Journal of Health and Safety at Work

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Introduction: Electromagnetic field emitted by laptops are known as extremely low frequency (ELF) Waves. The aim of this study was to investigate the intensity of electric and magnetic field with extremely low frequency emitted by common laptops.

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Material and Method: Intensity of electric and magnetic field were measured on four sides of 40 common by used laptop at the distance of 30, 60 and 90 cm. Measurements ere done according to standard in four functional model including: non-performing turned on, sleep mode, performing office program and performing audio visual files.

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Result: Magnetic field values for all laptops were almost constant and about 28-32 mA/m. The results of measurements related to the electric field showed different values at distances of 30, 60 and 90 cm around the laptops on four sides. Moreover, mean electric field on the keyboard at the four operating modes were statistically different for DELL and hp laptops (P< 0/05).

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Conclusion: The results of this study showed that laptops produce extremely low frequency (ELF) electric and magnetic fields which their intensity depends on laptop type, laptop operation mode and the location of the measurement.

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Introduction: Job design approach is one of the significant concepts in ergonomics Experts believe that integration of macro ergonomics and job design can lead to improved productivity in the organizations. Therefore, this study examined the relationships between job design, performance and job satisfaction.

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Methods and Materials: This cross - sectional study was done in 11 branches of one of the bank in Hamadan. Job Design Questionnaire, Job Satisfaction Questionnaires and Bank Performance Indicator were used in order to collect data. spearman correlation coefficient was used for determining the correlation between each two variables.

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Results: This study showed that the motivational approach was the minimum approach (3.8%), and the mechanical approach, was the dominant approach (74.7%) in the study branches and the majority of branches had an average level of job satisfaction. Moreover, there was a significant positive correlation between job design (motivational and cognitive approaches) and job satisfaction. In addition, the results showed that between job design (Motivational approach) and satisfaction were significantly correlated with performance, (p = 0.05).

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Conclusion: Regarding the role of job design in job satisfaction and employees, performance, it can be stated that job redesign towards a motivational approach and considering the principles of ergonomics in the workplace, can play an important role in efficiency and productivity of an organization.

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Introduction: The Power plants are as the major industries that have a large number of workers, providing they health is important. Exposure to occupational noise is the pervasive physical agent in industries like power plants and may impact health and for safety status for people. Determination of the sources of noise in workplaces is important step in noise control plans. This study aimed to assess noise pollution and determine the main sources of noise in a power plant for.

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Material and Method: This descriptive cross-sectional study was conducted on the ground floor of the turbine unit of a thermal power plant. Measurements was done based on the ISO-9612 and ISO-11200 standard using by the calibrated sound level meter model TES-1389 on “A” frequency weighting and “Slow” mode for time response. Surfer V.10 software was used for interpolation and noise maps producing. Based on grid method measuring for indicating of noise propagation, we set buffer of danger areas to determine main sources of noise. Also, we used the minimized grid method for measuring and study of noise denotation in vertical surface in each main sources.

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Result: The results showed that the measured indoor sound pressure level in all areas where at the risk category of the units. The highest average sound pressure level was belonged to the unit 2, with 93.1 dB(A). We find the feed water pumps were the main sources in all of the studied units. Among the four main components of the main sources, the highest noise levels associated with the main pump and the gearbox section with about 100 9B(L) and dominant frequency of 2000 Hz.

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Conclusion: Considering that feed water pumps had major sources in indoor power plant noise pollution, engineering noise control such as providing enclosures is necessary to reduce noise pollution to safe levels in the studied plant it is necessary.

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Introduction: Children have been known to spend most of their time at school. They learn their sitting habits in this period of time. Incorrect sitting postures and inappropriate school furniture can result in abnormalities in the vertebral column, back pain, neck pain, Fatigue and discomfort. Hence, this study was aimed to examine the match between students’ body dimensions and existing benches and desks dimensions in Hamadan female primary schools.

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Material and Method: In this study, 624 students of Hamadan female primary schools were investigated and some of their anthropometric dimensions including shoulder height, elbow height, knee height, popliteal height, popliteal-buttock length and hip breadth were measured. In this sense, a chair (with adjustable height, depth and elbow support) and a caliper with movable jaw were used for measurement of anthropometric dimensions. The measurements were performed in a way that thighs were in full contact with the seat, there was a right angle between the thighs and legs, the feet were in full contact with the movable pedal, the trunk was straight and the back and hips were in full contact with the backrest. Following, the match of the dimensions of existing benches and desks with the appropriate dimensions (based on the students’ anthropometric dimensions) were examined.

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Result: The results showed that the seat height, seat depth, seat width, back rest height, desk height, underneath desk height were in acceptable rangefor 10.1%, 17.3%, 5.6%, 53.5%, 1.9% and 31.1% of students, respectively.

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Conclusion: Despite differences in the body dimensions of primary school students, there is no regularity in using of school furniture. Overall, the dimensions of existing benches and desks are not matched with the anthropometric dimensions of students.

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Introduction: The bank employees usually require the use of computers for long duration in a static position to get the work done. The present study aimed to evaluate the risk factors for musculoskeletal disorder using the ROSA method among the employees of Sepah Bank. An ergonomic intervention was also performed in order to improve the working conditions.

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Material and Methods: This interventional descriptive-analytical study was carried out among 165 office employees of central building of Sepah Bank. Using random sampling, the subjects were initially divided into two groups of case and control. Before and after the intervention, ROSA method and Nordic questionnaire was respectively used to evaluate the risk factors that cause musculoskeletal disorders and the prevalence of musculoskeletal disorders. The data were collected two weeks prior the interventions and 9 months after the interventions. SPSS software version 16 was utilized for data analysis and the effectiveness of intervention was determined.

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Results: Before the intervention, the mean ROSA scores of all groups' workstations were above 5 with high risk. The results obtained 9 months after the interventions manifested a statistically significant decrease (P<0.001) in the ROSA mean scores and its components in the groups who received the interventions. 9 months after the intervention, the prevalence of musculoskeletal disorders among the subjects who had received intervention showed a significant reduction, as well (0.001> p).

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Conclusion: Using the ROSA technique was seemed to be beneficialto assess the ergonomic risk factors of office works, and the deficiencies in the workstation can be identified through this method. Moreover,by design and implementation of an educational intervention program along with engineering interventions which comply with the elements of this technique, the defects can be eliminated.

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Introduction: Studies have shown that bank clerks experience high levels of stress. Stress is known as the main cause of reduction of job satisfaction and staff commitment and overall organization performance. This study aimed to investigate the association between psychosocial stressors, organizational structure, and job satisfaction.
 

Methods and Materials: This cross-sectional study was performed in 11 branches of a bank in Hamadan. In order to collect data, General Nordic Questionnaire (QPS Nordic 34+), Organizational Structure and Job Satisfaction Questionnaires were used. For determining the relationship between the two variables spearman correlation coefficient was used. Moreover, chi-square test was used to investigate the association between qualitative variables.
 

Results: Job stress (57%) and job satisfaction (39%) of the subjects were in the average level, and structure of the majority of the branches was somewhat inflexible (69%). What is more, there was a significant positive correlation between job stress and dimensions of organizational structure (centralization, formalization). Results manifested a significant correlation between organizational structure and job satisfaction (P-value= 0.05).
 

Conclusion: Considering the effect of organizational structure and work-related psychosocial stressors on job satisfaction, it can be stated that organizational restructuring to achieve organic structures and paying more attention to psychosocial stressors in the workplace, can play an effective role in the efficiency and productivity of the organization.

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Introduction: Recent evidence indicates that lighting can affect physiological and neurobehavioral human functions, referred to as non-image forming (NIF) effects of lighteffects. This study aimed to determine the effects of illumination levels and correlated color temperature (CCT) on alertness and performance under NIF conditions.
Material and Methods: In this study, 22 participants were exposed to light at various levels of illumination, including very low illuminance (<5 lux, control) and light conditions with correlated color temperatures (CCT) of 4000 K, 8000 K, and 12000 K at 300 and 500 lux. The data collection process included recording the power of brainwaves (alpha, alpha-theta, beta, and theta), sleepiness and mood scales, and cognitive performance tests for sustained attention, psychomotor vigilance task (PVT), working memory, and inhibitory capacity.
Results: The results indicated that 500 lux light conditions at correlated color temperatures of 8000 and 12000K significantly reduced normalized alpha, alpha-theta power, subjective sleepiness, and performance compared to the dim light condition. Under illumination levels of 300 and 500 lux, there were no significant differences in the measured values of the variables.
Conclusion: Lighting interventions can be used as a supplement to other strategies for increasing alertness and performance in the workplace.

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Introduction: Despite the numerous studies on occupational noise-induced hearing loss, there is limited documentation on the vibration effects on the workers’ auditory system. Heavy equipment drivers are exposed to high levels of whole-body vibration (WBV) and noise. Therefore, this study aims to investigate the heavy equipment drivers’ auditory response to WBV exposure and combined exposure to noise and WBV.
Material and Methods: 30 male heavy equipment drivers with an average age of 32.40 ± 4.91 years participated in this study, which was designed based on the repeated measurements model. During 3 defined scenarios of exposure to WBV, combined exposure to noise and WBV, as well as the scenario without exposure, the drivers’ auditory response was measured using distortion product otoacoustic emissions (DPOAE). Statistical analyses were performed by IBM SPSS-25 software.
Results: The range of heavy equipment in-cabin noise was 84-89 dB. Also, the most exposure of drivers to WBV was obtained in the Z axis with an average acceleration of 1.29 m/s2. The DPOAE amplitude of the drivers in all three investigated scenarios showed significant changes (P<0.05); But in comparison between different scenarios, exposure to WBV and combined exposure to noise and WBV had a significant effect on the response of the auditory system of the participants in the study compared to the scenario without exposure (P<0.05). Also, there was a significant difference in the changes of the DPOAE amplitude in different frequencies; Thus, the most changes in the DPOAE amplitude were observed in the frequencies of around 4000 Hz.
Conclusion: The results of this study showed the damaging consequences of exposure to noise and WBV on the auditory response; In addition, the present study provided evidence of synergistic effects of combined exposure to noise and WBV on heavy equipment drivers.