View Full Version : How long could someone survive with this much air?

09-01-2018, 07:43 PM

I'd like to know how long someone could survive in a large-ish bathroom-sized room that had been sealed in an airtight fashion. I'm not too bothered about the exact size of the room as I can change it as required but let's say something that was 4m by 4m.

The character has a water supply and some food to hand.

Thank you in advance!

09-01-2018, 07:50 PM
If it's truly airtight (that's hard to accomplish in a room generally), not long. Someone else can do the math (you can do the math to figure this at a general conversion rate and general atmospheric composition), but they're going to be in trouble waaaaaaay before water or food becomes any kind of issue. Remember it's not 'running out of air,' it's that you're killing yourself, converting the air you do have to CO2.

ETA: I looked to see if someone else had done the math (https://io9.gizmodo.com/5861679/how-long-would-you-survive-in-an-airlock), heh. Depending on what they're doing and how panicked they are, half a day, a day...

09-01-2018, 08:29 PM
Agree that it would be rising CO2 levels that would kill you before lack of oxygen becomes an issue, but I don't know the amount of time it would take. If it helps, normal air is 0.04% carbon dioxide and the air you breathe out is about 4% carbon dioxide.

NASA might have some data related to this sort of thing, because they're researching how they could build a human colony in Mars in the futhre and they need to know how much O2 humans need and how much CO2 you'd need to get rid of to support humans living in completely isolated ecosystems. Plus spacecraft and space suits need ways to remove the CO2 from the air that astronauts breathe - they must know how much needs to be removed in what time, and therefore how long humans can survive without CO2 being removed, etc. This could give you the data you need to work out how long she'd remain in a state of useful consciousness in this completely sealed room, plus how long before she'd fall completely unconscious and how long she'd take to die.

ETA: just seen the link in Cornflake's edited bit, it wasn't there when I started this reply... too much multitasking lol

09-01-2018, 11:11 PM
Wow, thank you both. I did google it myself and came up against some less than useful nerdery and some nasty foresnsic stuff I had not wanted to see!
The i09 site has some useful comments about how it would feel too.

NASA website is a brilliant idea, character is not in space, nor in a spaceship airlock, but they are sealed in. There are some plants in there too...

Thank you, very useful.

09-02-2018, 02:04 AM
You're looking at the wrong end of your problem. Your character needs to survive for X number of hours (days) before dying from asphyxia from carbon dioxide poisoning. Once you know what X is, you can calculate approximately how large a room you need. If you need a longer time to survive than the room you want to use, you make the room partially airtight (much easier to achieve).

But in any reasonable size enclosure, you're talking hours, not days, and you get a gradual effect. Look up the effects of carbon dioxide poisoning. You'll initially start with a headache, with confusion and gradually unconsciousness. Remember the survival time is longer than the consciousness time.

Jim Clark-Dawe

09-06-2018, 01:01 PM
Hehe, yes the room size is adjustable to fit plot needs. Thanks for the advice!