# What would happen if the air we breathed was 100% Oxygen?



## Diamondeyes (Sep 19, 2011)

What would happen if the air we breathed was 100% Oxygen, rather than 20.95%?
(ignoring the fact that CO2 must be expelled and be a part of the whole make up)


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## Simpson17866 (Dec 3, 2014)

We wouldn't feel any biological difference – we spent a billion years evolving to survive on a planet with ≈20% oxygen, so we could've spent a billion years evolving to survive on a planet with ≈100% oxygen – but fires would start a lot more easily.

Which would bring the proportion of oxygen down and carbon dioxide up. If the atmosphere started out as 100% oxygen, and then burned the Earth's biomass until 50% of the air was oxygen and 50% was carbon dioxide, fires would *still* start more easily in a 50% oxygen atmosphere than in a 21% oxygen atmosphere, and that's only 1 component of the Fire Triangle.

Fire requires 3 things: Heat, Oxygen, and Fuel. Carbon dioxide levels fluctuating on the level of hundreds of parts per million are enough to create temperature differences comparable to the differences between modern day versus the ice age, but in the opposite direction.

Carbon dioxide measuring in the hundreds of thousands of parts per million would roast the Earth so viciously that fires would start easily with even *less* oxygen than we have now. We would still have *even more* oxygen in the 50:50 scenario than we do now, so coupled with the horrifying temperatures, the entire planet could concievably be one large firestorm.

The only chance for survival would be after all of the potential fuel had burned away, leaving the Earth as a hellscape of thousand-degree carbon dioxide like Venus but one without any fires.

Which, fun fact, means that I was lying to you about this being a chance for our survival.


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## Stopping By Woods (Jun 20, 2016)

Death of all flora and a highly flammable atmosphere.


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## vhaydenlv (May 3, 2017)

If the oxygen just suddenly jumped up to 100%, if I remember correctly, it would be toxic to humans.


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## dulcinea (Aug 22, 2011)

You'd have giant insects for a while before everyone died of oxygen toxicity and the slightest spark ignited the entire planet of fire.


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## Simpson17866 (Dec 3, 2014)

dulcinea said:


> You'd have giant insects for a while before everyone died of oxygen toxicity and the slightest spark ignited the entire planet of fire.


 You're right! How, with all of the hellfire and brimstone, could I have forgotten about the monstrous locusts :laughing:


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## Lakigigar (Jan 4, 2016)

Not to mention that Earth would be an ice planet. Not only would "all flora" have been gone, we would have no greenhouse gases anymore. Despite trees not being able anymore to filter co2, it would tip the balance towards a colder climate, a freezing planet or ice planet. The Earth would be a snowball earth with completely covered by thick glaciers that would lock up all our chemical gases (if we would still have them). Technically, it could become so cold that all the oxygen would condensate or even freeze. Our atmosphere would be gone. The only possible oceans could be formed deep underground. Earth would be unrecognizable and the consequences would lead to even more consequences but Earth would probably look like a combination of mars, pluto, enceladus and europa. 

What would happen more? metal would rust easier, therefore creating huge rust deposits on the ocean floor and creating more continental crust or landmasses. The forest fires would create large coal deposits. Everything would burn, even steel. And actually even the atmosphere would burn, it would all be lit on fire. Everything you know of. The atmosphere would be gone. The oceans would damp before everything would freeze to death.

Insects (and animals) would grow larger (but they wouldn't have the time for it). marine life would migrate to the deep sea since "the anoxic conditions" would be favorable with increased oxygen levels, exterminating existing life there to be filled with the dominant life forms in the higher seas (but again, they wouldn't have the time for it).

Even 50% and more would be inhabitable and 30-35% would have large consequences (larger animals and insects, more forest fires, very cold planet, probably too cold to sustain life in large areas, more rust and coal deposits, rapid evolution (both plant, microbiological, animal and marine life), the migration of marine life to the deep ocean, decreased sea levels, ... )


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## ShatteredHeart (Jul 11, 2014)

only a small fraction of air is oxygen, most of it is actually nitrogen


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## Simpson17866 (Dec 3, 2014)

ShatteredHeart said:


> only a small fraction of air is oxygen, most of it is actually nitrogen


 And isn't that a good thing :wink:


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## Lakigigar (Jan 4, 2016)

Simpson17866 said:


> And isn't that a good thing :wink:


no it's not, we better be extinct.


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## Hero of Freedom (Nov 23, 2014)

dulcinea said:


> You'd have giant insects for a while before everyone died of oxygen toxicity and the slightest spark ignited the entire planet of fire.


Giant insects would be the worst phenomenon. You would then need an actual crossbow and not just a 'toothpick crossbow' or 'bug-a-salt gun'. I have one but accuracy is very hard to predict seems.


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## Jonn (Mar 17, 2014)

1. you would die
2. you would get poisoned
3. you would explode.

Now why?
1. You would die from your cells catching fire. 
What you forget is that nitrogen, which makes up 70% of the atmospheric air actually stops fire from spreading or even igniting.
With 100% oxygen, there would be absolutely no restrictions on what would catch fire, grinding your hands to make a little more heat in winter would make the air around you ignite. but your cells do "ignition" all the time by burning fat/sugar/protein inside of them, with only oxygen those processes would produce flames and your cells would burn from the inside.

2. Your lungs can't handle more than 20% oxygen, they're actually not build to take in 30% or 40% oxygen, you could evolve to take in less air, meaning a lower density of air, though still in the same percentages. The himalayans take in a lower density air, but it is still 20% oxygen.
Some 100 mio. years ago the dinosaurs lived with a 30% oxygen atmosphere, their bodies in turn were huge. The oxygen percentage in the atmosphere had something to do with their scale, in that sense I could tell you our lungs would have to be same size as the dinosaurs for us to be capable of taking in 30% oxygen.

3. The pressure in an 100% oxygen atmosphere is also different, which means that our bodies would explode or implode on the change in atmosphere. At least our hearts would have constant heart stops or heart attacks for as long as we kept our mouths, ears, eyes or nostrals open.


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## Flow Ozzy (Nov 7, 2015)

I read somewhere that people will become taller, :S


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## Fumetsu (Oct 7, 2015)

Huh. I was aware of most if these situation but why larger insects? Sonething like ( exo) skeletal density?


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## Flow Ozzy (Nov 7, 2015)

Fumetsu said:


> Huh. I was aware of most if these situation but why larger insects? Sonething like ( exo) skeletal density?


https://www.livescience.com/1083-oxygen-giant-bugs.html


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## Hero of Freedom (Nov 23, 2014)

Crotch Asphyxiation said:


> I read somewhere that people will become taller, :S


Attack on Titan would become real? Use a grappling hook and special blades designed to take down massive titans ravaging your city/town and eating people.






In this case what would you do @Lemmy or anybody else here who's a fan of this stuff XD?


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## Eren Jaegerbomb (Nov 13, 2015)

Defender of Light said:


> Attack on Titan would become real? Use a grappling hook and special blades designed to take down massive titans ravaging your city/town and eating people.
> 
> 
> 
> ...


There actually used to be giant people way back in the day, but not much is said about it, or known about it, but they existed.

If people became really tall giants- well they're still people and not mindless titans, but I would watch out for them. Gives a new meaning to people "walking over others" in life. They could just literally squish other people to get their way if they wanted to.


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## HAL (May 10, 2014)

Another thing I've just remembered is that the human body regulates its respiration via CO2 levels.

For example, people who hyperventilate before doing a long swim underwater risk death because the hyperventilation expels too much CO2, causing the body to not realise when oxygen levels run low during the swim, then a sudden blackout occurs. Essentially, CO2 levels are what give you that pressing need to breathe.

In a 100% oxygen planet, we'd all have no sense of when it was time to take another breath. We'd sit there feeling hunky-dory for a couple of minutes then just... pass out. And then, because there's still no CO2 in the air to trigger the desire to breathe, we'd carry on not breathing even in the passed out state. And then we would die.


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## chad86tsi (Dec 27, 2016)

Early astronauts were in a 100% oxygen environment for days at a time, but the air pressure was 1/4 of normal so the density of 02 was about normal. this was done to save weight. The stopped doing that some time after a fire destroyed Apollo 1 during preflight testing, killing 3 astronauts.


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## angelfish (Feb 17, 2011)

I don't think anyone has mentioned blindness... besides death, fire, etc.... that is a danger of too much oxygen...


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## martinkunev (Mar 23, 2017)

Oxygen is very reactive and in too high concentration will have serious effects on the body. Oxygen is bad for the eyes and lungs.


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## atamagasuita (May 15, 2016)

We're gonna die. Earth wouldn't even exist


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## atamagasuita (May 15, 2016)

Defender of Light said:


> Attack on Titan would become real? Use a grappling hook and special blades designed to take down massive titans ravaging your city/town and eating people.
> 
> 
> 
> ...


Imma super fan ;p hihi


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## Hero of Freedom (Nov 23, 2014)

atamagasuita said:


> Imma super fan ;p hihi


Aside from that you would see people going "OMG HELP HELP, SOMEBODY PLEASE HELP *a high pitched*-ARRRRRRRRRGH!" Before hearing a squish sound then seeing blood everywhere if they get grabbed by a titan. This would happen alot for anyone who joined the survey corps division.

Also if Trump built his wall during that event, it would be fitting.


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## Angelo (Aug 17, 2016)

First they say too much water can kill you now they're saying too much oxygen can kill you!? Fucking scientists, I bet they'll try to tell us 'eating too many bananas can kill you' or something stupid like that.


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## atamagasuita (May 15, 2016)

Defender of Light said:


> Aside from that you would see people going "OMG HELP HELP, SOMEBODY PLEASE HELP *a high pitched*-ARRRRRRRRRGH!" Before hearing a squish sound then seeing blood everywhere if they get grabbed by a titan. This would happen alot for anyone who joined the survey corps division.
> 
> Also if Trump built his wall during that event, it would be fitting.


Yeah. I actually bought some titan action figure as well. I love this thing:


* *


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## Maybe (Sep 10, 2016)

Angelo said:


> First they say too much water can kill you now they're saying too much oxygen can kill you!? Fucking scientists, I bet they'll try to tell us 'eating too many bananas can kill you' or something stupid like that.


Bananas are slightly more radioactive than most food, so yes if you eat too many you'll die.


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## Maybe (Sep 10, 2016)

Diamondeyes said:


> What would happen if the air we breathed was 100% Oxygen, rather than 20.95%?
> (ignoring the fact that CO2 must be expelled and be a part of the whole make up)


https://en.wikipedia.org/wiki/Hyperoxia


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## tanstaafl28 (Sep 10, 2012)

It would kill you (not to mention a single spark would ignite the atmosphere and destroy everything). Plant life would die because it needs Co2, not oxygen. 

Our blood has evolved to capture the oxygen we breathe in and bind it safely to the transport molecule called haemoglobin. If you breathe air with a much higher than normal O2 concentration, the oxygen in the lungs overwhelms the blood's ability to carry it away.

The result is that free oxygen binds to the surface proteins of the lungs, interferes with the operation of the central nervous system and also attacks the retina.

Contrary to popular myth, hyperventilating air at ordinary pressures never causes oxygen toxicity (the dizziness is due to CO2 levels dropping too low), but breathing oxygen at pressures of 0.5 bar or more (roughly two and a half times normal) for more than 16 hours can lead to irreversible lung damage and, eventually, death.​
Why does breathing pure oxygen kill you?


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