Effect of carbon dioxide concentration on respiratory parameters of occupants

Climate models imply that by 2100 atmospheric CO2 levels could exceed 900 ppm. At these levels, subscribing to current ventilation rates would lead to indoor CO2 levels ≥1,400 ppm, possibly impacting our physiology and other responses. We ran a randomized, within-subject study with 15 participants to examine the physiological effects of 2,5 hour exposure to three CO2 levels: 900 ppm, 1450 ppm (reduced ventilation), and 1450 ppm (pure CO2 added, ventilation same as 900 ppm). End-tidal CO2 and respiration rate across the different exposures were not significantly different. Spirometry parameters reduced significantly from the beginning to the end at reduced ventilation exposure compared to the 900 ppm condition (p<0.013), but not during exposure to pure CO2. The results suggest no effect of increased pure CO2 on some physiological parameters in contrary to reduced ventilation.