What is the lowest % of oxygen in the air that humans can remain conscious?

Question

Air contains about 21% oxygen. Ignoring increased levels of carbondioxide; At what level would we lose awareness and what is the minimum we could remain alive? Is there an upper limit ?

Answer 1

a) According to NASA the average person needs 0.84 kg of O2 per day (day and night activity).

(b) According to MadSci: The amount of air breathed by an average adult varies from 6 Litre/minute (when at rest) to 50 Litre/minute after hard exercise. So, at rest the amount of Oxygen absorbed by the blood in the lungs is 300 milliLitre/minute to 3,500 mL/minute.
My Calculations for a person at rest: In 1 day the volume of O2 absorbed by a person at rest is 300mL/minute x 60 minute/hour x 24 h/day = 432,000 mL/day or 432 L/day. Since the mass of 1 mole of O2 is 32 gram and 1 mole of any gas has a volume of 22.4 L, the number of mole/day is 432 L/day / 22.4 L/mole = 19.28 mole.
The mass of O2 needed per day is then 19.28 mole x 32 gram/mole = 617 gram or 0.617 kg of Oxygen per day, which is less than the NASA figure.

My Calculations for a person doing hard exercise all day: In 1 day the volume of O2 absorbed by a person at rest is 3,500 mL/minute x 60 minute/hour x 24 h/day =5,040,000 mL/day or 5,040 L/day. Since the mass of 1 mole of O2 is 32 gram and 1 mole of any gas has a volume of 22.4 L, the number of mole/day is 5,040 L/day / 22.4 L/mole = 225 mole.
The mass of O2 needed per day is then 225 mole x 32 gram/mole = 7,200 gram or 7.2 kg of Oxygen per day, which is much more than the NASA figure. This is an unrealistic figure because a person doesn't do hard exercise day and night, but it does give an upper limit to Oxygen consumption for the average person.

Answer 2

Due to presence of carbondioxide the level for oxygen will be 16%

Answer 3

It is not so much the % in air as the partial pressure of the oxygen. For example air pressure at sea level is 14.7 lb/in^2 so the pressure of the oxygen is about 3 lb/in^2 . Astronouts have used a pure oxygen atmosphere of about that pressure to work with.

Airplane pilots are in danger above 12000 feet so if you know the air pressure at 12000 feet you can figure the partial pressure of oxygen that would be available.

Answer 4

Why submit a similar question two times? the respond won't substitute... in line with danger... it relies upon on how elastic your epidermis is. Your epidermis is in consequence, a balloon. If all of sudden in a vacuum, the 1st factor is the air leaves your lungs. next, you initiate dropping warmth by utilizing radiation. the indoors warmth of your physique will reason water on your physique to "boil", vaporize because of warmth and absence of rigidity. Water will boil at room temperature if the atmospheric rigidity is decreased to a million PSI from the traditional 15 PSI. in case you tried to hold your breath, then it extremely is achieveable you will possibly rupture your lungs, yet once you probably did no longer, the air might pass away and then the indoors warmth of your physique might start to boil the water, from the outdoors first, progressing inwards. So, in the experience that your epidermis is robust adequate and elastic adequate, you will possibly bloat, yet no longer explode. you will no longer pop like a balloon with a pin, yet your epidermis could rip aside because of indoors vapor rigidity. you would be ineffective long earlier any water starts to boil from loss of oxygen. in the action picture, 2001, an area Odyssey, Dave, the main character enters an area pod and leaves the invention. He has his area healthful yet no longer the helmet. HAL refuses to allow him returned interior while he returns. So, Dave comes to a decision to pass into manually. He opens an air lock and turns the pod around so the get away hatch faces the open airlock. He then "blows" the hatch. The outrush of air propels him into the airlock the place he grabs an emergency lever to close and pressurize the airlock. NASA went on checklist as asserting this maneuver grew to become into thoroughly real looking and achieveable. the full quantity of time under vacuum in the scene grew to become into approximately 15 seconds from the time the hatch blew till the airlock grew to become into close and air grew to become into flooding the area.

Answer 5

We need more oxygen otherwise everyone's gonna get disease, the rates are high already, but the government don't even see planting trees as an important issue. It will be like the rush with global warming when they eventually realize & then it could be too late.

Answer 6

7-10%

Answer 7

16 is lower and there is no uper

Answer 8

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