Mohammad Babamiri, Rashid Haidari Moghaddam, Fakhrodin Ghasemi, Mohammad Ghaffari, Mahdi Razee, Khadijeh Bandeh Ellahi, Alireza Mortezapour,
Volume 6, Issue 3 (10-2018)
Abstract
Background and Objectives: Nowadays, the use of the Internet among students has become widespread. Addiction to virtual networks and online games can have various consequences, including the threat of musculoskeletal system in these people. The purpose of this study was to determine the effect of addiction to social networks and online games on students’ wrist pain.
Methods: This study was conducted among 665 students. Data collection was done through three questionnaires of problematic use of online games, social networking addiction and Nordic musculoskeletal disorders. Data were compared by Chi-square and independent T-test and finally, logistic regression model was presented at a significant level of 0.05.
Results: The results showed that social network and online game addiction can increase the risk of pain in the wrists. Sex had a significant impact in the effect of social network addiction on pain in the wrist. Other results of the present study are the not significant differences in the age and level of education of the participants in the prevalence of wrist pain.
Conclusion: It can be stated that there is a likelihood of a relationship between social network and online game addiction with wrist pain. Therefore, due to high prevalence of this addiction among students, appropriate planning should be taken to reduce complications and injuries, especially in the wrist area of them.
Afshin Marzban, Abdollah Hayati,
Volume 6, Issue 3 (10-2018)
Abstract
Background and Objectives: Fruit harvesting operation, one of the most important operations related to date palm production, is performed manually. Manual date palm harvest suffers from frequent occupational risk factors due to excessive need of physical work resulting in work related illness and productivity reduction.
Methods: Present study was undertaken with recruiting twenty three harvest workers to evaluate and compare upper-trunk (consisting of work tasks: climbing, cutting the bunch, and descending) and bottom-trunk operations regarding physiological (heart rate and heart rate ratio) and physical (body pain) strains to identify onerous critical operations to address with simple and inexpensive interventions by future attempts.
Results: Upper trunk operation posed a more physiological strain as heart rate (29.4%) and heart rate ratio (177.8%) higher than bottom trunk operation. Body pain was self-reported by the upper trunk workers in low back and sole, and by lower trunk workers in low back.
Conclusion: The upper trunk operation was the onerous critical operation in manual date palm harvest, and climbing was the most critical work task in upper trunk operation. Climbing causes the highest physiological strain because workers moved in converse of gravity force, whereas descending led to lowest one because of moving in the similar direction with gravity.
Zivar Sabaghinejad, Abdolkazem Neisi, Somaye Parvin,
Volume 6, Issue 3 (10-2018)
Abstract
Background & Objectives: Each organization needs to provide an environment that is smooth, tensile, comfortable and affordable with appropriate physical and emotional conditions for each employee, a safe and relaxed working environment, so that they can work best with a sense of job satisfaction. The present study examines the ergonomic conditions of libraries in public universities in Ahwaz and its impact on job satisfaction and librarians.
Methods: This research is descriptive and has been surveyed. The population of the study consisted of 84 librarians of Shahid Chamran Universities and Ahvaz Jundishapur University of Medical Sciences who participated in the study census. To evaluate ergonomic conditions, a questionnaire was extracted from ergotools software, job satisfaction survey from Arenson et al. Scale and job evaluation questionnaire by Faraj Pahloo, Nooshin Fard and Hasanzadeh. Relationships between research variables were investigated using structural equation modeling.
Results: The results showed that there is a direct, positive and significant relationship between ergonomic conditions and job satisfaction, job satisfaction and job performance, and ergonomic conditions and job performance. There is also a positive and significant indirect relationship between ergonomic conditions and job performance due to job satisfaction.
Conclusion: All relationships between the variables examined were confirmed. Therefore, ergonomic conditions are effective both directly and through the job satisfaction of librarians’ job performance. Considering the positive and direct relationship, it can be said that the librarians of the public universities’ libraries of Ahwaz are pleased with better ergonomic conditions and show better job performance.
Elham Ahmadi Kivanani, Mostafa Pouyakian, Abbass Alipour,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: Accurate measurement of the employees’ satisfaction with their office chairs can provide valid feedback on the chair design quality for the manufacturers and researchers. This study aims to design a valid and psychometrically evaluated questionnaire for measuring satisfaction with office chairs.
Methods: Through studying the two main documents about chair ergonomics including Iranian office chair standard No. 11388-1 and a valid Persian questionnaire on satisfaction with educational chairs (Mirmohammadi et al.), the initial 39-item office chair satisfaction questionnaire has been developed. Then face and content validity of the questionnaire have been checked out using qualitative and quantitative approach. Quantitative face validity was analyzed using impact score method. Content Validity Index (CVI) and Content Validity Ratio (CVR) have been used for quantitative content validity analysis. In order to analyze the questionnaire’s reliability, two methods including the internal consistency and constancy have been applied. To measure the internal consistency, α-Cronbach (alpha coefficient) and to evaluate constancy (test-retest) have been employed. Also, the receiver operating characteristic (ROC) curve was utilized for specifying its sensitivity, specificity, and cut-off point. The data was analyzed by SPSS 21 and Stata V.14
Results: Mean (CVR) and (CVI) of final questionnaire have been calculated as 0.93 and 0.95, respectively. Questionnaire’s α-Cronbach coefficient has been gained 0.8. Kappa coefficient (for inter-rater agreement) has showed high score (0.91) in the test-retest results, indicating high correlation and good constancy of the questionnaire. In the ROC, the cut-off point was reported as 75.5 with the sensitivity and specificity of 86.2 and 100, respectively, and area under the ROC curve at this cut-off point was 0.96.
Conclusion: The final 34-item questionnaire has exhibited acceptable reliability and validity for measuring satisfaction level of office chairs.
Fakhradin Ghasemi, Kamran Gholamizadeh, Amin Doosti-Irani, Rahmani Ramin,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: Upper extremities are very vulnerable to work-related musculoskeletal disorders and selecting the best technique for assessing their exposure to ergonomic risk factors is of pivotal importance. This study aimed to compare two techniques of SI and ACGIH-HAL and assess their relationship with carpal tunnel syndrome (CTS) among butchers.
Methods: The study population was all butchers in Hamadan, Iran. After observing the activities, the assessments were conducted using both techniques. The severity of CTS syndromes was assessed using Boston questionnaire. The agreement between the techniques was investigated using Kappa coefficient. The association between the risk levels obtained from the techniques with the severity of CTS syndromes were assessed by regression analysis and fixing the effect of personal factors such as age, body mass index, and wrist ratio index.
Results: a total number of 152 butchers were evaluated. SI and ACGIH-HAL techniques respectively recognized 76 and 102 cases as low risk (agreement in 69 cases), 40 and 27 cases as moderate risk (agreement in 8 cases), and 36 and 23 cases as high risk (agreement in 18 cases). The Kappa coefficient between two techniques was 0.36 (P<0.001). By fixing the effects of age, body mass index, and wrist ratio index, both techniques had significant association with the severity of CTS syndromes. However, the association between SI and severity of CTS syndrome was higher than that of ACGIH-HAL.
Conclusion: SI had a higher estimate of risk than ACGIH-HAL. It seems that the predictive ability of SI for the severity of CTS syndrome is better than that of ACGIH-HAL.
Mehdi Ganji, Milad Karimi, Behnoush Bahari,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: Due to the necessity of the proper driver packaging, setting parameters for the driver to achieve the highest ergonomics of the driver has a great importance. The range of variations in some parameters of the package is wide, and the correct selection of the packaging parameters until to achieve driver’s ergonomics position, requires some tests.
Methods: In this study, using the MINITAB16 software and using these parameters, several driving simulation were performed using the DHM (Digital human modeling) and DOE (Design of experiment) tools. Hence, for the C segment vehicles, the range of all driver’s package parameters, such as seat height, steering angle etc., was extracted using the A2MAC1 site, and was considered as the basis for the input parameter. According to the proposed tests by MINITAB16 software, the driver’s comfort level was evaluated based on the PORTER (1998) criteria.
Results: The seat height and also vertical and horizontal distances of the steering wheel to the accelerator heel point have the greatest impact on the driver’s ergonomics. Also, due to the high correlation between some of the parameters of the package and the ergonomics outputs of the body while driving, predictive equations were presented in this regard.
Conclusion: The results are the optimal model for ergonomic driving position. The most influential parameters of the driver’s package are ergonomically known and using the ANOVA (Analysis of variance), mathematical predictor models were presented.
Dr Ehsanollah Habibi, Emad Mirsalimi, Faezeh Darabi, Kamran Ebrahimi,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: This study focused on lifting drill rods. Drilling is a repetitive and heavy mining operation with a high incidence and severity of musculoskeletal injuries. The purpose of this study was to examine how to lift a vertical drill bit (1.61m and 35kg in height) using two types of rod height and four feet positions, and finally compare them with the Lifting Index (LI).
Methods: Seven workers participated in this study. Each person raised a rod and held it vertically. Reflective markers were installed on each person, and from three cameras and an Ergo-meter plate for record forces and Movement of the limbs. In this case, four positions of the foot and pressures on the lower back were Investigated (position0=to the rod, position45=diagonally to the rod, position90=right side of the bar and free posture). In addition, two positions of the height of the rod were Investigated, at the first, the end of rod was on the ground (height of the rod was 83 m), and in the following the end of rod was on the Basket with height 20cm (rod height of 1.03 m).
Results: The Lifting Index (LI) for each person was equal to 1.4 in the NIOSH lifting equation. It was found that the vertical height of the rod had the greatest effect at the load on the lower back. Some workers use techniques that endure less pressure on their waist.
Conclusion: Finally, it was found that the asymmetric loading Condition (90 ° angle) was the worst case compared to the Lifting index and NIOSH standard.
Dr Siavash Etemadi Nejad, Saed Ahmadi Ganjeh, Dr Jamshid Yazdani Charati, Dr Seyed Esmaeil Hoseininejad,
Volume 6, Issue 4 (3-2019)
Abstract
Introduction: The aim of this study was to evaluate the effect of unstable shoes on lower limb kinetic parameters of walking in healthy male students with different geometric shapes. Today, various shoes have been developed to reduce the effects of injury parameters and improve performance parameters for walking.
Methods: 20 of the healthy male lambs were selected 178.96 ± 3.92 cm, 27 ± 3 years old, 73.99 ± 6.6 kg and 42 (EU) number, in four position, domestic production unstable shoes , foreign Similar unstable shoes, regular control shoes, and barefoot, The Kinetic parameters associated with Lower limbs was evaluated by force plate while walking. To examine the significant statistical differences between dependent variables between the four conditions of foot cover, the general linear model and the analysis of variance with repeated data and / or Friedman in the case of normalization of data in the alpha level of 5% using software version 23 SPSS was used.
Results: In relation to the kenetic parameters of the lower extremity, there was no change in the peak Postereior Force and the peak active force in the case when there was a significant change in the peak passive force and peak anterior Force and and the free movment and loading rate.
Conculosion: The results indicate to the domestic production unstable shoes inefficiency in reducing the damage and increasing the comfort of the lower limbs.
Maryam Azhdardor, Shahnaz Tabatabaei,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: Musculoskeletal disorders is a working environmental damage that affects staff’s quality of life; in addition to high costs, it reduces physical, mental and social heath, and thus reduces the efficiency of staff. This study aimed to investigate the relation between musculoskeletal disorders and quality of life in selected hospital’s staff.
Methods: In this descriptive-analytical study, the study population included all the employees (n=770) of Kordkuy Heart Hospital and Khatam al-Anbia Hospital of Gonbad Kavus, Golestan Province, Iran. The standard sample size of 300 employees (150 Kurdkuy and 150 Gonbad Kavus) from different occupational groups were randomly selected by stratified sampling. To collect the data, a demographic information form, the Nordic Musculoskeletal Questionnaire, and the Lancashire quality of life profile were used. Independent t-test and Backward stepwise were run in SPSS 22.
Results: A significant relationship was observed between musculoskeletal disorders and musculoskeletal disorders (general) in staff. A significant relationship was observed between gender and musculoskeletal disorders. Between quality of life at different levels and demographic variables, a significant difference was observed between the average quality of life with emphasis on gender and body mass index.
Conclusion: According to the results, gender and working shifts were effective in risk of musculoskeletal pains and can have a negative effect on staff’s quality of life. Thereby optimizing work conditions has a considerable effect on quality of life.
Mahnaz Shakerian, Dr Alireza Choobineh, Dr Mehdi Jahangiri, Dr Moslem Alimohammadlou, Dr Mohammad Nami,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: The recognition of a system failure causes and their related factors are considered as the most important factor in preventing accident occurrence in different organizations including industries. Human error is a known important factor in unpredictable events of which cognitive factors are the most influential ones. The purpose of this study was to introduce a new model for individual cognitive factors influencing human error as well as determining the interactions between the factors and their intensity using DEMATEL approach.
Methods: First a qualitative study was performed in order to identify and elicit the individual cognitive factors influencing human error among the workers of different industries. To ensure the adequacy and comprehensiveness of the elicited factors, then, the experts’ opinion was applied. DEMATEL method was used for understanding the interactions among the individual cognitive factors influencing human error. Finally, using these relationships, a new model of the study was proposed.
Results: Calculating D-R and D+R relating to the factors in terms of being cause or effect factor, D-R was -1.213 for C5 as the highest negative value, and D+R was 2.294 for the same factor (C5). Also, threshold level was calculated as 0.087 in the current study
Conclusion: In this study, the factors of failure in problem solving and decision making (C5) and difficulty in predicting possible hazards in the workplace are effects and the other factors were the cause factors. The factor of C5 was the highest interactive factor.
Zahra Vahedi, Dr Adel Mazlomi, Dr Ali Sharifnezhad, Dr Kamal Azam,
Volume 6, Issue 4 (3-2019)
Abstract
Background and Objectives: In the last decade, the smartphones have become one of the most popular technologies around the world. Due to the multi-functional use of smartphones, the technology users spend long hours using it.
Methods: This was a semi-experimental and experimental study. In the first section, 98 students entered the semi-experimental part and completed demographic and body map questionnaires before starting the study. They were asked to perform their duties with their phone for 20 minutes and then complete the body map questionnaire again. In the second part of this study, 12 women from the first group participated in the experimental study to assess the neck flexion using the motion capture. SPSS 24 was used for statistical analysis.
Results: Searching the Internet and sending texts were the most common tasks among the participants in this study. The use of cell phone caused an increase in pain and discomfort in the neck, shoulder, thumb, thenar. The results of the study showed that there is a significant association between sitting posture and high level of neck forward flexion. Furthermore, neck flexion increased during typing while both hands holding the handset.
Conclusion: Smartphone users have had repetitive motions in fixed postures for a long time, and these factors are thought to increase the likelihood of musculoskeletal disorders.
Rahmkhoda Javadi, Mohsen Rasouli, Jafar Hasani,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: Quality of work life is one of the most important factors in promotion of teachers and having them continue their jobs. This study aimed at designing and evaluating a questionnaire for teachers’ work life quality.
Methods: In this research, a sequential exploratory approach (instrument editing model) was used and in the qualitative stage, a semi-structured interview method was used to determine the quality of life of teachers. In the qualitative stage, indices of work life quality were identified using semi-structured interviews with 12 teachers (9 men and 3 women) of Karaj city (2014-2015 educational year) selected through purposive sampling method. The qualitative data was analyzed using Straus and Corbin method. Subsequently, a questionnaire of teachers’ working life quality was constructed based on these indices and was validiated in the quantitative stage.
Results: Content validity was confirmed by five experts using content validity index. A sample of 760 (387women) teachers selected through multistage cluster sampling were handed out two questionnaires including a researcher-made questionnaire of teachers quality of working life and Walton (1973) quality of work life questionnaire. Construct validity of the research-made questionnaire was examined using exploratory factor analysis. Eight factors were extracted and confirmed through confirmatory factor analysis. Fit indices of model indicate compliance. Convergent validity was confirmed by its correlation with the quality of work life questionnaire (P<0.01). Reliability was confirmed by calculating Cronbach’s alpha coefficient (0/74-0/88).
Conclusion: The results of the study indicated that the researcher-made questionnaire with regard to its design in the job context of Iranian teachers, with 54 items, is an appropriate tool for assessing the quality of their working life.
Dr Kimia Mirkamali, Dr Arman Ahmadizad, Saeed Kazemzadeh, Maryam Varmaghani,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: The progress and rebound of organizations depends on their productivity. Many factors affect the organization’s productivity; identifying these factors the organization’s deterrence can be prevented. In this study, the relationship between job burnout and employee productivity has been investigated.
Methods: This research is applied and its statistical population is 1265 people in Shariati and Kharazi hospitals. 294 of these employees were selected by Convenience sampling method considering the Cochran formula. Data was collected using the Maslach Burnout Standard Questionnaire and Hersey and Goldsmith Human Resources productivity Standard Questionnaire. Pearson correlation test and SPSS18 was used to analyze the data.
Results: The results of data analysis showed that burnout, emotional exhaustion, depersonalization and reduced personal accomplishment with -0.82, -0.86, -0.83 and -0.85 correlation values, respectively, have a reverse and meaningful relationship with employee productivity of Shariati and kharazmi Hospitals employees.
Conclusion: Since the results showed that burnout and its dimensions have a significant relationship with productivity of Shariati and Kharazmi Hospitals in Isfahan, it is necessary for organizations to apply measures to reduce the feeling of burnout in the staff. The results of this study are consistent with the results of other studies. At the end of the study, were presented several research proposals based on the results of the study.
Mehdi Shabani Arani, Dr Shahnaz Tabatabaei, Dr Nabiolah Mansouri,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: One of the most important causes of industrial incidents, of which 90% is related to human factors, is to refuse to accept errors because of fear of blaming and concealing them. In the present study, the relationship between just culture and safety culture was investigated in one of the industrial sections of Tehran.
Methods: The research was descriptive-analytic and conducted as a cross-sectional study. Out of 320 a sample of 181 staff who worked at the operational and administrative sections were selected in an accessible manner. The research instruments consisted of questionnaires of personal and occupational information, just culture and safety culture. Data was analyzed using, Pearson correlation coefficient and multivariate regression by SPSS22 software.
Results: The relationship between different dimensions of safety culture and just culture is 0.84 (P<0.001). The power prediction of safety culture is based on different dimensions of the just culture 0.70 (P<0.05). Between different dimensions of safety culture, the level of information exchange, education and management commitment are most closely related to mean of just culture. Also, the level of information exchange is the highest and safety priority shows the least link with the just culture. Therefore, the exchange of information can lead to a continuous improvement of the just culture.
Conclusion: Evaluating the just culture, the safety culture of the employees of the organization can be predicted with a high level of certainty, which shows the direct relationship between the just culture and the safety culture. So, increasing the just culture directly contributes to the development of the safety culture.
Ali Arabian, Seyed Abolfazl Zakerian,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: The use of new technologies, particularly mobile phones, is drastically growing on a daily basis. The usability of mobile phones can be determined for different age groups in order to reach a balanced development plan with respect to this technology. The present study aimed to investigate and compare the usability of touch-screen and button cell phones among Iranian elderly users, with respect to objective performance and perceived usability.
Methods: In this cross-sectional study, 20 elders (50% female) with an average age of were selected by simple random sampling method to measure the usability of touch-screen and button cell phones. In order to assess the objective performance of how elders work with cell phones, tests were conducted including items like typing speed, number of typing errors, taking photo, creating new contacts, and sending text messages. Perceived usability was obtained using a questionnaire of cell phone usability. Furthermore, muscle pressure and mental work load during cell phone use were evaluated by Borg CR10 and NASA-TLX questionnaires, respectively. Data were analyzed conducting statistical analysis tests of T-test and Mann-Whitney by SPSS24 software.
Results: Results revealed that the average typing speed and typing errors in touch-screen cell phones are larger than that in button cell phones. Moreover, the average of perceived usability in touch-screen cell phones (5.8) is higher than that in button cell phones (4.3). Pearson correlation coefficient showed an inverse relationship (-0.3) between perceived usability and mental work load obtained in both types of the cell phones. Findings showed that the maximum perceived muscle pressure when working with a cell phone is felt in the neck area.
Conclusion: According to the obtained results, touch-screen cellphones are suggested for those elders who type more and button cell phones are recommended for those who use the cell phone menu more frequently, namely taking photo, calling, internet, and so forth.
Dr Adel Mazloumi, Leila Hajizadeh, Vafa Feyzi,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: These days, due to increasing of old people’s population, elderly is a world widely issue. According to World Health Organization (WHO) people older than 60 years old are called elderly. Becoming old leads to decline in physical ability and increase in physical limitations and therefore there is a need for matching the environment with elderly users. The aim of this study is to develop and valid of check lists for screening the environment risk factor and assessing of elderly functional ability for environment and tools designing.
Methods: Present study is an analytical and descriptive study, which was performed in 20 houses for old people in Lar city. Data collection was done on existing articles and checklists, and also interview and observation with elderly. Existing checklist was evaluated in validity and reliability with high acceptable level.
Results: Based on findings of this study, height of mirror of wash-stand, height of wash-stand, dimension of yard and doorway was considered in ergonomics risk factors checklist. Items like opening door personally was involved in Functional Ability checklist. Validity score was lower than 0.78.
Conclusion: According to findings, it’s necessary to consider elderly limitations and ability in designing environment and tools in order to resolve their problems and increase their quality of life.
Fatemeh Chahraghran, Shahnaz Tabatabaei,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: Considering that musculoskeletal disorders and occupational stress are one of the most important reasons for disability, physical and mental problems in the staff, the study of their causes is of great importance. Therefore, this study was conducted to investigate the relationship between ergonomic risk level and job stress in employees of a food production plant.
Methods: This was a descriptive-analytic research. It was carried out for a sample of 200 employees in the production and packaging of a food production plant in 2018. The QEC method was used to determine the ergonomic risk level and the OSPU questionnaire was used to measure occupational stress. Descriptive and inferential statistics (T and F tests) were used to analyze the data.
Results: The findings showed that the level of ergonomic risk in the neck, shoulders and wrists is in the unfavorable situation. Workstations will need to be repaired in the near future. There is a significant relationship between the level of ergonomic risk and the demographic variables of gender and education with job stress.
Conclusion: Unfavorable ergonomic status of workstations in the food factory has increased the worker’s stress in the manufacturing and packaging sectors. Therefore, proper design of workstations and consideration of ergonomic principles are effective in improving the physical and mental health of employees.
Iraj Alimohammad, Reza Pourbabaki, Kazem Rahmani, Mehrdad Souri, Fakhradin Ahmadi Kanrash,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: Studies have shown the effect of smoking on mental and cognitive performance of the individuals who need to concentrate on their work. The present study aimed to investigate the effect of smoking on cognitive performance of the automotive industry workers.
Methods: In this case-control study conducted in 2018, 280 automotive industry workers were selected through the simple random sampling and then assigned to two groups of smokers (100 cases) and non-smokers (180 controls). All the subjects were selected from the environments with the sound levels of 82 to 88 dB. The workers’ cognitive performance was also tested using the CPT, Stroop and Tower of London tests.
Results: The mean age of the case group was 36/02 (3/7) and that of the control group was 36/25 (3/65) years. The results showed that the scores of the TOL test in the case group (smokers) were lower than those of the non-smokers (OR=0/903, P<0.01), and other items of the TOL test had no significant relationship with the individuals’ smoking status (P>0/05). The Stroop and continuous performance tests also had a significant relationship with the individuals’ smoking status in terms of the number of correct responses and the response time as well as interference (P<0.01). Other items had no relationship with the individuals’ smoking status (P>0/05).
Conclusion: The results of this study showed that the use of cigarettes and nicotine substances significantly decreased the workers’ mental and intellectual performance, and smokers were more likely to suffer from concentration interference, low brain processing speed in decision-making, and low precision at work, compared to non-smokers.
Fakhradin Ahmadi Kanrash, Iraj Alimohammad, Jamileh Abolaghasemi, Kazem Rahmani,
Volume 7, Issue 1 (5-2019)
Abstract
Background and Objectives: Noise pollution is one of the most harmful physical factors in working environments in developed and developing countries, which has significant impacts on the workers’ quality of life. The aim of this study was to investigate mental and physiological effects of chronic exposure to noise.
Methods: This is a cross-sectional study carried out randomly in 2018 on 250 workers in the automotive Industry. To measure the subjects’ aggression and annoyance levels, the Buss and Perry’s Aggression Questionnaire was used as well as an annoyance questionnaire. In this study, blood pressure measurement was also done using ALPK2 mercuric pressure gauge.
Results: The results showed that there was a significant difference in the systolic and diastolic blood pressure and noise annoyance in the groups with a lower-than-85 and higher-than-85 dB sound pressure levels (P<0.001). Besides, the results of multivariate regression showed that the annoyance level and sound pressure level had a significant relationship with the workers’ blood pressure (P<0.01). Also, there was a significant correlation between aggression components and sound pressure level (P<0.01).
Conclusion: The results of this study clearly showed that chronic exposure to noise in work environments was associated with psychological and physiological changes, such as increased blood pressure and aggression levels. Hence, implementation of preventive programs can help reduce the incidence of the psychological and physiological disorders.
Mahnaz Ahmadlu, Mostafa Pouyakian, Mohammad Ranjbarian, Soheila Khodakarim,
Volume 7, Issue 2 (9-2019)
Abstract
Background and Objectives: There are various models of socket wrench in the market varying in the length and diameter of handle and weight. Each of these features alone can modify the force applied by the hand and affect how comfortable the user is. The purpose of this study was to investigate the relationship between dimensional properties and weight of several models of socket wrench with their usability index score.
Methods: 58 male technicians from maintenance units of Shahid Beheshti University of Medical Sciences performed the task of opening 12 bolts with 8 N/m of torque using 6 models of socket wrench with different physical properties. The sample size was selected based on proposed figures for usability studies. The System Usability Index (SUS) validated questionnaire was used to determine the usability score of each model after the experiment. The study was conducted in 2017. SPSS 21 was used for data analysis.
Results: The results showed that there was a significant relationship between usability index score and dimensional properties and weight of wrenches (P<0.001). Wrench models with longer handle and diameter size close to optimum range of diameter of hand tools for male users had a higher usability score, and participants reported a better test experience with these models.
Conclusion: Using the System Usability Index (SUS Questionnaire) to measure the quality of human-centered design of hand tools is a good way to evaluate and select the hand tools that are widely used by technical staff. The results of this study are valid for short-term applications of wrenches. However, for long time activities, epidemiological and physiological evidences such as EMG should also be used.
