| Cognitive ability determines a person’s ability to receive and process information from the outside environment,which directly affects people’s daily learning and work efficiency.Since the cerebral cortex,which controls cognitive ability,is extremely sensitive to the oxygen environment around the human body,human cognitive ability will be greatly affected hypoxic environment at high altitude.At present,the design standard of indoor oxygen environment in plateau is mainly based on meeting physiological safety,with little consideration given to the cognitive ability of indoor personnel,and there are few studies on the indoor oxygen environment to meet the demand of cognitive ability of sojourners to Tibet.In addition,although some progress has been made in studies related to cognitive decline of travelers in high altitude environments,there is still a lack of indoor oxygen environment standards conducive to the protection of human cognitive ability.Due to the reasons of construction and aid for Tibet,business and travel scientific research,sojourners may live at high altitudes for several months to several years for a variety of reasons.Therefore,as places to live,work or study,their comprehensive needs for physiological safety and cognitive ability should be taken into account.This paper aims to meet the comprehensive needs of the sojourners in combination with physiological safety and cognitive ability,and explores the appropriate indoor oxygen environment design parameters at high altitude by comprehensively applying mechanism analysis,experimental testing and other methods.Firstly,based on neurologic theory and cognitive ability evaluation method,the cognitive ability evaluation method of sojourners at high altitude was established.Secondly,72 subjects were selected according to the entry length and the original altitude,and exposed to three different conditions of oxygen concentration.The physiological status of the subjects was monitored,and the cognitive ability assessment system was used to evaluate their sensory ability,thinking ability,memory ability and reaction ability.Then,from the dual dimensions of time and space,in which different entry length and original altitude analyzes sojourners,the change rule of the cognitive ability and hypoxia adaptation to master the high altitudes of oxygen on the Tibet people physiological indexes and the influence of cognitive ability.Based on the classification standard of indoor oxygen environment parameters under hypoxic condition at high altitude,a method of classification of indoor oxygen environment parameters based on cognitive ability was derived.Finally,considering the influence of indoor environment on physiological safety and cognitive ability,the appropriate indoor oxygen concentration for comprehensive oxygen demand of sojourners is proposed.Specific conclusions are as follows:(1)For all sojourners,with the increase of ambient oxygen concentration,which suggested that the changes in cognitive ability of the plateau population were not balanced,and the effects of hypoxia at the same level on different cognitive functions would be different.When the ambient oxygen concentration increased from 21.03% to24.95%,memory ability showed the largest increase,with a 37.2% increase,then reaction ability and thinking ability came down,increased by 35.7% and 32.5%respectively,and sensory ability increased by 24.8%,which was least.(2)For the sojourners,the higher environmental oxygen concentration might not be a better one.Through the study of the quantitative relationship between the physiological parameters and cognitive ability of the sojourners,we found that with the increase of oxygen concentration,the cognitive ability of the sojourners has a critical peak and then decrease.The physiological parameters of the sojourners were correlated with their cognitive ability,heart rate had the highest correlation,followed by heart rate variability,and blood oxygen saturation had the lowest correlation.Besides,heart rate and heart rate variability were significantly correlated with sensory ability,thinking ability,sensor ability,and reaction ability.The correlation coefficients of heart rate and perception ability,thinking ability,memory ability and reaction ability were 0.749,03558,0.714 and 0.802,respectively.The correlation coefficients of heart rate variability sensor ability,thinking ability,memory ability and reaction ability were-0.692,-0.527,-0.623 and-0.511,respectively.(3)With continuous oxygen supply for 1h one day,the change of cognitive ability of the sojourners was not balanced,and the influence of the same level of oxygen supply on different cognitive functions was also different.When 24.95% oxygen was supplied continuously for 3 days,the cognitive abilities of sensor,thinking,memory and reaction increased by 6.5%,13.3%,15.8% and 9.9%,respectively.When 22.96% of the oxygen was supplied for 3 days,the cognitive abilities of sensor,thinking,memory and reaction increased by 13.7%,16.2%,34.4% and 29.4%,respectively.In the 3 days continuous oxygen supply,the cognitive ability of the population in the high-oxygen-enrichment condition was higher than that in the low-oxygen-enrichment condition.Blood oxygen saturation and heart rate had fluctuation change in the 3 days of oxygen enrichment,which indicated that while diffuse oxygen supply effectively alleviated the symptoms of plateau,the body was still engaged in hypoxia compensation and plateau acclimatization,which was conducive to the emergency plateau personnel to gradually adapt to the altitude hypoxia environment on the premise of ensuring safety.(4)Suitable indoor oxygen concentrations were proposed based on human cognitive ability,which were 26.32% and 23.14% for those with stay lengths of less than a month and approximately one year when their original altitudes were less than500 m,and were 25.58% and 21.46% for those with stay lengths of less than a month and approximately one year when their original altitudes were between 500 and 3000 m. |
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