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

¹ UCL Institute for Environmental Design and Engineering, The Bartlett, University College London, London, United Kingdom
² UCL GOS Institute of Child Health, Faculty of Population Health Sciences, University College London, London, United Kingdom

Abstract

To explore the associations of exposure to carbon dioxide with adults’ response speed, 69 participants were invited to participate in the experiment conducted in an environmentally controlled chamber. Participants were exposed alone in three separate sessions, each lasting one hour, with a fixed ventilation rate, temperature and relative humidity level and the CO2 levels fixed at 600ppm, 1500ppm and 2100ppm, respectively. A validated neurobehavioral test battery, the Behavioural Assessment and Research System (BARS) was used to assess participants’ cognitive performance, and response times were collected. Response speed was assessed in ten different tests. After adjusting for potential confounders (age, gender, and education), results showed no significant differences in eight out of the ten neurobehavioral tests. For the Selective Attention test, participants responded faster (lower response time) under CO₂ levels of 2100ppm compared to 600ppm (adj.β-coef. -17.57, 95% CI (-29.45, -5.68), p-value=0.004). For the Progressive Ratio Test, participants’ response times significantly decreased with CO₂ levels increased. Results indicate no statistical link between CO₂ levels and response speed, with only two out of ten comparisons being significant.