Human responses to carbon dioxide, a follow-up study at recommended exposure limits in non-industrial environments

Window and door opening behavior, carbon dioxide concentration, temperature, and energy use during the heating season in classrooms with different ventilation retrofits—ASHRAE RP1624

“…The measured CO 2 concentrations were below the 8-hour maximum permissible occupational exposure level of 5000 ppm (OSHA 2017). Also, there is no conclusive evidence that CO 2 itself among adults should increase the risk of discomfort or health problems or the cognitive performance of simple tasks (Liu et al 2017;Zhang et al 2016Zhang et al , 2017, although demanding cognitive tasks have been shown to be affected (Allen et al 2016;Satish et al 2012). CO 2 at the concentrations measured in the current study should thus not be considered a toxic compound.…”

Using EEG to characterise drowsiness during short duration exposure to elevated indoor Carbon Dioxide concentrations

“…Statistical power analysis was calculated a-priori using G*Power software [37]. Effect size was estimated at 0.4 based on similar experiments [12], number of groups = 2 (treatment, control), number of measurements = 3 (Baseline, High-CO 2 , Post ventilation- defined below), significance level 0.05. This gave a between factors recommendation for 58 participants, and recommendations for both within-factors and within-between factors of 18 participants.…”

“…A large body of literature exists relating poor ventilation to mild health symptoms [2,5-7] and lowered cognitive performance [4,8-10]. Office-realistic levels of CO 2 are reported to be typically < 3,000 ppm, but whether CO 2 itself negatively impacts cognitive performance, or whether other pollutants such as volatile organic compounds (VOCs), including human bio-effluents, are responsible, is still unclear [11,12]. Human performance effects have been recorded in studies both where CO 2 is accompanied by human bio-effluents (e.g.…”

“…Human performance effects have been recorded in studies both where CO 2 is accompanied by human bio-effluents (e.g. the CO 2 concentration is a product of poor ventilation in occupied spaces) [4,13,14] and where pure CO 2 gas is added to a room to achieve steady-state concentrations [12,13,15–18].…”

“…Resting EEG and other physiological and subjective parameters were recorded from participants exposed to 2,700 ± 300 ppm of CO 2 in an office for 10 minutes, as a means of determining the physiological changes of a short-duration exposure to elevated CO 2 concentration and testing for EEG data indicative of a progression towards drowsiness. A key aim of the paper is to explore the effect of CO 2 on drowsiness, given that drowsiness is a determinant of human work performance [20,35] and compare results to both cognitive science literature on the cognitive performance effects of office-realistic concentrations of CO 2 [4,8,10,12,15,16] and neurophysiology literature on the neurological effects of much higher concentrations of CO 2 [30–33].…”