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Background and aims: Shift work and in particular night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue; it is also one of the major contributors of increasing the likelihood of risk of accidents in the industry. Better matching between individuals’ circadian rhythm and night shift and higher work performance can be achieved via designing an appropriate work shift pattern. The aim of this study was to compare the effect of two different rotating night shifts on information processing and alertness. Methods: This cross-sectional study conducted among 60 employees of the petrochemical industry control rooms with two different shift pattern consists of 7 consecutive nights (or 7 N) and 4 nights (4N). To assess the cognitive performance, n-back test, continuous performance test and simple reaction time test were employed. For assessing alertness the Karolinska Sleepiness Scale (KSS) were used. Results: Results from the both schedules indicated that the accuracy and speed of working memory and reaction time were significantly reduced (p0.05). Conclusion: The main duty of control room operators (CROs) at a petrochemical plant is checking hazardous processes which require appropriate alertness and cognitive performance. As a result, planning for appropriate working hours and suitable number of consecutive night shifts in a rotating shift system is a contribution to improving CROs performance and alertness and enhancing the safety.

Background: Spending a significant part of the daily in workplace has led to reduction in the time of rest and recreation of people. Therefore, considering the importance of the potential effect of mental work load on work ability, the present study was conducted to determine the relationship between mental workload and work ability in workers of a food industry. Methods: This cross-sectional study performed on 40 workers in a food industry in Qom province, Iran in 2017. Three demographic questionnaires, NASA-Tlx mental workload index and work ability index (WAI) were used for data collection. Finally, data were analyzed using SPSS software. Results: The results obtained from examining the relationship between work ability index and mental workload index in the studied industry showed high workload index score, however, there was no significant relationship between these two indexes (P = 0.07). results of regression analysis showed that only age of people has a significant relationship with the results of WAI. Conclusion: The mental workload index among workers of food industry was very high, which can be attributed to strict supervision due to the importance of food hygiene. High mental workload can affect human error and work efficiency of the worker.

Introduction: Low frequency sound is one of the most important sources of sound in the environment. Some individual differences such as extraversion, neuroticism, and sound sensitivity are factors that influence the effect of sound on cognitive functions. The purpose of this study was to investigate the effect of personality type (introversion/extraversion) on cognitive Performances in the presence of low frequency noise.Methods: This is an interventional study. The study population was Hamadan University of Medical Sciences students. 120 of them were selected through purposeful sampling (60 extraversion and 60 introverted) and entered the study. By simulating the real environment of each person, they were exposed to 50, 60 and 70 dB for 40 minutes. During the encounter, the cognitive Performances of the subjects were examined using the integrated visual auditory continuous performance test. Data were analyzed using SPSS20 software, independent t-test and ANOVA. Results: The results showed that low frequency noise negatively affects the components of cognitive Performances and decreases from 50 to 70 dB with increasing noise pressure (p

Introdaction: Musculoskeletal disorders MSDs is one of the most common causes of occupational injuries and disability in industrialized nations and developing countries. Musculoskeletal disorders have a high economic losses. . Musculoskeletal disorders not only impact on individuals, but also on organizations and community. Methods: This interventional study was conducted in the Tundish and Slide gate workstations of a steel company. To assess workers’ postures, the REBA and ManTRA technique were applied before and after the intervention. After data analysis, corrective engineering measures implemented in two mentioned workstations. Results: The findings showed a 63% and 64% reduction in risk level at Tandish and Slide Gate stations using the REBA method and a 47% and 56% reduction in ManTRA cumulative risk score at the Tandish and Slide Gate stations. Also data analysis showed that mean intensity of risk level score in the Tandish and Slide Gate stations using the REBA and ManTRA technique before and after the intervention were significant. Conclusions: The simultaneous use of the ManTRA and REBA methods is beneficial for occupations which the entire body is involved and more activity is manual as well as Occupations that work duration is important and limitation each method will be minimized using another method.

Background & objective: The present study was conducted to examine the risk factors associated with hand activity and to determine their cumulative effect on the development of upper extremity musculoskeletal disorders. Methods: The present clinical trial was conducted on 24 men and 6 women employed at a tea factory in Fuman in northern Iran. The human body map was used to assess the prevalence of musculoskeletal disorders and the HAL-TLV method was used for determining the risk levels. All the tests were analyzed at a significance level below 0.05. The Wilcoxon test was used to measure the likelihood of developing musculoskeletal disorders. The Kappa test was used to compare changes occurring in the HAL-TLV results before and after the intervention. The data obtained were then analyzed in SPSS-16. Results: The results obtained through the HAL-TLV method showed that, for the right hand, 7 participants were at a risk level below 0.56 (the safe zone), 10 at the risk level between 0.56 and 0.78 (the caution zone) and 13 at the risk level above 0.78 (the danger zone) before the intervention however, after the intervention, 27 participants fell at the safe zone, 2 at the caution zone and only 1 at the danger zone. The results obtained for the left hand showed that, before the intervention, 5 workers were at the safe zone, 12 at the caution zone and 13 at the danger zone after the intervention, however, 28 workers were at the safe zone, 1 at the caution zone and only 1 at the danger zone. Conclusion: The assessment of the risk factors associated with job-related musculoskeletal disorders and the design and implementation of technical, administrative and educational interventions can help reduce the prevalence of these disorders.

Background: In many workplaces, many factors exist as sources of stress such as environmental and physical factors, (eg, noise, overcrowding, poor lighting), human factors (conflict with another person), organizational factors (such as workload, Incorrect policy). if the person is not able to deal effectively with them, undergoing several physical and behavioral and psychological symptoms are happen. While prolonged stress may cause decreased job satisfaction and burnout that results is boredom, apathy, loss of effectiveness, fatigue, frustration, and even disappointment. Burnout in nursing profession, is a serious problem health care and has negative effects on clinical outcomes. The aim of this study was to assess the level of burnout ,job demand - control and also The relationship between burnout and job demand - control among nurses. Methods: in this cross- sectional study, 415 randomly selected nurses from hospital of Hamedan university of medical sciences participated. The Persian version of job content questionnaire(P-JCQ) and maslach burnout inventory used for data collection. Using SPSS16 software , descriptive statistics and multiple logestic regression and x2 test were applied for data analysis. Results: the finding of present study indicated that burnout levels were relatively high. Mean and standard deviation score for Emotional exhaustion, Depersonalization and Reduced personal accomplishment dimensions were (25.3±12.42),(5.91±5.1),(33.30±9.59) respectively. About 51% of nurses reported high job demands and 57% of them had high control over their tasks. About 30% of nurses reported that their job were active, 21% passive, 22% high strain and 27% low strain. And غير فعال job supported reduced personal accomplishment dimension of burnout (OR=0.433). Conclusion: Based on the results of the study should be stated that if job control and psychological job demand were high, nurses will not be prone to burnout. And also occurrence of burnout in reduced personal accomplishment dimension among nurses who reported their job had low psychosocial demand and low control, was more than others.

Background and Objectives: One important topic in work physiology is considering maximum aerobic power) VO 2max (, which is one of the most important decision-making factors in individual fitness and in prevention of premature aging, and can play a significant role in selecting appropriate workforce. This study was done with the objective of investigating the effect of gender, ethnicity, anthropometric dimensions, physical activity, and smoking on VO 2max level in students of Hamadan University of medical sciences. Methods: In this descriptive-applied study, 160 students were randomly selected, and after collecting demographic information using written questionnaires, their anthropometric characteristics were measured by a stadiometer. Then, VO 2max of the subjects was measured using treadmill and Strand graph. The data were analyzed by nonparametric statistical tests of Mann-Whitney and Pearson’s correlation coefficients . Results: In this research, 41.9% of subjects of the sample were male and 58.1% were female. Also, there was a significant correlation between VO 2max and the variables of gender and height (p

Background and Aim: Casting workers are facing with ergonomics hazards such as overload in Manual Material Handling (MMH) tasks which expose them to risk of work-related musculoskeletal disorders (WMSDs). There are several methods to determine acceptable weight among which, Snook table is one of the oldest one. The aim of the study was to assess prevalence of WMSDs and to investigate MMH tasks by Snook tables among casting workers. Materials and methods: This cross-sectional study was conducted among 50 casting workers occupying in all of the five MMH tasks including lifting, lowering, carrying, pushing and pulling. Nordic Musculoskeletal Questionnaire (NMQ) and concise Snook tables were used to gathering required data. Statistical analyses were done using SPSS 16.0. Results: The most common musculoskeletal disorders in one year prior to the study were hand wrist disorders (84%), low back pain (74%) and neck disorders (72%), respectively. The Snook tables results indicated that significant differences were found between acceptable weights and workers exerted load in lifting and lowering tasks (p

Introduction & Objective: Noise is one of the most important harmful agents in work environment. In spit of industrial improvements, exposure with over permissible limit of noise is counted as one of the health complication of workers. In Iran, do not exact information of the absorption coefficient of acoustic materials. Iranian manufacturer have not laboratory for measured of sound absorbance of their products, therefore using of sound absorber is limited for noise control in industrial and non industrial constructions. The goal of this study was to design an impedance tube based on pressure method for measurement of the sound absorption coefficient of acoustic materials. Materials & Methods: In this study designing of measuring system and method of calculation of sound absorption based on a available equipment and relatively easy for measurement of the sound absorption coefficient related to ISO10534-1 was performed. Measuring system consist of heavy asbestos tube, a pure tone sound generator, calibrated sound level meter for measuring of some commonly of sound absorber materials was used. Results: In this study sound absorption coefficient of 23 types of available acoustic material in Iran was tested. Reliability of results by three repeat of measurement was tested. Results showed that the standard deviation of sound absorption coefficient of study materials was smaller than 3×10-2. Conclusion: The present study performed a necessary technology of designing and producing of impedance tube for determining of acoustical materials absorption coefficient in Iran.

Background: shift work is associated with both sleepiness and reduced performance. The aim of this study was to examine cognitive performance, sleepiness, and sleep quality among petrochemical control room shift workers. Method: Sixty shift workers participated in this study. Cognitive performance was evaluated using the objective test such as continuous performance test, n-back test, and simple reaction time test; sleepiness scale was measured using the subjective Karolinska Sleepiness Scale (KSS); and sleep quality was assessed using Pittsburgh Sleep Quality Index (PSQI) questionnaire. ANCOVA, t-test, and repeated-measures ANOVA was used for statistical analyses, and the significance level was set at 'p' < .05. Results: All variables related to cognitive performance, except for omission error, significantly decreased at the end of both day and night shifts ('p' < .0001). There were also significant differences between the day and night shifts in terms of the variables of omission error ('p' < .027) and commission error ('p' < .036). A significant difference was also observed between daily and nightly trends of sleepiness ('p' < .0001) so that sleepiness was higher for the night shift. Participants had low sleep quality on both day and night shifts, and there were significant differences between the day and night shifts in terms of subjective sleep quality and quantity ('p' < .01). Conclusion: Long working hours per shift result in fatigue, irregularities in the circadian rhythm and the cycle of sleep, induced cognitive performance decline at the end of both day and night shifts and increased sleepiness in night shift. It, thus, seems necessary to take ergonomic measures such as planning for more appropriate shift work and reducing working hours.

Aims: This study was done to evaluate the effect of three kinds of respiratory protective equipments (RPE) on the heart rate in light, moderate and heavy workload. Materials and Methods: This study was performed on eleven healthy university students (male) under controlled thermal conditions in a climatic chamber. The mean (SD) of age, height and body mass index (BMI) were 24.1 (2.34) years, 172 (4.2) cm and 22.4 (1.1) Kg/m2, respectively. Subjects were participated in the four intermittent exercises experiments (without RPE, valve, half-face and full-face) on a treadmill in light, moderate and heavy workload. Duration of light, moderate and heavy activities was 30, 30 and 20 min, respectively. Heart rate was recorded every 5 min. Results: The mean of heart rate in 11 subjects for without RPE trial in light, moderate and high workload was 93.5±13.1, 109.7±18.1 and 119.6±25.8 beats per min (bpm), for valve RPE was 102.8±9.7, 116.7±16.0 and 132.1±23.2 bpm, for half-face RPE was 102.4±11.42, 117.3±15.8 and 132.0±23.1 bpm and for full-face RPE was 109.3±14.7, 125±17.4 and 140.1±23.1 bpm, respectively. In three work load, significant differences between the mean of heart rate by using three kinds of RPE trials showed with without RPE trial were observed (P-value < 0.001). Also, mean of heart rate in three workload levels when using full-face RPE trial was significantly higher than valve and half-face RPE trials. In the valve and half-face RPE trials, significant differences were not detected Conclusions: The results demonstrated that heart rate were significantly increased with wearing of three kinds of RPE. Full-face RPE have a higher effect on increasing heart rate than half-face RPE.