Surprising Effects of CO2 Exposure on Decision Making

Abstract

Carbon dioxide (CO 2 ) is released from humans while they live and work in spacecraft or spacesuits. Removal of this anthropogenic pollutant requires major resources, which increase dramatically as the permissible levels of CO 2 set to protect human health and performance are reduced. The current Spacecraft Maximum Allowable Concentration (SMAC) of CO 2 aboard the ISS is 5.3 mmHg; however, according to Chits (mission action requests), NASA and its international partners have agreed to control CO 2 levels to less than 4 mmHg. In the meantime, retrospective investigations attempting to associate crew symptoms with elevated CO 2 levels over the life of the International Space Station (ISS) are underway to determine if this level is sufficient to protect against health and performance decrements. Anecdotal reports suggest that crewmembers are not able to perform complex tasks as readily in spaceflight as they were able to during ground-based training. Recently the effects of CO 2 on decision making have been investigated. Using data from this one study, we show that there are obvious adverse effects of CO 2 exposures on decision making above 1.5 mmHg. The implications and limitations of this study are paramount in determining future CO 2 SMACs for human spaceflight, both aboard the ISS and in exploration-class missions. NomenclatureAGARD = Advisory Group for Aerospace Research and Development BMD = benchmark dose cfm = cubic feet per minute EVA = extravehicular activity ISS = International Space Station mmHg = millimeters of mercury ppm = part per million SMAC = Spacecraft Maximum Allowable Concentration SD = standard deviation SMS = Strategic Management Simulation

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

“…Generally, the post‐exposure data were used to investigate the effects of CO 2 exposure concentrations on human responses in most previous studies 10‐13,24‐27,30 . In this study, the human vigilance and sentiment responses were obtained both before and after each CO 2 exposure session.…”

“…Generally, the post-exposure data were used to investigate the effects of CO 2 exposure concentrations on human responses in most previous studies. [10][11][12][13][24][25][26][27]30 In this study, the human vigilance and sentiment responses were obtained both before and after each CO 2 exposure session. The post-to-baseline ratios of human response data were used for the GAMM analysis, which was conducive to eliminate the baseline differences and to better explore the effect degrees of elevated CO 2 concentration on human vigilance and sentiment caused by the 4-hour exposure.…”

“…However, with further researches about the effects of CO 2 exposure on human response, for example, the subjective perception, task performance, and physiological response, many scholars indicate that CO 2 concentration is not only a proxy of the ventilation, but a key pollutant that affects indoor environment quality and human performance 9 . The detrimental effects of elevated CO 2 concentration on human decision‐making ability have been reported even at the acute CO 2 exposure as low as 1000 ppm, 9‐13 much lower than the current 8‐hour occupational exposure limit of 5000 ppm by the Occupational Safety and Health Administration (OSHA) 14 and the American Conference of Governmental Industrial Hygienists (ACGIH) 15…”

“…scholars indicate that CO 2 concentration is not only a proxy of the ventilation, but a key pollutant that affects indoor environment quality and human performance. 9 The detrimental effects of elevated CO 2 concentration on human decision-making ability have been reported even at the acute CO 2 exposure as low as 1000 ppm, [9][10][11][12][13] much lower than the current 8-hour occupational exposure limit of 5000 ppm by the Occupational Safety and Health Administration (OSHA) 14 and the American Conference of Governmental Industrial Hygienists (ACGIH). 15 Vigilance refers to the ability of organisms to maintain their focus of attention and to remain alert to stimuli over prolonged periods of time.…”

Guiding Requirements for Designing Life Support System Architectures for Crewed Exploration Missions Beyond Low-Earth Orbit

“…Recent developments pertaining to the need to control the CO2 partial pressure to levels well below the published 1000-day SMAC of 8990 mg/m 3 (3.8 mm Hg) must be considered. 33,34 Controlling to CO2 concentrations <4730 mg/m 3 (2 mm Hg) may be necessary if crew health and performance observations aboard the ISS are confirmed by ground-based studies. 35…”