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Surprised to see that the standard CO2 level on the space station is 4000 ppm

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Re: Surprised to see that the standard CO2 level on the space station is 4000 ppm

#11

Post by lazide »

pkulak wrote: post #5

It's my understanding that the real reason we measure co2 is because it's easier to measure. Obviously, o2 is what's important, but they correlate when co2 comes from breathing out, so it's fine to just measure one. Maybe if you maintain a good o2 level, the co2 level just isn't that important? But on the flip side... co2 is the only thing your body measures too! Which is why taking a breath of co2 from a soda bottle…

Not really - oxygen is a large percentage of the atmosphere (21%), and co2 becomes noticeably bad at tiny fraction of a percent - 1000 ppm == .1%

So even 2000-3000 ppm, which is quite noticeably stuffy and uncomfortable is only .2-.3%.

Oxygen percentage isn’t going to be notably lower in these scenarios. At most 20%, though the stoichiometry makes it easier to calculate exactly.

Re: Surprised to see that the standard CO2 level on the space station is 4000 ppm

#12

Post by marko_oktabyr »

kibitzor wrote: post #7

Related reading "I’m living in a carbon bubble. Literally."[0] which has a lot of great basic charts and graphs on everyday data related to CO2. Information in this reading that is relevant to 4000 PPM on the Space Station -Typical CO2 concentrations can reach 4000 ppm in a car -"On the International Space Station, the odds of a crew member reporting a headache double for every 1300 ppm increase in CO2 concentration…

NASA’s Office of the Chief Heath and Medical Officer has published a number of technical briefs [0] that cover a variety of human spaceflight related risks and topics. In particular, they have one for carbon dioxide [1, PDF warning] with some references that may interest you.

[0]: https://www.nasa.gov/ochmo/health-operations-and-oversight/h... [1]: https://www.nasa.gov/wp-content/uploads/2023/12/ochmo-tb-004...

Re: Surprised to see that the standard CO2 level on the space station is 4000 ppm

#13

Post by wahern »

lazide wrote: post #11
pkulak wrote: post #5

It's my understanding that the real reason we measure co2 is because it's easier to measure. Obviously, o2 is what's important, but they correlate when co2 comes from breathing out, so it's fine to just measure one. Maybe if you maintain a good o2 level, the co2 level just isn't that important? But on the flip side... co2 is the only thing your body measures too! Which is why taking a breath of co2 from a soda bottle…

Not really - oxygen is a large percentage of the atmosphere (21%), and co2 becomes noticeably bad at tiny fraction of a percent - 1000 ppm == .1% So even 2000-3000 ppm, which is quite noticeably stuffy and uncomfortable is only .2-.3%. Oxygen percentage isn’t going to be notably lower in these scenarios. At most 20%, though the stoichiometry makes it easier to calculate exactly.

> So even 2000-3000 ppm, which is quite noticeably stuffy and uncomfortable is only .2-.3%.

That's certainly the consensus internet "fact", which is presumably why this tweet was posted in the first place. Which poses the question, are astronauts on the space station uncomfortable?

Re: Surprised to see that the standard CO2 level on the space station is 4000 ppm

#14

Post by lazide »

wahern wrote: post #13
lazide wrote: post #11

Earlier quoted context omitted.

Not really - oxygen is a large percentage of the atmosphere (21%), and co2 becomes noticeably bad at tiny fraction of a percent - 1000 ppm == .1% So even 2000-3000 ppm, which is quite noticeably stuffy and uncomfortable is only .2-.3%. Oxygen percentage isn’t going to be notably lower in these scenarios. At most 20%, though the stoichiometry makes it easier to calculate exactly.

> So even 2000-3000 ppm, which is quite noticeably stuffy and uncomfortable is only .2-.3%. That's certainly the consensus internet "fact", which is presumably why this tweet was posted in the first place. Which poses the question, are astronauts on the space station uncomfortable?

I’ve used co2 monitors (calibrated) and it’s quite noticable (as in ‘why is it so stuffy in here?’ then check and ‘ah, duh’).

The astronauts likely just get used to it.

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