The effect of increasing the illumination on operators' visual performance in the control-room of a combined cycle power plant

BACKGROUND: Lighting is one of the environmental factors affecting the performance of the control room operators. Therefore, the aim of this study was to compare the control room operators’ visual performance in two different illumination conditions at a combined cycle power plant through field-work. METHODS: Sixteen operators in day shift were evaluated with the Freiburg Visual Acuity test (FrACT) software at two lighting systems with different intensities. It includes the first phase with fluorescent illumination system (Power: 40 W, Color Temperature: 4000 Kelvin, Luminous Flux: 2780 Lumen and Model: Pars Shahab) and the second phase with a combined illumination system includes fluorescent and LED (Power: 48 W, Color Temperature: 4000 Kelvin, Luminous Flux: 5400 Lumen and Model: Mazinoor). RESULTS: Based on the results, visual performance index and visual acuity significantly increased after the intervention (p < 0.001). As to contrast, more lighting significantly reduced the percentage of recognized contrast (p < 0.001) and increased the contrast performance index (p < 0.001). CONCLUSIONS: The results of this study showed that increasing the intensity of light from the values below the allowable limit to the values above the allowable limit would increase the visual indicators in individuals.

Heat stress and physical capacity: a case study of semi-professional footballers

The aim of this study was to determine heat stress effect on physical capacity of semi-professional footballers in Iran by means of oxygen consumption measurement, heart rate monitoring and WBGT assessment environmental conditions. This study compared two different thermal environmental conditions related to sub-maximal exercise and its effect on human physical capacity. Thirty two male footballers [age 25.9 +/- 1.4 year; height 176 +/- 2.9 cm and weight 71 +/- 9.8 kg] were investigated under four workloads [50,100,150 and 200 W] in two different thermal conditions in the morning [WBGT=21°C] and afternoon [WBGT=33°C] in summer. Each test cycle lasted for 10 minutes with a 10 min interval for recovery and rest between every workload. In the end of each stage, the heart rate, blood pressure, skin temperature and oral temperature were measured and recorded. Expired air was collected and its volume was measured using standard Douglas bags. The WBGT index was also used to monitor the stressful heat condition. Heart rate and VO[2] consumption findings for different workload showed a significant difference between morning and afternoon [P<0.001]. HR and VO[2] consumption in both morning and afternoon courses showed a liner relation [r=0.88, r=0.9 respectively]. With increasing work load beside heat stress, heart rate and oxygen consumption increased. It is recommended that with Ta>35°C or WBGT>28°C, physical activates and performing exercises should be avoided in order to reduce the risk of heat stress-related conditions in athletes