Iranian Journal of Ergonomics

Using the Need for Recovery Scale to Assess Workload in Mine Workers and Its Relationship With Demographics

Reza Kalantari

Introduction: Work-related fatigue is a source of concern, even in most industrialized countries. One of the most important factors influencing an employee’s physical and mental condition is the degree to which employees are able to recover from fatigue and stress after work. Factors such as workload can cause fatigue in workers. The aim of this study was using the need for recovery scale to assess workload in mine workers and its relationship with demographics.

Methods: In this cross-sectional study, 80 workers of a mine were surveyed. The data gathering tools used in this study were demographic characteristics questionnaire and the need for recovery scale. The scale assesses the workers workload with 11 two-optioned phrases. Mean, standard deviation, and Pearson’s correlation coefficient and ANOVA tests were used in order for data analysis.

Results: Mean (SD) score of the need for recovery scale was 55.22 (23.93), indicating moderately high workload in the workers. A total of 58.7% of workers experienced high levels of workload. Among the demographics, only body weight had a significant relationship with the need for recovery score (P value = 0.043).

Conclusions: Due to the relatively high need for recovery in the study population, solutions should be employed, such as reducing the workload, use of work-rest schedules, performing heavy tasks within teams, and providing conditions for proper and enough recovery after work, which can increase health conditions of workers.

The Study of Sleep Health Education Effect on Sleep Quality Among Lorestan Nursing Personnel

Babak Moeini

Introduction: In some occupations such as nursing, due to specific job circumstances, sleep quality is poor. Given the importance of sleep quality, this study examined the impact of sleep health education on sleep quality among nurses.

Methods: This was an interventional and quasi-experimental research. The study population included the nursing personnel serving at elected Lorestan university hospitals. Among them, 50 were randomly assigned to a control group and 50 were selected as the intervention group. Data collection was organized according to a questionnaire posing demographical questions as well as Pittsburgh Sleep Quality questionnaire. Training intervention for the intervention group was carried out. Consequently passing 45 days, both control and intervention groups were called out for questionnaire filling. Data analysis was conducted using SPSS software, independent t-test and McNemar’s test.

Results: The study results showed that after the intervention training, there was a significant difference in terms of the average sleep score among the personnel of nursing, and after the training intervention, the sleep status of the personnel got improved compared to those of the control group (P ≤ 0.05).

Conclusions: The study results showed that sleep quality-improving skills trainings had an important and decisive impact on the sleep quality of nursing personnel and holding educational courses in this field for personnel can be useful.

Investigation of Correlation of Musculoskeletal Disorders With Work Ability Index and Allowable Load Lifting Limit

Sakineh Varmazyar

Introduction: Heavy load lifting or occupational and individual factors are effective hazard agents in the occurrence of musculoskeletal disorders. Therefore, the aim of the present study was investigating the correlation of musculoskeletal disorders with work ability index and allowable load lifting limit.

Methods: This analytical and cross-sectional study was conducted using census (n = 60) among the kitchen workers in Qazvin teaching hospitals in 2016. Data were collected through questionnaires including pain prevalence, work ability index and allowable load lifting limit. Data was analyzed by single and multiple regression logistic using SPSS 16 software.

Results: The highest prevalence was observed in the lower back (78.3%). Of the workers, 61.7% reported a good level of work ability index and 58.3% of the workplaces were in unsafe conditions of load handling. Unsafe condition alone increased the prevalence of shoulder and neck pain about 7 times and the lower back pain 4 times, and in interaction with other risk factors, the prevalence of neck and shoulder pains had 25 and 28 times increase, respectively. Also, subjects with good levels of ability compared to subjects with excellent levels of ability were 9 times more in exposure of musculoskeletal disorders.

Conclusions: Risk factors such as body mass index, work ability and allowable load lifting limit can affect the prevalence of musculoskeletal disorders. So, selection of subjects with good and excellent work ability levels and compliance with the load limit are the effective solutions in increasing the productivity and reducing musculoskeletal disorders among kitchen workers.

Creating a Numerical Index for Measurement of Workload Levels in the Simulator of Piloting Tasks

Kamran Raissi

Introduction: Pilot performance investigation during multi-tasking operations requires a procedure, in which the parameters related to the desired scenario of the simulator are obtained in a systematic manner. The multi-attribute task battery (MATB-II) is a standard simulator of generic piloting tasks developed by national aeronautics and space administration (NASA).

Methods: Employing information theory concepts, baud rate generated in all subsystems of the MATB-II were calculated and then, a unique numerical index presenting an estimation of overall workload was extracted. In the next step, three tests with different levels of workload were conducted to examine the validity of the offered criteria. These tests were performed by a group of subjects on the role of human pilots, while recording their own experiences about perceived workload via NASA-TLX.

Results: The results confirmed that there were significant differences between averages of scores assigned by subjects to the total workload, for three levels of difficulty defined based on information theory (P-value < 0.001). This variable shows considerable growth from low to medium and from medium to high categories of workload level.

Conclusions: The proposed quantitative index is effective enough for determination of workload levels in the MATB-II simulator.

The Effects of Divided Attention and Cognitive Distraction on Driver’s Performance Among People Aged over 65

Mahdi Ebnali Heidari

Introduction: Driving is a complex task engaging high level of cognitive and motor processes. Adding to this complexity, engagement in cognitive secondary tasks such as talking with other passengers, speaking on the cell phone or listening to radio may effect driving performance. In addition, age-related cognitive limitations may adversely challenge driving performance. As the number of elderly drivers is rising, it is important to pay more attention to this matter.

Methods: The effects of cognitive secondary tasks on driving performance were explored through two on-road experiments (with and without listening to a recorded dialogue). In this study thirty-two individuals (male, M = 72.6, SD = 5.43) voluntarily took part in the experiments. The mean driving speed, duration of driving in unsafe-zones, numbers of overtaking, and deviation of lateral lane position were recorded, adopting a radar system and video camera. After determination of the normality of data, paired t test and correlation analysis were conducted.

Results: Mean driving speed (P < 0.05), duration of driving in an unsafe zone (P < 0.05), and numbers of overtaking (P < 0.001) showed considerable reduction of participants’ engagement in listening to the recorded dialogue. In contrast, mean deviation of lateral lane position increased.

Conclusions: The findings revealed that driving performance of elderly drivers was effected when listening to a recorded dialogue. However, in order to increase driving safety, they adopted some compensating strategies.

Examining the Role of Fatigue and Cognitive Failures in Predicting Work Situation Awareness Among Employees of Pars Khodro Company

Fariba Kiani

Introduction: Studies have shown that one of the factors affecting occupational injuries is employees’ awareness of work situation. Therefore, it is important to identify factors affecting situational awareness. The aim of this study was to investigate the role of fatigue and cognitive failures in predicting work situation awareness among employees.

Methods: This study was a cross-sectional study with a descriptive-correlational design. The sample consisted of 154 employees of the Tehran Pars Khodro Company in 2015, who was selected by stratified random sampling method and responded to questionnaires of fatigue from Chalder et al. (1993), cognitive failures from Broadbent et al. (1982) and work situation awareness of Sneddon et al. (2006). Data were analyzed using Pearson correlation coefficient and stepwise regression analysis.

Results: The results showed that there were significant relationships between fatigue, cognitive failures and work situation awareness (P < 0.01). Also, fatigue and cognitive failures predicted almost 14% and 25% of the variance of work situation awareness among employees, respectively (P < 0.05).

Conclusions: The reduction of employees’ cognitive and emotional capacity could reduce their awareness of work situation.

Evaluation of Effects of Different Levels of Brightness on Attention and Reaction Time under Laboratory Conditions

Zohre Mohebian

Introduction: Few studies were conducted to determine the effects of lighting on cognitive performance. However, they could not reach a decisive conclusion. This study investigated cognitive performance of university students exposed to different levels of lighting under laboratory conditions.

Methods: In this experimental study, 33 subjects (age range 19-26 years) performed cognitive tests. Participants were exposed to three levels of lighting (200, 500 and 1500lux) in laboratory conditions while performing CPT tests to investigate percentage of attention and reaction time machine that measures reaction time.

Results: The results of this study showed that the maximum percentage of attention (99.75%) belonged to lighting of 1500 (lux) and the minimum percentage of attention was related to 500(lux) (99.36%). statistical analysis showed significant differences in percentage of attention in different levels of lighting (P=0.004). In addition, results of data analysis showed that increase in intensity of lighting can make a significant change in the average response time (P˂0.001), correct response (P=0.004), commission error (P=0.001) and omission error (P=0.017). With increasing the lighting intensity, reaction time has decreased. The reaction time showed significant differences at all levels of lighting (P˂0.001)

Conclusion: According to the findings of this study, lighting causes a decrease in reaction time and increase in attention. Thus, the lighting should be taken into account while designing of job and tasks which need attention or reaction time.

The effects of ergonomic interventions in manual activities to reduce musculoskeletal disorders in manual activities by ManTRA

Abdollah Vahedi

Abstract:

Introduction: Work-related musculoskeletal disorders (WMSDs) occur when the pressure that applied to musculoskeletal tissue is/be more than tissue tolerant capabilities. This study aimed to assess the risk factors cause musculoskeletal disorders associated with manual tasks using ManTRA and conducted ergonomics intervention program(educational- engineering) among workers in the printing industry.

MethodS: In this interventional case-control study, 40 workers who performed manual tasks, ( 20 case group and 20 control group) were chosen and were investigated. Nordic Body Map was used to determine the intensity and position of pain in the Different part of the body. ManTRA method was performed to evaluate cumulative scores in four regions of the body (wrist / hand / arm - shoulder / neck - back - lower limb) for each workers before and after the intervention. Data analysis was done using SPSS.

Results: Data analysis showed that mean intensity of pain in the control group before and after intervention in the various regions of the body such as head /neck (p=0.012), right shoulder/arm (p=0.012), left shoulder/arm(p=0.043), back (p=0.003), right hand / wrist (p=0.028), left hand / wrist (p=0.027), right knee/ hip (p=0.005), left knee/ hip (p=0.005), right leg (p=0.012) & left leg(p=0.028) were significant.Cumulative score was also significant in the body regions such as arm/wrist /hand (p=0.001) and shoulder /neck (p=0.001) before and after the interventional program.

Conclusion: On the basis of the findings of this study, it could be noted that the ergonomic interventional program was effective to reduce the intensity of pain in the various regions of the body and risk factors causing cumulative damage in the workplace.