Effect of hypoxia on human cognitive ability and indoor oxygen environment demand for sojourners at high altitude

Abstract

The hypoxic environment on mountain plateaus exerts a significant negative impact on human cognitive ability and physiological well-being. Although progress has been made in the study of the cognitive decline of sojourners exposed to hypoxic environments, further knowledge that establishes the proper indoor oxygen environment beneficial for human cognitive ability is not available. In this study, a cognitive ability experiment was conducted on the Tibetan Plateau, China. Seventy-two subjects were selected based on the stay length (i.e., the length of their stay) and the original altitude (i.e., the altitude the people moved away from), and were exposed to three different indoor oxygen concentrations. The subjects’ physiological condition was monitored, and their cognitive abilities were assessed using a neurobehavioral assessment system. The results showed that the stay length and the original altitude affected their cognitive abilities. The memory ability of the sojourners changed most with changes in oxygen concentration. Suitable indoor oxygen concentrations were proposed based on human comprehensive oxygen demand. Concentrations were 26.22% and 23.40% for sojourners with stay lengths from less than a month up to approximately one year, respectively, when their original altitudes were below 500 m. Concentrations were 25.67% and 21.42% for those with stay lengths shorter than a month and up to approximately one year, respectively, when their original altitudes ranged between 500 and 3000 m. In this case, 26.22% and 25.67% were the calculated value of oxygen volume fractions, respectively. This study provides guidance for the design of indoor oxygen environments in plateau regions.