title: Assessment of operators' mental workload using physiological and subjective measures in cement, city traffic and power plant control centers.
abstract: BACKGROUND
  The present study aimed to evaluate the operators' mental workload (MW) of cement, city traffic control and power plant control centers using subjective and objective measures during system vital parameters monitoring.
  
  
  METHODS
  This cross-sectional study was conducted from June 2014 to February 2015 at the cement, city traffic control and power plant control centers. Electrocardiography and electroencephalography data were recorded from forty males during performing their daily working in resting, low mental workload (LMW), high mental workload (HMW) and recovery conditions (each block 5 minutes). The NASA-Task Load Index (TLX) was used to evaluate the subjective workload of the operators.
  
  
  RESULTS
  The results showed that increasing MW had a significant effect on the operators subjective responses in two conditions ([1,53] = 216.303, P < 0.001, η2 = 0.803). Also,the Task-MW interaction effect on operators subjective responses was significant (F [3, 53] = 12.628,P < 0.001, η2 = 0.417). Analysis of repeated measures analysis of variance (ANOVA) indicated that increasing mental demands had a significant effect on heart rate, low frequency/high frequency ratio, theta and alpha band activity.
  
  
  CONCLUSIONS
  The results suggested that when operators' mental demands especially in traffic control and power plant tasks increased, their mental fatigue and stress level increased and their mental health deteriorated. Therefore, it may be necessary to implement an ergonomic program or administrative control to manage mental probably health in these control centers. Furthermore, by evaluating MW, the control center director can organize the human resources for each MW condition to sustain the appropriate performance as well as improve system functions.
authors.affiliation: Department of Occupational Hygiene, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Fallahi
authors.affiliation: Department of Ergonomics, Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Motamedzade
authors.affiliation: Department of Ergonomics, Medical Sciences Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Rashid
authors.initials: R
authors.lastname: Heidarimoghadam
authors.affiliation: Modeling of Noncommunicable Diseases Research Center, Department of Biostatistics and Epidemiology, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Ali Reza
authors.initials: AR
authors.lastname: Soltanian
authors.affiliation: School of Health Sciences, University of Occupational & Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishiku, Kitakyushu 807-8555, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Miyake
keywords: ECG; EEG; Mental workload; NASA-TLX