Effects of carbon dioxide exposure on human cognitive abilities in an enclosed workplace environment

In this study, 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 ppm, 3500 ppm, and 5000 ppm) were achieved by constant air supply and additional ultra-pure 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. During each exposure condition, the reaction time (RT) test, speed perception test, visual search (VS), 2-back test, balloon analogue risk test (BART), and Stroop test were successively conducted with rest intervals of approximately 13min. The results showed that there was no statistically-significant difference in the performance of RT tests, speed perception test, and 2-back test. This indicated that the elevated CO₂ concentration below 5000 ppm did not affect the participants' perception and short-term working memory. However, significant increase of response time was observed in the VS test, BART, and Stroop test at 5000 ppm compared with lower exposure concentrations. The slower reaction reflected the negative effects of elevated CO₂ concentration on human visual attention, risky decision making, and executive ability. The findings suggest that work performance could be negatively affected by the exposure to CO₂ at the current occupational concentration limit.