INTRODUCTION: The effects of low-grade hypoxia on cognitive function are reported in this paper. The study compared cognitive function during short exposures at four different altitudes.METHODS: Ninety-one subjects were exposed to simulated altitudes of ground level, 1524, 2438, and 3658 m (5000, 8000, and 12,000 ft) in the Brooks City-Base altitude pressure chamber in a balanced design. Oxygen saturation, heart rate, and cognitive performance on seven different cognitive tasks were measured. In addition, subjects indicated their symptoms from a 33-item subjective symptom survey.RESULTS: As designed, oxygen saturation decreased and heart rate increased with higher altitudes. Very small degradations in performance were found at the two highest altitudes for only two of the cognitive tasks (continuous performance and grammatical reasoning). In the subjective symptom survey, 18 of the 33 possible symptoms were more common at 3658 m (12,000 ft) than at ground level.CONCLUSIONS: The findings indicated a minimal influence of low-grade hypoxia on cognitive performance in contrast to some existing classic symptoms of hypoxia.Pilmanis AA, Balldin UI, Fischer JR. Cognition effects of low-grade hypoxia. Aerosp Med Hum Perform. 2016; 87(7):596–603.