Effects of Shift Work on Cognitive Performance, Sleep Quality, and Sleepiness among Petrochemical Control Room Operators.

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. Sixty shift workers participated in this study. Cognitive performance was evaluated using a number of objective tests, including continuous performance test, n-back test, and simple reaction time test; sleepiness was measured using the subjective Karolinska Sleepiness Scale (KSS); and sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) questionnaire. ANCOVA, t-test, and repeated-measures ANOVA were applied for statistical analyses, and the significance level was set at p < 0.05. All variables related to cognitive performance, except for omission error, significantly decreased at the end of both day and night shifts (p < 0.0001). There were also significant differences between the day and night shifts in terms of the variables of omission error (p < 0.027) and commission error (p < 0.036). A significant difference was also observed between daily and nightly trends of sleepiness (p < 0.0001) 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 < 0.01). 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.

The effects of consecutive night shifts and shift length on cognitive performance and sleepiness: a field study.

INTRODUCTION: The aim of this study was to evaluate the effects of consecutive night shifts (CNS) and shift length on cognitive performance and sleepiness. MATERIALS AND METHODS: This study evaluated the sleepiness and performance of 30 control room operators (CROs) working in 7 nights, 7 days, 7 days off (7N7D7O) and 30 CROs working in 4 nights, 7 days, 3 nights, 7 days off (4N7D3N7O) shift patterns in a petrochemical complex on the last night shift before swinging into the day shift. To assess cognitive performance, the n-back test, continuous performance test and simple reaction time test were employed. To assess sleepiness, the Karolinska sleepiness scale was used. RESULTS: Both schedules indicated that the correct responses and response times of working memory were reduced (p = 0.001), while intentional errors and sleepiness increased during the shift work (p = 0.001). CNS had a significant impact on reaction time and commission errors (p = 0.001). CONCLUSION: The main duty of 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 CNS in a rotating shift system is a contribution to improving CRO performance and enhancing safety.

Evaluation of Coordination of Emergency Response Team through the Social Network Analysis. Case Study: Oil and Gas Refinery.

BACKGROUND: The purpose of this study was to examine the cohesions status of the coordination within response teams in the emergency response team (ERT) in a refinery. METHODS: For this study, cohesion indicators of social network analysis (SNA; density, degree centrality, reciprocity, and transitivity) were utilized to examine the coordination of the response teams as a whole network. The ERT of this research, which was a case study, included seven teams consisting of 152 members. The required data were collected through structured interviews and were analyzed using the UCINET 6.0 Social Network Analysis Program. RESULTS: The results reported a relatively low number of triple connections, poor coordination with key members, and a high level of mutual relations in the network with low density, all implying that there were low cohesions of coordination in the ERT. CONCLUSION: The results showed that SNA provided a quantitative and logical approach for the examination of the coordination status among response teams and it also provided a main opportunity for managers and planners to have a clear understanding of the presented status. The research concluded that fundamental efforts were needed to improve the presented situations.

Study on the performance of wet electroscrubber in purifying airborne particles.

BACKGROUND: In this study, an electroscrubber was designed and experimented for evaluation of integrating particle and droplet charging effects separately and jointly on collection efficiency of a spray tower and also to discover the optimal condition. METHODS: A homogenous concentration of relatively fine particles was introduced to influent air stream and electroscrubber efficiency in purifying them was determined through the measurement of input and output particles concentration. The effect of various conditions such as particles and droplets charging alone and together (bipolar) for several applied voltages has been studied. RESULTS: In all of experiments, the applied charging voltage has a key role in promotion of electroscrubber efficiency. Maximum collection efficiency has achieved for 15 Kilovolt (Kv). The effectiveness of bipolar charging of particles and droplets with 15 Kv was higher than that of no-charging and singly charging. In other words, efficiency can be increased from 84.43% to 93.22 for total particles and from 50.8% to 75.16% for submicron particles. The maximum improvement of collection efficiency (42.2%) relates to bipolar charging of the initial size group with diameter smaller than 0.3 micrometer (µm) and the minimum (0.5%) to sizing group of 11 with diameter 4-5 µm. CONCLUSIONS: This approach can be an appropriate option for the purpose of purifying submicron particles in spray tower scrubbers.