The effects of carbon dioxide exposure concentrations on human vigilance and sentiment in an enclosed workplace environment

In this study, fifteen participants were exposed to different carbon dioxide (CO₂) concentrations in an enclosed environmental chamber to investigate the potential effects of elevated CO₂ concentrations on human vigilance and sentiment. The psychomotor vigilance test (PVT), the Karolinska Sleepiness Scale (KSS), and the Positive and Negative Affect Schedule (PANAS) were measured before and after each 4-hour CO₂ exposure session. The statistical analyses of the PVT performance metrics showed that the human vigilance decreased significantly with the elevated CO₂ concentration from 1500 ppm to above 3500 ppm, but no significant change was observed in the KSS score. Moreover, although the participants reported less positive and more negative emotions as the CO₂ exposure concentration increased, the effect of CO₂ concentration on human sentiment was not potent. In sum, the findings suggested a detrimental effect of CO₂ exposure concentration on human vigilance at the CO₂ concentration of 3500 ppm, which is below the current occupational exposure limit of 5000 ppm. It is worth noting that the order of CO₂ exposures was not balanced among the participants, which remains a major limitation of this study.