Carbon dioxide poisoning can have many adverse effects on a person, from headaches, to an increased heart rate, to death. In space these effects, especially ones that can affect behavior, are augmented due to the close crew contact and highly confined spaces.
This journal article by Dr. John T. James, and Dr. Ariel Macatangay explores the many troubles required to keep the air in the ISS safe for the astronauts to breathe.
The ISS currently uses a CO2 removal system called Vozdukh. The Russian Vozdukh absorbs carbon dioxide into an absorption bed and then vacuum desorbed into space. However, if the crew on the space station requires more oxygen, this can be supplemented using lithium hydroxide canisters. These canisters are the only carbon dioxide removal system used in the Space Shuttles, and rely on a reaction between the lithium hydroxide and carbon dioxide. This reaction can be modeled by the equation 2LiOH + CO2 → Li2CO3 + H2O. The main downfall of these canisters is that they do not regenerate and need to be replenished. To know how much lithium hydroxide is needed, NASA uses measurements of the amount of carbon dioxide exhaled by its astronauts (about 1kg per day), and uses stoichiometric calculations to determine the amount required to keep carbon dioxide levels below the exposure limits.
I personally just think it's awesome that we can put these white pellets into space and they remove a deadly toxin from the air. And the carbon dioxide removal is so important that when the explosion crippled the Apollo 13 Command/Service Module, the main concern was to be able to create breathable air for the astronauts.
So, do you think these lithium hydroxide canisters are necessary? Or should we take them out of the space stations?
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