Present paper describes physiological responses as a result of exposures to CO2 (between 500 ppm to 3,000 ppm) with and without bioeffluents. Twenty-five subjects participated. They were exposed in the climate chamber for 255 minutes in groups of five at a time. During exposure, they performed different cognitive tasks and assessed their comfort and acute health symptoms. Besides, the following were determined: heart rate, blood pressure, oxygen saturation of blood, respiration rate, minute ventilation rate, nasal peak flow, forced expiratory volume, and the end-tidal CO2 pressure (ETCO2). Saliva samples were collected to analyze stress biomarkers. During exposure to CO2 with and without bioeffluents at 3,000 ppm, ETCO2 and minute ventilation rate were higher, while nasal peak flow decreased. These exposures caused also the increased heart rate during typing sessions. During exposures to CO2 with bioeffluents, the performance of Tsai-Partington test was reduced, and diastolic blood pressure and alpha-amylase increased after exposure compared with their levels before exposure, which may suggest higher arousal/stress. During exposure to CO2 without bioeffluents, the performance of Tsai-Partington test also was lower, which may suggest higher stress/arousal, too. However, no effects on blood pressure and alpha-amylase were seen for this exposure.