Associations of Human Cognitive Abilities with Elevated Carbon Dioxide Concentrations in an Enclosed Chamber

Abstract

Fifteen participants were exposed in an enclosed environmental chamber to investigate the effects of elevated carbon dioxide (CO2) concentration on their cognitive abilities. Three CO2 conditions (1500, 3500, and 5000 ppm) were achieved by constant air supply and additional ultrapure CO2. All participants received the same exposure under each condition, during which they performed six cognitive tests evaluating human perception, attention, short-term working memory, risky decision-making, and executive ability. Generalized additive mixed effects model (GAMM) results showed no statistically significant differences in performance on the reaction time (RT) tests, the speed perception test, and the 2-back test. This suggests that elevated CO2 concentrations below 5000 ppm did not affect participants’ perception and short-term working memory. However, a significant increase in response time was observed in the visual search (VS) test, the balloon simulation risk test (BART), and the Stroop test at 5000 ppm compared to lower exposure concentrations. The slower responses reflected the detrimental effects of elevated CO2 concentrations on visual attention, risky decision-making, and executive ability. The findings suggest that the control level of CO2 concentrations should be tighter in enclosed workplaces where rapid response and operational safety are required.

Experimental Evaluation of Noise Exposure Effects on Subjective Perceptions and Cognitive Performance

“…Generalized additive mixed effect model (GAMM) analyses [47,48,55,56] and the correlation analyses were performed using the open-source statistical package R version 3.6.1 (R Project for Statistical Computing, Vienna, Austria) to test the relationships between noise exposures and performance metrics, treating the subject as a random effect. In addition, the PLS-SEM method was used with the SmartPLS 3.0 software (SmartPLS GmbH, Bönningstedt, Germany) to explore the underlying mechanism of noise effects.…”

“…Seven computer-based cognitive tests, summarized in Table 2, were adopted based on the information-processing of the human mind [48]. The details are described as follows.…”

Effects of elevated carbon dioxide levels on response speed in cognitive test

“…Response speed was widely used in previous studies as one of the key parameters to measure people's cognitive performance. Among the studies which found significant effects of CO2 on cognitive performance, some did not find significant effects of exposures to elevated CO2 levels on response speed [17], [18], some studies found that response speed significantly increased in some cognitive tasks under higher concentrations [20], and some showed decreased response speed under higher CO2 levels [6]- [8], [13], [21].…”