The results reflected the fact that the factor of the surface shape can be used as a contributing factor in lower frequencies. In general, the dented or concave shapes provide better outcomes than other flat designs and shapes and the convex or outward shapes bring the weakest results.
Conclusion: To explain this function, shaping creates a phase difference and angling the sound wave and creates a variable depth behind the micro-perforated plate. It also influences the reflection process which affect the absorption coefficient.

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Introduction: Methane is one of the most widely used gases in industries with a high flammability potential. This study aimed to evaluate the efficiency of ventilation systems installed on methane valve pits based on hazardous areas classification.
Material and Methods: This study was implemented in a steel industry in Qom Province in 2019. The tools used in this study were a DELTA OHM pitot tube (DO-2003) to measure wind speed, EPA Protocol for equipment leak emission estimates (U.S. Environmental Protection Agency) and IEC-60079-10 for evaluating the safety of ventilation of methane valve pits.
Results: The methane LELm was about 0.0334 kg/m³, and the volume of the release area was approximately VZ = 0.053 m³. The expected leak emissions were within the Vz < 0.1 m3 range. The ventilation system embedded on methane distribution pipelines was not effective for openings with diameters of more than 0.3 mm and the volume of gas inside the valve pits would quickly exceed high ventilation border which might lead to a dangerous accumulation of gas in the valve pits.
Conclusion: Given that a very small opening or leak in gas transmission valves may lead to the formation of an explosive atmosphere, it is essential to monitor methane before entering the valve pit area and performing any operations on valve pits.

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Introduction: Nearly half of occupational accidents in Iran occur in construction sites. Therefore, modeling of occupational accidents in these sites is one of the solutions to design safety strategies to reduce occupational accidents in the field of construction. This study was designed and conducted with the aim of modeling the cause-consequence of accidents in construction sites.
Material and Methods: This study was conducted based on a retrospective analysis of 10-year accident data (2010-2019) in Iranian construction sites in 2020. The main variable included the types of occupational accidents in construction sites. The study tool included accidents checklist as well as a detailed report of the studiedaccidents. The required data were collected based on a conceptual model designed to model the cause-consequence of accidents in the construction sites. Cause-consequence modeling of the studied accidents has been done based on the structural equation modeling and using IBM SPSS AMOS v. 22.0.
Results: The frequency of the studied accidents was 3854 accidents. The annual averages of AFR and ASR indices were 17.27 ± 8.54 and 322.42 ± 44.23 days, respectively. The results of cause-consequence modeling of these construction accidents showed that individual and occupational, safety training and risk assessment factors as well as variables related to these factors have a negative and significant relationship with the indicators of the construction accidents, and the factors of environmental conditions and unsafe acts and variables belonged to these factors have a positive and significant relationship with these indicators (p < 0.05).
Conclusion: The findings of the study revealed that the highest impact factors on accident indicators were related to safety training, risk assessment and unsafe acts and their variables. Therefore, the results of this modeling can help to design safety strategies in construction sites.

 

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Introduction: The manufacturing, service professions, and other occupations commonly require their employees to spend more than 2 hours of their workday in an upright position which can potentially cause temporary or permanent health effects. The objective of this study is to determine the effect of anti-fatigue mats on leg muscle discomfort and muscle activity due to prolonged standing.
Material and Methods: A total of 100 workers were involved in the study. The control and experimental group stood for 2 hours in a controlled room with or without the anti-fatigue mat while sorting an assortment of mixed items.  Borg’s scale questionnaire and EMG signals were used to monitor the muscle discomfort and activity of the respondents.
Results: The discomfort ratings and muscle activity in the experimental group were always at lower levels compared to the control group, which meant there was a reduction in mean perceived exertion rating for the knees, calves, and feet, i.e., 1.8, 2.5 and 2.6, respectively. The results showed that there was a statistically significant (P < 0.001) difference in the Borg’s scale of discomfort ratings and leg muscle activity between both groups.
Conclusion: The anti-fatigue mat can have a positive effect in preventing muscle discomfort and reduce muscle activity among the respondents during prolonged standing.

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Introduction: The study of noise has always been of interest to occupational health professionals as a harmful physical factor in the workplace. However, the psychological and psychoacoustic aspects of noise in the workplace have been less studied. This study has dealt with different colors of noise and their applications in psychoacoustics.
Material and Methods: This review study was conducted by searching the databases of Google Scholar, ProQuest, Science Direct, PubMed, and Scopus to extract the articles related to the research subject within a 50-year interval from 1970 to 2020.
Results: Based on the results of the present study, colored noises and white noise seem to have the potential to be used as acoustic stimuli to improve the sleep of employees, especially shift workers, to improve memory and attention, especially in jobs that require high care and attention. Colored noise and white noise have potential applications to improve cognitive function in different occupations to reduce the activity of the sympathetic nervous system and anxiety and stress, especially in jobs with high job stress. Also, these noises are helpful for people’s privacy, especially in the open workplace, for noise masking and noise control purposes, as well as for medicine and treatment of disorders such as tinnitus, ADHD, and hyperacusis.
Conclusion: Paying attention to the colors of noise and their psychoacoustic impacts shows us that the noise impacts are not limited to their undesirable and damaging effects. Instead, their positive and applied aspects should also note. Familiarity with such aspects and their introduction can identify the existing information gaps in this field and pave the way to fill them.

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Introduction: Studies show that in many cases, environmental hazardous agents such as heat, noise, as well as chemical pollutants cause adverse health effects through the mechanism of oxidative stress. This study has examined the effect of exposure to noise and whole-body vibration (WBV) on some parameters of oxidative stress (enzyme superoxide dismutase (SOD), total antioxidant capacity (TAC), and malondialdehyde (MDA)) of workers in a foundry industry.
Material and Methods: The workers were selected based on the calculations related to the sample size and taking into account the inclusion criteria as well as completing the informed consent form. The level of exposure to noise and WBV was measured according to ISO 9612 and ISO 2631, respectively. For each worker, the time-weighted average was calculated. The level of exposure of workers to the studied stressors was divided into three categories: low, medium, and high. The blood samples were taken from all participants between 7-9 am. Then, via ELISA method according to the protocol of the kit manufacturer, the samples were prepared and analyzed. Univariate analysis of variance was performed to determine the “effect size” of each physical stressors on the studied parameters.
Results: The mean levels of MDA, SOD, and TAC among participants were 22.48 (11.19) nmol / ml, 61.28 (10.97) U / ml, and 1.64 (0.90) mM, respectively. Among the exposure variables, noise had the largest effect on MDA level (B = 0.090), which was not statistically significant (P = 0.865). WBV had the largest effect on SOD level (B = -1.469) which was statistically significant (P = 0.016). None of the studied variables had a significant effect on the TAC level; however, among the exposure variables, the greatest effect was related to WBV (B = -0.077; P = 0.133).
Conclusion: The effect of noise on oxidative stress parameters was not statistically significant. The effect of whole-body vibration on oxidative stress parameters except SOD was not statistically significant. Noise and WBV had increasing effect on MDA and decreasing one on SOD and TAC levels.

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Introduction: Occupational fatigue is one of the harmful factors in many work environments, including health centers, which can have adverse effects on the health and safety of staff. This study was designed and conducted to determine the relationship between occupational fatigue and elements of the systems engineering model for patient safety in nurses.
Material and Methods: This descriptive correlational study was conducted with the participation of 457 nurses of Shahid Beheshti University of Medical Sciences in 2018. Dimensions of fatigue were assessed by a Multidimensional Fatigue Inventory (MFI) and Systems Engineering Initiative for Patient Safety (SEIPS) model’s elements using the SEIPS model’s questionnaire. Validity was examined using the Lawshe method; calculating Content Validity Ratio (CVR) and Content Validity Index (CVI) was approved through the confirmation of experts. Reliability was assessed using the intraclass correlation coefficient (ICC) and Cronbach’s alpha. Data analysis was performed using SPSS version 21
Results: The findings of this study indicated that the highest score of fatigue was related to the general fatigue dimension with an average of 12.86 and SD of 3.23, and the lowest score was related to the reduction of the motivation dimension with an average of 9.11 and SD of 3.66. In this study, no significant relationship was observed between demographic characteristics and fatigue dimensions, but a significant relationship was observed between the dimensions of fatigue with the element of organization, task, technology/tools, and physical environment.
Conclusion: The results of this study showed that fatigue in nurses was moderate, and the factors of the work system play a greater role in the occurrence of fatigue than demographic factors. Therefore, planning to improve the work system can help reduce fatigue in nurses.

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Introduction: Health workers, especially nurses, are facing a high risk of contracting the COVID-19 and consequent mental disorders such as stress, anxiety and depression. We aimed to study the relationship between anxiety, stress and the protective behavior of nurses during the Covid-19 pandemic.
Material and Methods: This cross-sectional study was conducted on nurses working in COVID -19 referral hospitals in Qazvin, Iran, in 2020. Out of 645 nurses working in two hospitals, 260 of them were selected randomly. Three questionnaires including demographic and contextual information, COVID-19 anxiety, stress and precautionary behaviors against COVID-19 were used. Descriptive statistical methods, Pearson correlation, t-test and one-way analysis of variance and binary logistic regression analysis were applied at 95% confidence interval.
Results: The prevalence of anxiety symptoms in nurses was 32.08%, the mean score of protective behavior was 18.45+5.66 and the maximum score was 22.06+4.7. The negative relationship between anxiety and nurses precautionary behavior) β=-0.36, P<0.05) and the significant effect of COVID-19 stress on nurses’ behavior) β=-0.22, P<0.05) were confirmed. Furthermore, adding stress as an interfering factor, affirmed the mediating role of stress in the relationship between anxiety and nurses’ precautionary behavior (β=-0.18, P<0.05). Nurses under 35 years of age were more likely (OR=1.62, P=0.004) to follow the protective rules; those with 6 to 10 years of hospital experience were respectively 32 times and 37 times more probable to use personnel protective equipment (PPE) (OR=1.32, P=0.002) .
Conclusion: The probability of effective use of PPE and observance of protective guidelines among nurses with severe and very severe anxiety levels was less than their counterparts. While in those with controlled level of stress level such obedience was much more probable. Therefore, all health service providers, need to develop supportive programs to emphasize on the promotion of employees’ mental health.

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Introduction: Complex sociotechnical systems, such as automotive industry, require a proper macro-ergonomic approach to design and implement the work system at micro-ergonomic level. The purpose of this study was to develop and validate effective macroeconomic factors to improve productivity, health and safety of employees in the automotive industry based on Holden & Karsh model.
Material and Methods: At the first step, relevant documents were reviewed, and then experts were interviewed to identify macro-ergonomic factors. The identified factors were categorized into four groups based on Holden & Karsh’s model. In the follow-up phase of the study, then, the content validity of the factors was calculated using Delphi technique in the form of an expert panel. Finally, validity acceptance was assessed using mean content validity index, and agreement between experts was evaluated using modified kappa coefficient
Results: 28 main factors were identified and categorized into four subgroups, including personnel, unit /department, organization and environment factors. 19 main factors were selected as the effective macro-ergonomic factors to improve employee’s productivity, health, and safety. The content validity index and the modified kappa coefficient were calculated as 0.901 and 0.90, respectively.
Conclusion: Macro-ergonomic factors identified in this study can be considered to improve employee’s productivity, health, and safety in the automotive industry. These factors can be used as specific context-based criteria for an ergonomic evaluation in the automotive industry, or even be generalized to other industries, organizations and companies.

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Introduction: Universities play a key role in creating a knowledge-based society and its sustainable development. Strategic planning by strategically analyses internal and external environments of the organization, forecast its future, identifying its strategic direction, and strengthening organizational structures, processes, and outcomes, creates and sustains competitive advantages. This study aimed to formulate a strategic plan for the Occupational Health Engineering (OHE) department of School of Public Health (SPH) at Tehran University of Medical Sciences (TUMS).
Material and Methods: In this participatory action research, a strategic planning committee was formed. The strategic planning committee used the strength, weakness, opportunity and threat (SWOT) matrix to evaluate the internal and external environments of the OHE department. Then, the mission, vision, values, goals and objectives of the OHE department were defined. Finally, the operational plan including actions to achieve the goals and objectives were formulated.
Results: Experienced professors and staff, specialized laboratories, professional journals, and high ranked postgraduate students were the most important strengths; and theoretical and non-practical courses, lack of educational protocols, poor communication with industries, lack of resources, and low motivation of employees were some of the weaknesses of the OHE department.  The support of senior managers of TUMS, industry liaison council at school and university, facilities of the university faculties, comprehensive research laboratories of the university, capacities of the private sector and increasing the demand for research in the industry were the opportunities. High inflation, political sanctions, the absence of consulting engineering companies and the uncertainty of research priorities of industries were important threats to the OHE department. Therefore, the OHE department is in a conservative strategic position. The strategic direction of the department, including the mission, vision, values and goals, until 2025 was determined. Improving the structures, working processes and performance of the occupational health department were determined as objectives and 81 actions were formulated to achieve these objectives.
Conclusion: The educational departments, schools and universities must have a strategic plan for progress. The strategic plan of the occupational health department of TUMS was formulated in line with the four-year plan of the university and coordinated with the operational plans of the educational, health and research deputies of TUMS and school of public Health. Proper implementation of this comprehensive and evidence-based strategic plan will improve the performance of the occupational health department.

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Introduction: One of the essential and critical elements for efficient and effective management of emergencies is anticipation and identification of possible types of emergencies. As such, a framework for anticipating and identifying emergencies was designed and tested in two process industries in the form of a case study.
Material and Methods: At first, methods for identifying emergency preparedness and their evaluation criteria were extracted and prioritized with a two-stage fuzzy approach. A fuzzy inference system was then used to calculate the weight of the experts’ opinions. To prioritize the methods, the inputs related to the second fuzzy system were estimated and the final score of the methods was calculated by entering the mentioned variables into the fuzzy system.
Results: The findings pertaining to the final ranking of the methods indicated that, “list of catastrophic accidents and near-misses of the organization’s lifespan”, “MIMAH” and “risk assessment and management” had the highest scores among the identified methods with the final scores of 0.754, 0.750 and 0.725, respectively.
Conclusion: Using this approach will help in more accurate identification of potential emergencies. Consequently, this will lead to the prevention of imposed damages caused by the situation as well as making the wrong investments by eliminating low-priority emergencies.

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Introduction: This study aims to determine the amount of hand-arm vibration transmitted from heavy electric destruction tools and the effect of using chisel with different lengths and shapes when demolishing concrete surfaces.
Material and Methods: To evaluate the magnitude of hand-arm vibration on the left and right handles of two powerful electric demolition hammers commonly applied in Iranian construction work and urban services, 323 measurements were made (RONIX and NEC). The demolition procedure was carried out by two experienced users on 49 concrete slabs of the same grade (20 C) with thicknesses of 10 and 15 cm while utilizing standard tools, such as hammers with two different chisel head shapes (flat and point) and lengths (40 and 60 cm). Utilizing two SVANTEK vibration meters concurrently on each hammer handle, measurement and evaluation were according to the ISO 5349:1, 2 procedures.
Results: The mean effective (frequency weighted root mean square) acceleration (awrms) for the Vector Sum Values (VSV) in the hammer handles were 15.71 m/s². The primary vibrational axis transmitted to the handle of tool was the vertical axis, at 13.60 m/s². When employing flat and point chisel, the mean awrms were 16.59 m/s² and 14.82 m/s², respectively. The difference between the results of 60 and 40 chisel was a little more than 2m/s2. The dominant and harmonic frequencies of the tools were generally in the range of 25 Hz to 80 Hz and 200 Hz to 400 Hz
Conclusion: The mean results generally indicated that point chisel with shorter lengths (40 cm) accelerates at a lower rate than flat chisel with longer lengths (60 cm). In the frequency range below 40 Hz, the RONIX hammer produced a larger acceleration than the NEC hammer indicating that the NEC hammer had a higher safety competitive advantage compared to the another hammer.