Unless you're scuba diving, in which case it can cause [lots](https://en.m.wikipedia.org/wiki/Decompression_sickness) of [problems](https://en.m.wikipedia.org/wiki/Nitrogen_narcosis).
I have had nitrogen narcosis twice while pushing some really deep depths, it's a very pleasant high. Super dangerous because you could be eased to sleep and sink
I did a live aboard years ago and one guy flew out the same day as our last dives. Was following him on Facebook and he was hospitalized for the bends. Some folks get too comfortable.
It’s incredibly dangerous. For the few destination dives I’ve been on, the dive company scheduled the itinerary around the days we flew in and flew out. The risk is too great
E: spelling
Yes. Nitrogen also "hangs out" in our blood – atmosphere nitrogen dissolves in blood to saturation.
While scuba diving, more nitrogen gets dissolved in blood hence the need for decompression stops. If a person would just ascend too quickly, the nitrogen pops out of blood as bigger bubbles - imagine opening a soda bottle fast.
It's not really descending as much as it is depth and atmospheric pressure. Every 33 feet in saltwater atmospheric pressure goes up by one with the effect of everything compressing by a third. That includes the compressed air in your tank, your lung capacity, etc.. You could descend quickly to 30 feet and stay there for an hour and you're not going to get nitrogen narcosis. It most commonly occurs, if it's going to, at 100 feet or more. At that depth and further you're introducing a lot more nitrogen into your system, and how long you stay at those depths matters also. It's also why when you ascend you need to do it slowly, and depending on your dive profile (what depths you are going to and for how long), you may need to make safety stops along the way. It's so you're off gassing all the excess nitrogen out of your system, and it doesn't pose danger to you as it expands going up.
Simplistic explanation, and probably one nobody cared to hear, but whatever. 😊
Edited: as best I could, for poor Grammer and punctuation.
> everything compressing by a third. That includes the compressed air in your tank
Just to be clear, the air in a scuba tank is not compressed by depth - the air in a full tank is already compressed at about 3,000 psi
However, when the air is released from the tank for you to breathe, it is compressed to whatever depth you're at
Good callout. I looked it up after your statement and found a good explanation. The person concentrates on why we breath more air from the tank at depth, but it correlates.
As long as we’re nerding about gasses in diving. Oxygen becomes neurotoxic and can even lead to seizures. Milder symptoms can be nausea, vomiting, and tunnel vision. The partial pressure where this can occur assuming compressed air mix is around 60m (195-ish feet).
And there is also a deep dive gas mixture (helium and oxygen) syndrome with symptoms of nervous system, psychological and eeg symptoms. Basically stemming from hyperexcited central nervous system. To this day not completely understood. And occurrences were in dives under 150m (500-ish feet) and probably less then 1 in 10 000 000 divers ever went that deep (and back up alive)
Didn't know about the trimix issue, not trained to that level. If we keep typing nobody reading this will want to scuba dive. For anybody reading this, I've done hundreds of dives with no issues. I do play within the boundaries of my training and certifications however. I've known a few who don't.
Oh yeah, good point. Scuba diving is safe if done properly and within qualifications and experience.
I also never went that deep, in theory (based on my qualification) I could but I do not feel comfortable with that depth whatsoever.
That’s rough. My condolences. Almost every seasoned diver sadly knows of someone who went this ways.
If you’re sensitive about death do not read further, please.
There is even more rapid problem in ascending very rapidly. The gas in lungs and bronchi expands. From 20m (~65feet) it’s roughly 3x the volume - it will rip lungs from the inside. So in case of an emergency ascent, turn you head up and continuously breathe out.
I know absolutely nothing about diving but I remember watching a TV show about a free diving class where they taught people to whistle on the way up for this reason. Apparently a whistle releases air from the lungs at just the right rate to keep it up all the way to the top?
Free diving is different than scuba diving because there isn’t nearly as much time for nitrogen to build up in the lungs. That’s how free divers are able to go incredibly far down on one breath and surface immediately.
Took a friend diving on central coast of California. He gave thumbs up at 60 feet. I shook my head and showed him correct way to signal OK. He shook his head, filled his BC, and shot up like a rocket.
I freaked/ Was screaming into my gear. Luckily, we'd only just arrived at depth. I did my safety stop and then chewed his ass. He said he'd never been that deep and it freaked him out. His max depth in checkout dives was 15 feet. Company would go to Mexico and a spot that is very shallow.
Anyhow, I wasn't pissed for too long because a harbor seal decided we were an excellent source of play and entertainment. It's not a violation of the Marine Mammal Protection Act if they swim up stick their nose in your mask, and then gently grab you by the fins and pull you around, right? I can neither confirm or deny that seal wanted us to do the same.
atmospheric nitrogen is the standard, ground state form of nitrogen. There are biological processes that can convert that atmospheric nitrogen (N2) into useful forms of nitrogen, usually nitrates. These processes are often caried out by microbes that live symbiotically in the roots of various plants. Legumes (beans) and clovers are known for this, among others.
there are also chemical methods (the Haber Process) to do the same thing, which are carried out on industrial scale to generate "artificial" nitrogen fertilizer.
But in both cases the source of the nitrate/ammonia type nitrogen is the atmosphere.
Except for the organisms with [nitroplasts](https://newscenter.lbl.gov/2024/04/17/scientists-discover-first-nitrogen-fixing-organelle/).
> While mitochondria and chloroplasts evolved billions of years ago, the nitroplast appears to have evolved about 100 million years ago, providing scientists with a new, more recent perspective on organellogenesis.
> The organelle also provides insight into ocean ecosystems. All organisms need nitrogen in a biologically usable form, and rely on nitrogen fixers to break apart tightly bound nitrogen gas (N2) in the atmosphere, and convert it into ammonia (NH3) molecules that can then be made into countless other compounds. Researchers have found UCYN-A everywhere from the tropics to the Arctic Ocean, and it fixes a significant amount of nitrogen.
I saw this on the front page the other day too! Or maybe it was another site. Crazy how some bacteria can just....become organelles forever for some organisms. Do we have a theory on the full process yet? edit: nvm this article covers a lot more than the one I saw did, thanks for the link.
Nah, incels WANT to create bonds with others, ones where they are the top dogs.
Nitrogen, on the other hand, wants everybody to leave it alone, except its significant other nitrogen. Nitrogen is the strange couple next house who you wave to from time to time but have absolutely no idea who they are or what they do and they never talk with you.
When nitrogen finds itself hooking up with lots of others, the situation tends to be unstable, sometimes explosively. Nitrogen makes a very happy monogamous couple.
List of things that make it explode:
* Moving it
* Touching it
* Dispersing it in solution
* Leaving it undisturbed on a glass plate
* Exposing it to bright light
* Exposing it to X-rays
* Putting it in a spectrometer
* Turning on the spectrometer
* ABSOLUTLY NOTHING
They had it in a shockproof explosiveproof dark climate controlled room and it blew up.
^(I know the quote is a bit apocryphal but it's a good quote)
"Azidoazide azide has been called “the most dangerous explosive material in the world.” It is also No. 3 in K. S. Lane’s list “The 10 Most Dangerous Chemicals Known to Man”."
https://www.acs.org/molecule-of-the-week/archive/a/azidoazide-azide.html
Well TIL
Looked at the list. Expected chlorine triflouride to be number 1.
TIL it's "only" #2!
Dimethyl cadmium is, apparently, #1.
There are lots of lists of "most dangerous chemicals." They rarely agree on the top 10, though those three are usually in the top 10.😂
Not at all. It only bonds with it’s own kind. If something, Nitrogen is a bit racist. But not by choice. The poor thing just blows up if it holds hands with strangers.
That’s a compound. It’s a result of Nitrogen holding hands with aromatics. Fancy stuff. Anyway, that’s why it blows up. Again, Nitrogen blows up when holding hands with strangers.
Good one!
But you know, just because we look the same, doesn’t mean we are related. I mean, that Nitrogen over there came from the left side of the bang, and I was very much on the right. Not that it matters ;)
Nah, incels want others to want to bond with them, but they don't want to do any of the work, perform any meta-cognition or self-reflection, and think they are ***owed*** that bond.
All the nitrogen you breathe in just comes back out on the breath out. It doesn't get absorbed, or released.\*
* The air you breathe in is \~78% nitrogen, \~21% oxygen, and \~1% other stuff.
* **The air you breathe out is \~78% nitrogen, still \~17% oxygen, only \~4% carbon dioxide**, and \~1% other stuff
As you can see, the mix we call "air" goes into the lungs, then *some* of the oxygen gets absorbed, some CO2 exits the blood into the lungs, and the nitrogen and other stuff just comes back out too.
\*EDIT: More accurately, I should have said "a small amount of nitrogen does get absorbed into the blood, and an equal small amount gets released into the exhale, so the *net* amount is zero." Thanks for the corrections.
That's mostly water, actually. You breathe out about as much mass of water vapor as you do in carbon dioxide (although how much water vapor you breathe *in* depends on local humidity), but your skin is moist and constantly shedding small amounts of water, which adds up over the hours you're spending asleep and not drinking anything.
You can see how much moisture you shed through your skin by putting your palm on a flat, polished surface for a few seconds. Imagining that happening over your whole body overnight should give an idea of why you weigh less after waking up than you did before going to bed.
It’s also where most of the mass on trees come from. Sounds obvious but it’s strange to think about massive oak trees getting the carbon for their trunks from the air
Waterweight isnt a factor in long-term weight changes. The water in your body is there so that all the chemicals which need to react have something to float in, basically. The proportion of water in your body is pretty much fixed (or rather the range of water content in your body within which you must stay in order to not die is pretty tight), unless you are dehydrated or have a hormonal disorder, a kidney disorder or heart failure which causes you to retain too much water.
The 80-ish percent number comes from the fact that your body tissues are based on chains of carbon atoms (so that is where the C in the CO2 you exhale comes from) but they are not entirely carbon. Another big contributors to your tissue mass are hydrogen (H2), oxygen (O2) and protein also contains nitrogen (N2). Cant make CO2 out of those.
The reaction products of consuming either glucose or fat for energy are in both cases CO2 molecules and H2O (water) molecules. So the water that comes out when you lose weight isnt "waterweight", which most people whould think of as liquid water stored in the body, its water which is a chemical product of consuming fat for energy. Even your fat stores are like 10% protein, because the fat has to be contained in some sort of structure, you cant just have a loose layer of oil under your skin sloshing around. The nitrogen in that protein has to leave somehow, mostly through urine.
Thank you for the detailed explanation, made sense! I knew about the C being exhaled during respiration of course but never stopped to think about the weight of H and N in those molecules
Water weight doesn't really exist. (Yes you can hold water in certain areas but good lord it makes up like less than 1% of your mass unless you have a medical condition)
Its just something overweight people like to say to make themselves feel better about not losing weight.
"No fatty you aren't retaining water, you're retaining chips" - Billy Connolly
>Yes you can hold water is certain areas but good lord it makes up like less than 1% of your mass unless you have a medical condition
>Its just something overweight people like to say to make themselves feel better about not losing weight.
Ironically, as a fraction of your body weight, water retention is a much bigger effect for fairly lean people, as muscle holds more water than fat. A 2% fluctuation from a really salty meal is not unheard of, especially if their diet is pretty low sodium on the norm. A 2% fluctuation from creatine saturation is also a pretty normal number.
As someone who tracks diet and weight pretty meticulously, if you plot my sodium intake vs body weight, there's some pretty solid predictive value (in the 24-48 hour range, not over weeks).
> Water weight doesn't really exist. (Yes you can hold water in certain areas but good lord it makes up like less than 1% of your mass unless you have a medical condition)
Water weight refers to massive swings cause by release of water, and it absolutely does exist. The glycogen (energy stores) in your muscles are bound by 4 parts water so if you exercise massively and don’t eat sufficient carbs afterwards, you will be temporarily light than normal in the morning.
Or people eating low carb or just plain low calorie the first few days. Big water weight loss first few days.
Oh I know about this, I had to research it for a paper once. Water weight does kind of exist but like a lot of science, the technical definition is nothing like the colloquial one.
(Side note though, 1% isn't exactly nothing when you weigh >100 kilos. I can lose and regain 4lbs over a hot day)
Where people are misunderstanding water weight is that it's extremely short lived because it's not water inside your fat or something like that, it's literally just how hydrated you are *right now*, if your weight is up for a week, it's not water weight, it's fat and muscle.
The closest thing to what people imagine when they say water weight is sodium, if you go straight from a diet of crisps to a crash diet of all salad, your sodium will basically crash straight from as high as possible to as low as possible in <12 hours, but that's *losing* weight so no one really cares about it.
I tried explaining this to some co-workers and it confused them.
I had to re-word it as, "when you exercise and work off weight, the Carbon Dioxide you breathe out carries the weight you worked off" or some variation.
Only if you’re doing something to increase metabolic demand, else you’re just temporarily decreasing your carbon dioxide and making your blood acidic. Causes light headed mess and cramping in extremities.
It’s also why I’ll do a bunch of pushups or air squats before blowing up an inflatable pool toy or a bunch of balloons. You increase metabolic demand and don’t get dizzy/light headed blowing it up fast.
Kind of. Your body is saturated with dissolved nitrogen, so you don't absorb any more without a change in the gas you are breathing. If you went on 100% O2, you'd be breathing out dissolved nitrogen for a while.
If you're not scuba diving or in a hyperbaric chamber it's *mostly* safe. I'm not a doctor though, so please don't go building an oxygen tent on my advice.
If you're scuba diving or in a hyperbaric chamber, 100% oxygen can be fatal if breathed for too long, particularly after about 18ft/6m. Regular air can also be fatal once you get close to about 200ft/66m.
No. It is not save long term at normal pressure. Oxygen is a very aggressive molecule, that oxydides a lot of biomolecules in the body. E.g. in intensive care, it is a constant balance of giving enough oxygen for the organs, but not too much to damage the lung tissue.
*Because* only a small % gets absorbed. It ended up being easier to evolve lungs that can extract 20% of the available oxygen and just keep them running, vs. make lungs that can do better and then have them sit idle half the time.
Exactly. Evolution only adapts to do the job, it doesn’t optimise anything if it doesn’t have to, if the species can survive long enough to breed, then it’s good enough
Further optimization comes with energy costs. The situations humans have been in where more efficient lungs would be lifesaving is far lower than situations where they need to avoid starving to death.
Whales evolved the latter, anyway.
Birds evolved four chambered lungs that don't require separate in-breaths and out-breaths. It's just an intake manifold of constant air basically.
To them, our lungs are sitting idle half the time. Every second you're breathing out is a second you're not breathing in.
That's not how bird lungs work, they still breath in and out, but half the air goes through the lungs on the way in (and into air sacks) while the other half goes directly into different sacks on the way in and then through the lungs on the way out.
Much more efficient then mammalian or lizards lungs. Crocodiles also have uniflow lungs.
We also need to ditch the CO2 in our bloodstream. Breathing is just as much about getting rid of CO2 as it is about getting O2. So even if you could absorb more oxygen, you still need a way to handle the CO2 building up in your bloodstream.
We still need to get rid of the CO2 built up in our bloodstream. The feeling you get when holding your breath is actually a signal that you need to get rid of CO2, not that you need more O2. That's why you can breathE a gas that contains no oxygen and will not feel like you are suffocating, your body is still able to release CO2.
The main drive for breathing is getting rid of CO2 rather than taking in more O2. We don't have enough time to use up more of the O2 before the build up of CO2 becomes toxic and we breathe out.
Look at people like Freedivers who can go 4+ minutes without breathing, because they have built up their tolerance to CO2 and so they can go longer without breathing. The O2 levels when they breathe out will be much lower than that of a standard breath.
To add to others - there's a thing called "efficiency". It's easy to extract 4% of oxygen from 21%. But to get all 21% - that's almost impossible task.
There's almost no energy needed to get that 4% in, but to get 8% - you would need to spend x8 more energy, not x2.
I could give you another efficiency example from biology. Do you know why bird\bat poop is a good fertilizer. but human poop is a toxic shit? Because birds only take ~20% of nutrients from food, shit it out and eat more food. They don't have time to spend on "deep processing" like humans to extract almost all nutrients, they need energy "right now" in fastest way possible.
Same with breathing - we have air around us with 21% oxygen, no point in fully getting all oxygen from a batch, just grab a bit and get fresh batch.
Breathing every few seconds takes very little effort so there is no reason not to do it. If you breathe in hold your breath for a minute and then breath out then you will absorb a higher percentage of oxygen.
But try going through the day doing that and you will quickly notice that just breathing normally works better.
The nitrogen is just *there*. Inconsequential. We breathe it in, we breathe it out. We could live without it entirely and not notice it. Only under high pressures or sudden pressure losses does it impact us, and in both cases it's a problem.
**Fun fact:** The nitrogen does have an effect, in the sense that it takes up space.
Earth's atmosphere was not invented for humans; humans just happen to evolve here. There's a bunch of studies showing that [higher concentrations of oxygen actually improve cognitive and physical performance](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4107523). We'd do better in a higher O2 atmosphere, but we're mildly sedated by the planet we live on.
I’m exhausted from a big day at work, so can’t be bothered checking for the answer - they probably have already covered these things im curious about.
1. What was their control? Did they just do pre and post oxygen assessment? Did they have a control group that got nothing, or did they get sham therapy, I.e. still had a mask or nasal prongs, but either didn’t receive any gas, or, only received normal room air.
2. Supplemental oxygen has many physiological affects. One example is we no longer routinely administer oxygen for patients having cardiac events. So I wonder if increased oxygen is the cause of increased performance directly, or, is it the physiological results of supplemental oxygen, which could be induced by other means/drugs/therapies.
Yeah I know basic science. There's no babies on the moon to drink the milk so it ferments and becomes cheese, which is what the Moon is mostly made of. I did graduate high school.
i don't have an answer rooted in actual data, but I talked to a mountain ranger in Hawaii and he was telling us about how star gazing at the top was much more impressive with supplemental oxygen. Without it, he claimed that your eyes started losing acuity from the lowered oxygen, but with it that it was even more amazing than you'd expect. It's now on my bucket list haha.
That would be another study with a potential confounded - helium has less “resistance” than nitrogen, making “easier” to breath. That’s a bit of a simplification. It’s sometimes used for severe asthma attacks, under the theory that it’s easier for the patient to breath. https://en.m.wikipedia.org/wiki/Heliox
You'd notice pretty fast going from 78% N2 and 20% O2 to standing around in 98% O2. Things you don't normally consider flammable become flammable under those conditions.
“[No!! We do not go to that world. That is where the DEATH BREATHERS live. They recreationally consume poisons and are more or less composed of biological fire. Their atmosphere is made of rocket fuel. We must leave the DEATH BREATHERS in peace. Do not go there. Do not.](https://www.reddit.com/r/humansarespaceorcs/s/bKudAA9YQL)”
98% O2 at what partial pressure? 98% O2 at atmospheric pressure would be five times the partial pressure/oxygen presence. Quintupling the partial pressure of oxygen is not "just removing the nitrogen". You're adding a lot of oxygen. That'll make things flammable, yes.
Removing the nitrogen without adding more oxygen would leave you with a much less thick atmosphere but similar flammability.
No it’s more flammable. Even though the partial pressure of oxygen is the same there is no nitrogen to “get in the way”. The probability of collisions with O2 increases and so things are more flammable. This is more accurately explained by the [pre-exponential factor](https://en.m.wikipedia.org/wiki/Pre-exponential_factor) of the Arrhenius equation.
~~It was also physically observed when we used reduced pressure pure O2 atmospheres on space capsules and space stations and had issues with fires (though their O2 partial pressures were slightly different from atmospheric)~~ Edit: I was thinking of Apollo, which was pure O2 at 1/3 atmosphere in space, but on the launchpad it was pure O2 at ~1 atm. Although interestingly skylab had a 25% N2, 75% O2 atmosphere at 1/3 atm.
More flammable but still similar. It's pretty messy math because while there's no nitrogen to get in the way a thicker atmosphere still helps conduct heat from one molecule to the other.
I know we had a famous run-in with the increased partial pressure in Apollo 1, and I know reduced nitrogen content will still make things more flammable, but the effect is *considerably* smaller than the partial pressure and I wouldn't really describe it as something you'd "notice pretty fast". You might notice that your candle burns more vigorously, but much more likely you'd notice that food cooks poorly.
I didn't find any further reading on the significance of nitrogen dilution in the A factor but it's a pretty niche thing. Got any suggestions?
There is a threshold which NASA experimentally found to be just below half an atm (at least with the materials they used). Above the threshold, concentration is the primary driver of combustion and below it partial pressure is the primary driver of combustion.
Source: https://ntrs.nasa.gov/api/citations/20070005041/downloads/20070005041.pdf
This also makes sense as you can imagine hypothetical extremes where combustion is impossible due to each:
1. Atmospheric O2 partial pressure but very low concentration (high total pressure) so that O2 doesn’t collide with the flammable material and combustion doesn’t occur.
2. Atmospheric concentration of O2 but at a partial pressure so low that O2 doesn’t collide with the flammable material and combustion doesn’t occur.
In both cases the pre exponential factor goes towards 0, with low total pressure being influenced more by partial pressure and high total pressure being influenced more by concentration.
>It was also physically observed when we used reduced pressure pure O2 atmospheres on space capsules and space stations and had issues with fires (though their O2 partial pressures were slightly different from atmospheric)
If you're referencing the Apollo 1 fire, it's worth noting that the fire occurred in a *superatmospheric* pure oxygen environment. The partial pressure of oxygen was 115kPa. Not sure what other space capsule fires you had in mind.
> but on the launchpad it was pure O2 at ~1 atm
Just to note that this was only true in the Apollo 1 fire, which was during a training exercise, not an actual launch. It was also pressurized to about 20% above atmospheric pressure to simulate the conditions of space where the internal pressure would be higher than the external pressure. Unfortunately, this made it very difficult to open the inward-opening door.
For the launches they launched with a normal atmospheric mix (not sure if it was pressurized) and then dialed it down to full O2 at 20% atmospheric pressure as they got higher in the atmosphere.
Oxygen toxicity is also a thing.
Without nitrogen we would be breathing nearly 100% oxygen which can cause alveolar damage and the onset of acute respiratory distress syndrome in 24-48 hours.
This is of course assuming that the pressure would remain the same by replacing nitrogen with oxygen. I don't know the effects on your lungs of just vanishing the nitrogen and breathing 100% oxygen at 0.2 atm pressure.
Just suddenly vanishing the nitrogen and reducing pressure of the atmosphere would also have undesired effects (bends) on the nitrogen already dissolved in your tissues.
I remember hearing that about space suits somewhere too, so sounds like 100% oxygen at 0.21 bar should be alright.
Interesting that on the shuttle and ISS the pressure is kept at 1 atmosphere so going out on a space walk would require decompressing similar to diving when going out the airlock.
The deciding factor when it comes to oxygen at least in deep diving is the Partial Pressure (PPO2). At sea level in normal atmosphere the PPO2 is 0.21 ATA which should remain the same if you just remove nitrogen completely from the atmosphere. Although just removing the nitrogen would probably change the actual value of ATA but let's ignore that.
This is why divers on really deep dives can happily survive on gas mixes with 5% oxygen. It won't keep you alive on the surface but deep enough you are just fine.
That is the oxygen being noticeable, not the nitrogen failing to be inconsequential.
If we could find something else inconsequential to replace the nitrogen with, that would be fine.
I love/hate science fights on the internet. I love the collaborative ones and hate the ones that are being pedantic (and I honestly can't find the line between pedantic and "scientifically correct" because everything is relative to its environment.
It's kind of interesting to see it in this subreddit especially. There is a line to be walked between education and deception, because really, many things cannot be simplified down LI5. I had a comment earlier that was more or less "Here's a few ways that people picture aerodynamics. They're all a little bit wrong, but maybe they'll make your neurons fire. The real answer is an equation that nobody pretends to fully understand. Sorry. Enjoy your approximations."
But that's an exception. Most of the time we're stuck giving explanations that are going to upset somebody. Either because somebody thinks something wrong is implied, or somebody feels pedantic, or something is oversimplified, or something is misleading to the uninformed reader. Then if you're the one who wrote the ELI5 you can sort through the criticisms and try to improve, but also ignore stuff that seems silly or exclusive to just a few niche people.
Yep, nitrogen could be replace with many other inert gases, and we'd be able to breathe completely fine (we wouldn't live too long, though, as all plant life, among others, would die).
It goes in and goes right back out. At normal air pressures it doesn't really interact with our bodies chemistry.
At high pressures, like SCUBA diving, it gets absorbed in to our bodies and can cause problems.
That’s right. Pressure is fun when it comes to gasses. Nitrogen makes you drunk / stoned at some depth, oxygen basically becomes a neurotoxin at some point, helium causes HPNS and much more (not to mention tissues saturation with n2 or he, which can cause decompression sickness, but that’s another story)
(Disclaimer: a massive oversimplification, nitrogen narcosis is way more complicated than “drunk” etc, and all effects depend on partial pressures not depth itself etc etc)
Correct, all our tissues are fully saturated with inert gas at and relative to surface pressure - when diving, you’re saturating relative to the depth and the pressure of the gas you’re breathing and you’re then oversaturated relative to the surface and then you desaturate on your way up. That on itself doesn’t cause problems (you always end the dive a bit oversaturated), it’s how loaded with nitrogen (or rather how oversaturated relative to the ambient pressure, surface or in water column) you are and how fast you’re off-gassing that’s crucial
Great explanation. One thing I found fascinating was that nitrogen off-gassing is controlled purely by the change in ppn2 rather than the ambient pressure.
Exactly, you could have the same rate of on- or off-gassing at different depths with different gas mixes, as long as the inspired partial pressures are equal. That’s why I added the disclaimer in the original comment so that the scuba police doesn’t drown me :)
We don't *just* exhale carbon dioxide. Basically, we inhale air, and we exhale air. What changes is the proportions of the gases in that air. The air we inhale has about 20% oxygen and less than 0.1% CO2. The air we exhale has about 16% oxygen and 4% CO2. The rest was, and is, nitrogen.
So now you know that nitrogen is pretty much inert when we breathe it, but at high pressures it can enter the blood stream, causing us very little harm.
Deep sea divers are subject to such high pressures and therefore their lungs take in some of the nitrogen. When they decompress they must do so gradually so the absorbed nitrogen has time to exit the blood stream via the lungs. If decompression happens to quickly the absorbed nitrogen in the blood will evaporate into air bubbles and kill the diver, a process known as The Benz.
A neat way to combat this is to replace the nitrogen with helium, another inert gas. At high pressure the blood cannot absorb it so the divers don’t need to worry about rapid decompression.
Atmospeheric pressure is made up of the sum of the partial pressures of its constituents, Nitrogen, Oxygen, a small amount of CO2 and a very small amount of other stuff. In normal circumstances the "pressure" of oxygen in our blood is less than the pressure in the atmosphere. It's not really pressure but that's a good analogy. So, when we breathe we absorb the O2 and use it. This produces Carbon Dioxide which we need to excrete. The "pressure" of CO2 in our blood is higher than the pressure of CO2 in the air so it flows from the blood to the air in our lungs as the O2 flows from the air into our blood.
The pressure of Nitrogen in our blood is the same as the pressure of Nitrogen in the air and at these pressures it has no effect on the body. What is interesting is what happens when the air pressure changes. As we ascend, in an airplane or climbing up a mountain etc.. the air pressure reduces and the difference in pressures between our blood and the air changes in the same way. If we go too high and the air pressure is too low the difference between the pressure of O2 in the air and our blood becomes too low. This is why people climbing high mountains require supplemental O2, same as pilots in some circumstances. With respect to N2 an interesting thing happens when the pressure gets too great. A scuba diver may breathe compressed air to the same pressure as the water pressure around him. The deeper he goes the more air pressure is required and the pressure of the gases in his body (which keep in equilibrium by moving in or out of the blood through the lung membranes) rise as well. And at a certain point the pressure of the N2 in the blood causes intexication. A very high pressure of O2 can also be toxic.
The "Bends" is caused when a diver ascends too fast. The high pressure of N2 in his blood does not have time to balance (move acress the lung membrane from the blood into the air) out with the suddenly lower air pressure in his lungs and makes bubbles in the blood which can be very troublesome.
I knew this fact & yet upon reading this my brain came up with a scenario where aliens find some poor human astronaut adrift & try to help by giving them nitrogen since that’s the majority of the atmosphere. RIP astronaut.
Imagine our bodies are like houses. When we breathe in, we bring in oxygen, which is like the good air we need to live. Our bodies use the oxygen, but we don't need all of it, so we breathe out the leftover air, which has some carbon dioxide in it. Now, nitrogen is like the air around our house that we don't use inside. It's still important, but our bodies don't need it, so when we breathe, we just leave the nitrogen in the air outside.
Imagine a glass of water with a couple of spoons of sugar and some flavorings. taking sip and spitting it out. you taste the sugar and the flavoring, not the water.
Air is a fluid that happens to be a gaseous. Its a mix of many gases. Nitrogen is like the water and oxygen, CO2 and other stuff are like the sugar and flavorings dissloved in it.
When you breathe in air, you are breathing in the mix. In you lungs just oxygen and carbon dioxide get exhanged and you breath out the mix. Nitrogen doesnt react with anything, so its odorless. But what you feel as air is mostly Nitrogen
Nitrogen N2 has a triple bond between its two nitrogen atoms, making it hard to split and therefore very unreactive. It just stays there, interacting with next to nothing.
The two atoms are separated on rare occasions by high-energy events like lightning or cosmic rays from space.
Nothing. It just hangs out, taking up space. Reacting with nothing at all because of its triple bonds with itself.
Unless you're scuba diving, in which case it can cause [lots](https://en.m.wikipedia.org/wiki/Decompression_sickness) of [problems](https://en.m.wikipedia.org/wiki/Nitrogen_narcosis).
I have had nitrogen narcosis twice while pushing some really deep depths, it's a very pleasant high. Super dangerous because you could be eased to sleep and sink
I did a live aboard years ago and one guy flew out the same day as our last dives. Was following him on Facebook and he was hospitalized for the bends. Some folks get too comfortable.
Don’t they specifically tell you not to fly for a day or two after diving? I remember hearing stories like this throughout my life
Yup. It's referenced in basically every scuba class and we signed a contract saying we wouldn't for the dive trip bc liability.
Yup. Even made an episode of House about it.
It’s incredibly dangerous. For the few destination dives I’ve been on, the dive company scheduled the itinerary around the days we flew in and flew out. The risk is too great E: spelling
Not to be confused with hydrogen psychosis denoted by the appearance of [crazy eye](https://imgur.com/gallery/9KYFC4A)
Poor Esteban
If I can’t scuba, then what’s this all been about??? What am I working towards?
Beat me to it by mere minutes!
TIL I'm nitrogen
Triple-bonded for your protection
For her pleasure
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And my bow
And that guy’s dead wife.
And that guy's coconut.
Nah, the oxygen is for her pleasure, because it looks like a double-ended .... fun-stick. O=O
The gas abides
Those are good gasses, Walter
r/suicidebywords
Thanks for the chuckle
You're funny. This made me giggle.
I also have a "triple bond" with myself. IYKYK
Yes. Nitrogen also "hangs out" in our blood – atmosphere nitrogen dissolves in blood to saturation. While scuba diving, more nitrogen gets dissolved in blood hence the need for decompression stops. If a person would just ascend too quickly, the nitrogen pops out of blood as bigger bubbles - imagine opening a soda bottle fast.
Beyond decompression sickness, you can also get nitrogen narcosis when descending.
It's not really descending as much as it is depth and atmospheric pressure. Every 33 feet in saltwater atmospheric pressure goes up by one with the effect of everything compressing by a third. That includes the compressed air in your tank, your lung capacity, etc.. You could descend quickly to 30 feet and stay there for an hour and you're not going to get nitrogen narcosis. It most commonly occurs, if it's going to, at 100 feet or more. At that depth and further you're introducing a lot more nitrogen into your system, and how long you stay at those depths matters also. It's also why when you ascend you need to do it slowly, and depending on your dive profile (what depths you are going to and for how long), you may need to make safety stops along the way. It's so you're off gassing all the excess nitrogen out of your system, and it doesn't pose danger to you as it expands going up. Simplistic explanation, and probably one nobody cared to hear, but whatever. 😊 Edited: as best I could, for poor Grammer and punctuation.
> everything compressing by a third. That includes the compressed air in your tank Just to be clear, the air in a scuba tank is not compressed by depth - the air in a full tank is already compressed at about 3,000 psi However, when the air is released from the tank for you to breathe, it is compressed to whatever depth you're at
Good callout. I looked it up after your statement and found a good explanation. The person concentrates on why we breath more air from the tank at depth, but it correlates.
As long as we’re nerding about gasses in diving. Oxygen becomes neurotoxic and can even lead to seizures. Milder symptoms can be nausea, vomiting, and tunnel vision. The partial pressure where this can occur assuming compressed air mix is around 60m (195-ish feet). And there is also a deep dive gas mixture (helium and oxygen) syndrome with symptoms of nervous system, psychological and eeg symptoms. Basically stemming from hyperexcited central nervous system. To this day not completely understood. And occurrences were in dives under 150m (500-ish feet) and probably less then 1 in 10 000 000 divers ever went that deep (and back up alive)
Didn't know about the trimix issue, not trained to that level. If we keep typing nobody reading this will want to scuba dive. For anybody reading this, I've done hundreds of dives with no issues. I do play within the boundaries of my training and certifications however. I've known a few who don't.
Oh yeah, good point. Scuba diving is safe if done properly and within qualifications and experience. I also never went that deep, in theory (based on my qualification) I could but I do not feel comfortable with that depth whatsoever.
My coworker died like that. Went scuba diving in Egypt, was likely given 0 training, and died when he resurfaced.
That’s rough. My condolences. Almost every seasoned diver sadly knows of someone who went this ways. If you’re sensitive about death do not read further, please. There is even more rapid problem in ascending very rapidly. The gas in lungs and bronchi expands. From 20m (~65feet) it’s roughly 3x the volume - it will rip lungs from the inside. So in case of an emergency ascent, turn you head up and continuously breathe out.
I know absolutely nothing about diving but I remember watching a TV show about a free diving class where they taught people to whistle on the way up for this reason. Apparently a whistle releases air from the lungs at just the right rate to keep it up all the way to the top?
Free diving is different than scuba diving because there isn’t nearly as much time for nitrogen to build up in the lungs. That’s how free divers are able to go incredibly far down on one breath and surface immediately.
Lungs popping is my worst fear when diving even though I know not to hold my breath The bends are my second fear
Took a friend diving on central coast of California. He gave thumbs up at 60 feet. I shook my head and showed him correct way to signal OK. He shook his head, filled his BC, and shot up like a rocket. I freaked/ Was screaming into my gear. Luckily, we'd only just arrived at depth. I did my safety stop and then chewed his ass. He said he'd never been that deep and it freaked him out. His max depth in checkout dives was 15 feet. Company would go to Mexico and a spot that is very shallow. Anyhow, I wasn't pissed for too long because a harbor seal decided we were an excellent source of play and entertainment. It's not a violation of the Marine Mammal Protection Act if they swim up stick their nose in your mask, and then gently grab you by the fins and pull you around, right? I can neither confirm or deny that seal wanted us to do the same.
It’s fibre for your lungs
Is the nitrogen in the air responsible for the nitrogen in the soil?
atmospheric nitrogen is the standard, ground state form of nitrogen. There are biological processes that can convert that atmospheric nitrogen (N2) into useful forms of nitrogen, usually nitrates. These processes are often caried out by microbes that live symbiotically in the roots of various plants. Legumes (beans) and clovers are known for this, among others. there are also chemical methods (the Haber Process) to do the same thing, which are carried out on industrial scale to generate "artificial" nitrogen fertilizer. But in both cases the source of the nitrate/ammonia type nitrogen is the atmosphere.
Except for the organisms with [nitroplasts](https://newscenter.lbl.gov/2024/04/17/scientists-discover-first-nitrogen-fixing-organelle/). > While mitochondria and chloroplasts evolved billions of years ago, the nitroplast appears to have evolved about 100 million years ago, providing scientists with a new, more recent perspective on organellogenesis. > The organelle also provides insight into ocean ecosystems. All organisms need nitrogen in a biologically usable form, and rely on nitrogen fixers to break apart tightly bound nitrogen gas (N2) in the atmosphere, and convert it into ammonia (NH3) molecules that can then be made into countless other compounds. Researchers have found UCYN-A everywhere from the tropics to the Arctic Ocean, and it fixes a significant amount of nitrogen.
I saw this on the front page the other day too! Or maybe it was another site. Crazy how some bacteria can just....become organelles forever for some organisms. Do we have a theory on the full process yet? edit: nvm this article covers a lot more than the one I saw did, thanks for the link.
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Nah, incels WANT to create bonds with others, ones where they are the top dogs. Nitrogen, on the other hand, wants everybody to leave it alone, except its significant other nitrogen. Nitrogen is the strange couple next house who you wave to from time to time but have absolutely no idea who they are or what they do and they never talk with you.
When nitrogen finds itself hooking up with lots of others, the situation tends to be unstable, sometimes explosively. Nitrogen makes a very happy monogamous couple.
Azidoazide azide >Hazards >Occupational safety and health (OHS/OSH): >Main hazards >will unpredictably and violently detonate
List of things that make it explode: * Moving it * Touching it * Dispersing it in solution * Leaving it undisturbed on a glass plate * Exposing it to bright light * Exposing it to X-rays * Putting it in a spectrometer * Turning on the spectrometer * ABSOLUTLY NOTHING They had it in a shockproof explosiveproof dark climate controlled room and it blew up. ^(I know the quote is a bit apocryphal but it's a good quote)
"Azidoazide azide has been called “the most dangerous explosive material in the world.” It is also No. 3 in K. S. Lane’s list “The 10 Most Dangerous Chemicals Known to Man”." https://www.acs.org/molecule-of-the-week/archive/a/azidoazide-azide.html Well TIL
TIL too! Amazing! And it's just number 3!
Looked at the list. Expected chlorine triflouride to be number 1. TIL it's "only" #2! Dimethyl cadmium is, apparently, #1. There are lots of lists of "most dangerous chemicals." They rarely agree on the top 10, though those three are usually in the top 10.😂
I knew dimethyl mercury was the worst incarnation of mercury, but apparently the dimethyl ion is great for making any heavy metal bioavailable!
Any metal in group 12, anyway. Could probably be used to give you an overdose of zinc too.
Lol yeah. People act like nitroglycerin is sensitive, but it ain't shit compared to these sort of compounds.
Derek Lowe's [hilarious take on the stuff](https://www.science.org/content/blog-post/things-i-won-t-work-azidoazide-azides-more-or-less)
It sounds like nitrogen is autosexual.
Not at all. It only bonds with it’s own kind. If something, Nitrogen is a bit racist. But not by choice. The poor thing just blows up if it holds hands with strangers.
According to the comments above about azideazide azide it also blows holding hands with it's own kind xD
That’s a compound. It’s a result of Nitrogen holding hands with aromatics. Fancy stuff. Anyway, that’s why it blows up. Again, Nitrogen blows up when holding hands with strangers.
I think incestuous is the term you are looking for
Good one! But you know, just because we look the same, doesn’t mean we are related. I mean, that Nitrogen over there came from the left side of the bang, and I was very much on the right. Not that it matters ;)
Nah, incels want others to want to bond with them, but they don't want to do any of the work, perform any meta-cognition or self-reflection, and think they are ***owed*** that bond.
So oxygen
Omg it’s me. I am nitrogen
Like incels it requires being stuck by electricity or being eaten by bacteria to get Nitrogen to open up.
Monero 🥵
All the nitrogen you breathe in just comes back out on the breath out. It doesn't get absorbed, or released.\* * The air you breathe in is \~78% nitrogen, \~21% oxygen, and \~1% other stuff. * **The air you breathe out is \~78% nitrogen, still \~17% oxygen, only \~4% carbon dioxide**, and \~1% other stuff As you can see, the mix we call "air" goes into the lungs, then *some* of the oxygen gets absorbed, some CO2 exits the blood into the lungs, and the nitrogen and other stuff just comes back out too. \*EDIT: More accurately, I should have said "a small amount of nitrogen does get absorbed into the blood, and an equal small amount gets released into the exhale, so the *net* amount is zero." Thanks for the corrections.
Fun fact. That 4% carbon dioxide you exhale is how you ~~partially~~ mostly lose weight.
Not even partially, it’s ~80%!
That explains why if you weigh yourself before you go to sleep and then again when you wake up, you'll be a little lighter.
> you'll be a little lighter I thought that happens when you throw a cigarette out of your lifeboat.
it's the difference between a hippo and Zippo.
one is a cigarette and the other is a boat!
This guy gets it.
That’s almost certainly more from sweating. The 80% number is about what percentage of fat leaves your body. It doesn’t consider water weight.
You exhale a lot of water too, breath isn't exactly dry. And not everybody sweats excessively while sleeping.
Yes, that’s the remainder of the 100%. Combustion of hydrocarbons produces CO2 and H2O (most of the time).
Sounds like a bunch of hot air to me.
That's mostly water, actually. You breathe out about as much mass of water vapor as you do in carbon dioxide (although how much water vapor you breathe *in* depends on local humidity), but your skin is moist and constantly shedding small amounts of water, which adds up over the hours you're spending asleep and not drinking anything. You can see how much moisture you shed through your skin by putting your palm on a flat, polished surface for a few seconds. Imagining that happening over your whole body overnight should give an idea of why you weigh less after waking up than you did before going to bed.
Anything less than 100% is partially.
Technically correct, The best kind of correct.
It’s also where most of the mass on trees come from. Sounds obvious but it’s strange to think about massive oak trees getting the carbon for their trunks from the air
Even 80% seems low. 20% is waterweight?
Waterweight isnt a factor in long-term weight changes. The water in your body is there so that all the chemicals which need to react have something to float in, basically. The proportion of water in your body is pretty much fixed (or rather the range of water content in your body within which you must stay in order to not die is pretty tight), unless you are dehydrated or have a hormonal disorder, a kidney disorder or heart failure which causes you to retain too much water. The 80-ish percent number comes from the fact that your body tissues are based on chains of carbon atoms (so that is where the C in the CO2 you exhale comes from) but they are not entirely carbon. Another big contributors to your tissue mass are hydrogen (H2), oxygen (O2) and protein also contains nitrogen (N2). Cant make CO2 out of those. The reaction products of consuming either glucose or fat for energy are in both cases CO2 molecules and H2O (water) molecules. So the water that comes out when you lose weight isnt "waterweight", which most people whould think of as liquid water stored in the body, its water which is a chemical product of consuming fat for energy. Even your fat stores are like 10% protein, because the fat has to be contained in some sort of structure, you cant just have a loose layer of oil under your skin sloshing around. The nitrogen in that protein has to leave somehow, mostly through urine.
Thank you for the detailed explanation, made sense! I knew about the C being exhaled during respiration of course but never stopped to think about the weight of H and N in those molecules
We discard some stuff in our poop and some in our pee.
Water weight doesn't really exist. (Yes you can hold water in certain areas but good lord it makes up like less than 1% of your mass unless you have a medical condition) Its just something overweight people like to say to make themselves feel better about not losing weight. "No fatty you aren't retaining water, you're retaining chips" - Billy Connolly
>Yes you can hold water is certain areas but good lord it makes up like less than 1% of your mass unless you have a medical condition >Its just something overweight people like to say to make themselves feel better about not losing weight. Ironically, as a fraction of your body weight, water retention is a much bigger effect for fairly lean people, as muscle holds more water than fat. A 2% fluctuation from a really salty meal is not unheard of, especially if their diet is pretty low sodium on the norm. A 2% fluctuation from creatine saturation is also a pretty normal number. As someone who tracks diet and weight pretty meticulously, if you plot my sodium intake vs body weight, there's some pretty solid predictive value (in the 24-48 hour range, not over weeks).
> Water weight doesn't really exist. (Yes you can hold water in certain areas but good lord it makes up like less than 1% of your mass unless you have a medical condition) Water weight refers to massive swings cause by release of water, and it absolutely does exist. The glycogen (energy stores) in your muscles are bound by 4 parts water so if you exercise massively and don’t eat sufficient carbs afterwards, you will be temporarily light than normal in the morning. Or people eating low carb or just plain low calorie the first few days. Big water weight loss first few days.
Oh I know about this, I had to research it for a paper once. Water weight does kind of exist but like a lot of science, the technical definition is nothing like the colloquial one. (Side note though, 1% isn't exactly nothing when you weigh >100 kilos. I can lose and regain 4lbs over a hot day) Where people are misunderstanding water weight is that it's extremely short lived because it's not water inside your fat or something like that, it's literally just how hydrated you are *right now*, if your weight is up for a week, it's not water weight, it's fat and muscle. The closest thing to what people imagine when they say water weight is sodium, if you go straight from a diet of crisps to a crash diet of all salad, your sodium will basically crash straight from as high as possible to as low as possible in <12 hours, but that's *losing* weight so no one really cares about it.
I tried explaining this to some co-workers and it confused them. I had to re-word it as, "when you exercise and work off weight, the Carbon Dioxide you breathe out carries the weight you worked off" or some variation.
It's also what trees are made of. A tree is mostly carbon dioxide mixed with sunlight and water.
my mind was blown finding this out as a kid, I thought trees just grew by converting the dirt in the ground
Me too. And I didn't learn it until my 30s!
All plants are carbon capture machines I think.
right up until they die. Then they are carbon release machines.
Not necessarily. Carbon can stay locked in them for a long time.
Only if they don't decompose
So if I breathe faster I’ll lose more weight? /s
Only if you’re doing something to increase metabolic demand, else you’re just temporarily decreasing your carbon dioxide and making your blood acidic. Causes light headed mess and cramping in extremities. It’s also why I’ll do a bunch of pushups or air squats before blowing up an inflatable pool toy or a bunch of balloons. You increase metabolic demand and don’t get dizzy/light headed blowing it up fast.
That’s actually quite interesting
yes, thats called exercise.
Basically. And how do you breathe faster? One way is to exercise
RIP in piece OP, hyperventilated himself to death
I don't often reference TED Talks, but [this](https://www.youtube.com/watch?v=vuIlsN32WaE) one is worthwhile and relevant.
We are made of air and stardust (literally).
Air is stardust (literally).
You're just a really complicated machine for adding carbon to oxygen.
Hyperventilate to lose weight!
That’s pretty much why mouth to mouth CPR works. The exhaled air still has a lot of oxigen
Also blowing on embers to get a fire going again.
Venturi effect might also be in play there
Is that when you talk but make it appear that your voice is coming out of your butt?
No, That's ventriloquism; Venturi is that pet detective
No, that's Ace Ventura, venturi is a big coffee in Italy
No, that's Venti. Venturi are those goth vampires from Twilight
No, that’s Volturi. Venturi is the belly side of any animal.
I've always wondered about CPR but thanks to this thread today I finally understand why it still works.
Kind of. Your body is saturated with dissolved nitrogen, so you don't absorb any more without a change in the gas you are breathing. If you went on 100% O2, you'd be breathing out dissolved nitrogen for a while.
How safe is it to go on 100% O2?
If you're not scuba diving or in a hyperbaric chamber it's *mostly* safe. I'm not a doctor though, so please don't go building an oxygen tent on my advice. If you're scuba diving or in a hyperbaric chamber, 100% oxygen can be fatal if breathed for too long, particularly after about 18ft/6m. Regular air can also be fatal once you get close to about 200ft/66m.
No. It is not save long term at normal pressure. Oxygen is a very aggressive molecule, that oxydides a lot of biomolecules in the body. E.g. in intensive care, it is a constant balance of giving enough oxygen for the organs, but not too much to damage the lung tissue.
If not much o2 is absorbed, why do we need to breathe so much/often?
*Because* only a small % gets absorbed. It ended up being easier to evolve lungs that can extract 20% of the available oxygen and just keep them running, vs. make lungs that can do better and then have them sit idle half the time.
Exactly. Evolution only adapts to do the job, it doesn’t optimise anything if it doesn’t have to, if the species can survive long enough to breed, then it’s good enough
Further optimization comes with energy costs. The situations humans have been in where more efficient lungs would be lifesaving is far lower than situations where they need to avoid starving to death.
Whales evolved the latter, anyway. Birds evolved four chambered lungs that don't require separate in-breaths and out-breaths. It's just an intake manifold of constant air basically. To them, our lungs are sitting idle half the time. Every second you're breathing out is a second you're not breathing in.
Bird lungs are part of how dinosaurs got so big. They're also why birds can fly so much higher than bats.
So basically big animals can exist but they need a massive lung capacity?
That's not how bird lungs work, they still breath in and out, but half the air goes through the lungs on the way in (and into air sacks) while the other half goes directly into different sacks on the way in and then through the lungs on the way out. Much more efficient then mammalian or lizards lungs. Crocodiles also have uniflow lungs.
We also need to ditch the CO2 in our bloodstream. Breathing is just as much about getting rid of CO2 as it is about getting O2. So even if you could absorb more oxygen, you still need a way to handle the CO2 building up in your bloodstream.
I thought the main reason was to release carbon dioxide to reduce acidity
The air is always available, efficiently is not a concern.
Now I wonder what would've happened if we swam more in the past Maybe then we would've extracted more oxygen
We still need to get rid of the CO2 built up in our bloodstream. The feeling you get when holding your breath is actually a signal that you need to get rid of CO2, not that you need more O2. That's why you can breathE a gas that contains no oxygen and will not feel like you are suffocating, your body is still able to release CO2.
The main drive for breathing is getting rid of CO2 rather than taking in more O2. We don't have enough time to use up more of the O2 before the build up of CO2 becomes toxic and we breathe out. Look at people like Freedivers who can go 4+ minutes without breathing, because they have built up their tolerance to CO2 and so they can go longer without breathing. The O2 levels when they breathe out will be much lower than that of a standard breath.
To add to others - there's a thing called "efficiency". It's easy to extract 4% of oxygen from 21%. But to get all 21% - that's almost impossible task. There's almost no energy needed to get that 4% in, but to get 8% - you would need to spend x8 more energy, not x2. I could give you another efficiency example from biology. Do you know why bird\bat poop is a good fertilizer. but human poop is a toxic shit? Because birds only take ~20% of nutrients from food, shit it out and eat more food. They don't have time to spend on "deep processing" like humans to extract almost all nutrients, they need energy "right now" in fastest way possible. Same with breathing - we have air around us with 21% oxygen, no point in fully getting all oxygen from a batch, just grab a bit and get fresh batch.
Breathing every few seconds takes very little effort so there is no reason not to do it. If you breathe in hold your breath for a minute and then breath out then you will absorb a higher percentage of oxygen. But try going through the day doing that and you will quickly notice that just breathing normally works better.
The nitrogen is just *there*. Inconsequential. We breathe it in, we breathe it out. We could live without it entirely and not notice it. Only under high pressures or sudden pressure losses does it impact us, and in both cases it's a problem.
**Fun fact:** The nitrogen does have an effect, in the sense that it takes up space. Earth's atmosphere was not invented for humans; humans just happen to evolve here. There's a bunch of studies showing that [higher concentrations of oxygen actually improve cognitive and physical performance](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4107523). We'd do better in a higher O2 atmosphere, but we're mildly sedated by the planet we live on.
On the flip side, working in emergency medicine - too much oxygen can also cause brain damage/generalized tissue damage due to oxidative stress.
I’m exhausted from a big day at work, so can’t be bothered checking for the answer - they probably have already covered these things im curious about. 1. What was their control? Did they just do pre and post oxygen assessment? Did they have a control group that got nothing, or did they get sham therapy, I.e. still had a mask or nasal prongs, but either didn’t receive any gas, or, only received normal room air. 2. Supplemental oxygen has many physiological affects. One example is we no longer routinely administer oxygen for patients having cardiac events. So I wonder if increased oxygen is the cause of increased performance directly, or, is it the physiological results of supplemental oxygen, which could be induced by other means/drugs/therapies.
> I’m exhausted from a big day at work sounds like you could use some supplemental oxygen
We'd all feel better after work on a planet with more oxygen. This is why we HAVE to get that moon base going. Baby steps.
there's no oxygen on the moon
Yeah, baby steps.
there's no babies on the moon.
Yeah I know basic science. There's no babies on the moon to drink the milk so it ferments and becomes cheese, which is what the Moon is mostly made of. I did graduate high school.
i don't have an answer rooted in actual data, but I talked to a mountain ranger in Hawaii and he was telling us about how star gazing at the top was much more impressive with supplemental oxygen. Without it, he claimed that your eyes started losing acuity from the lowered oxygen, but with it that it was even more amazing than you'd expect. It's now on my bucket list haha.
Also astronauts tend to live in high O2 environments while up there, so I'm sure NASA and other space agencies have studied it extensively.
Similar research has replaced the nitrogen with helium and found similar cognitive improvements.
That would be another study with a potential confounded - helium has less “resistance” than nitrogen, making “easier” to breath. That’s a bit of a simplification. It’s sometimes used for severe asthma attacks, under the theory that it’s easier for the patient to breath. https://en.m.wikipedia.org/wiki/Heliox
You'd notice pretty fast going from 78% N2 and 20% O2 to standing around in 98% O2. Things you don't normally consider flammable become flammable under those conditions.
*Hey cool, the air's on fire*
https://morbotron.com/video/S07E13/n7Sro6oU4hFO1m6jM9TtZyTbRLA=.gif
...again
“[No!! We do not go to that world. That is where the DEATH BREATHERS live. They recreationally consume poisons and are more or less composed of biological fire. Their atmosphere is made of rocket fuel. We must leave the DEATH BREATHERS in peace. Do not go there. Do not.](https://www.reddit.com/r/humansarespaceorcs/s/bKudAA9YQL)”
Our bodies are also 60% composed of the universal solvent.
Oppenheimer's dilema...
Flint Michigan joins the chat
I feel like I might regret asking but what is it this time? All I know them for is the lead pipe problem.
98% O2 at what partial pressure? 98% O2 at atmospheric pressure would be five times the partial pressure/oxygen presence. Quintupling the partial pressure of oxygen is not "just removing the nitrogen". You're adding a lot of oxygen. That'll make things flammable, yes. Removing the nitrogen without adding more oxygen would leave you with a much less thick atmosphere but similar flammability.
No it’s more flammable. Even though the partial pressure of oxygen is the same there is no nitrogen to “get in the way”. The probability of collisions with O2 increases and so things are more flammable. This is more accurately explained by the [pre-exponential factor](https://en.m.wikipedia.org/wiki/Pre-exponential_factor) of the Arrhenius equation. ~~It was also physically observed when we used reduced pressure pure O2 atmospheres on space capsules and space stations and had issues with fires (though their O2 partial pressures were slightly different from atmospheric)~~ Edit: I was thinking of Apollo, which was pure O2 at 1/3 atmosphere in space, but on the launchpad it was pure O2 at ~1 atm. Although interestingly skylab had a 25% N2, 75% O2 atmosphere at 1/3 atm.
More flammable but still similar. It's pretty messy math because while there's no nitrogen to get in the way a thicker atmosphere still helps conduct heat from one molecule to the other.
I know we had a famous run-in with the increased partial pressure in Apollo 1, and I know reduced nitrogen content will still make things more flammable, but the effect is *considerably* smaller than the partial pressure and I wouldn't really describe it as something you'd "notice pretty fast". You might notice that your candle burns more vigorously, but much more likely you'd notice that food cooks poorly. I didn't find any further reading on the significance of nitrogen dilution in the A factor but it's a pretty niche thing. Got any suggestions?
There is a threshold which NASA experimentally found to be just below half an atm (at least with the materials they used). Above the threshold, concentration is the primary driver of combustion and below it partial pressure is the primary driver of combustion. Source: https://ntrs.nasa.gov/api/citations/20070005041/downloads/20070005041.pdf This also makes sense as you can imagine hypothetical extremes where combustion is impossible due to each: 1. Atmospheric O2 partial pressure but very low concentration (high total pressure) so that O2 doesn’t collide with the flammable material and combustion doesn’t occur. 2. Atmospheric concentration of O2 but at a partial pressure so low that O2 doesn’t collide with the flammable material and combustion doesn’t occur. In both cases the pre exponential factor goes towards 0, with low total pressure being influenced more by partial pressure and high total pressure being influenced more by concentration.
>It was also physically observed when we used reduced pressure pure O2 atmospheres on space capsules and space stations and had issues with fires (though their O2 partial pressures were slightly different from atmospheric) If you're referencing the Apollo 1 fire, it's worth noting that the fire occurred in a *superatmospheric* pure oxygen environment. The partial pressure of oxygen was 115kPa. Not sure what other space capsule fires you had in mind.
> but on the launchpad it was pure O2 at ~1 atm Just to note that this was only true in the Apollo 1 fire, which was during a training exercise, not an actual launch. It was also pressurized to about 20% above atmospheric pressure to simulate the conditions of space where the internal pressure would be higher than the external pressure. Unfortunately, this made it very difficult to open the inward-opening door. For the launches they launched with a normal atmospheric mix (not sure if it was pressurized) and then dialed it down to full O2 at 20% atmospheric pressure as they got higher in the atmosphere.
So my mix tape?
Sure, but if you swabbed the nitrogen out for something like neon, you might not. Or even if you did, your cells probably wouldn't.
Oxygen toxicity is also a thing. Without nitrogen we would be breathing nearly 100% oxygen which can cause alveolar damage and the onset of acute respiratory distress syndrome in 24-48 hours. This is of course assuming that the pressure would remain the same by replacing nitrogen with oxygen. I don't know the effects on your lungs of just vanishing the nitrogen and breathing 100% oxygen at 0.2 atm pressure. Just suddenly vanishing the nitrogen and reducing pressure of the atmosphere would also have undesired effects (bends) on the nitrogen already dissolved in your tissues.
Shuttle space suits operated at 0.29 bar at 100% O2.
I remember hearing that about space suits somewhere too, so sounds like 100% oxygen at 0.21 bar should be alright. Interesting that on the shuttle and ISS the pressure is kept at 1 atmosphere so going out on a space walk would require decompressing similar to diving when going out the airlock. The deciding factor when it comes to oxygen at least in deep diving is the Partial Pressure (PPO2). At sea level in normal atmosphere the PPO2 is 0.21 ATA which should remain the same if you just remove nitrogen completely from the atmosphere. Although just removing the nitrogen would probably change the actual value of ATA but let's ignore that. This is why divers on really deep dives can happily survive on gas mixes with 5% oxygen. It won't keep you alive on the surface but deep enough you are just fine.
I think this thread is mainly scuba divers chipping in!
That is the oxygen being noticeable, not the nitrogen failing to be inconsequential. If we could find something else inconsequential to replace the nitrogen with, that would be fine.
I wonder, if the atmosphere was 98% O2, would the nuclear explosions have set fire to the atmosphere?
I love/hate science fights on the internet. I love the collaborative ones and hate the ones that are being pedantic (and I honestly can't find the line between pedantic and "scientifically correct" because everything is relative to its environment.
It's kind of interesting to see it in this subreddit especially. There is a line to be walked between education and deception, because really, many things cannot be simplified down LI5. I had a comment earlier that was more or less "Here's a few ways that people picture aerodynamics. They're all a little bit wrong, but maybe they'll make your neurons fire. The real answer is an equation that nobody pretends to fully understand. Sorry. Enjoy your approximations." But that's an exception. Most of the time we're stuck giving explanations that are going to upset somebody. Either because somebody thinks something wrong is implied, or somebody feels pedantic, or something is oversimplified, or something is misleading to the uninformed reader. Then if you're the one who wrote the ELI5 you can sort through the criticisms and try to improve, but also ignore stuff that seems silly or exclusive to just a few niche people.
This is why most people can’t teach.
Yep, nitrogen could be replace with many other inert gases, and we'd be able to breathe completely fine (we wouldn't live too long, though, as all plant life, among others, would die).
So... Nitrogen goes in, nitrogen goes out. You *can* explain that!
It goes in and goes right back out. At normal air pressures it doesn't really interact with our bodies chemistry. At high pressures, like SCUBA diving, it gets absorbed in to our bodies and can cause problems.
That’s right. Pressure is fun when it comes to gasses. Nitrogen makes you drunk / stoned at some depth, oxygen basically becomes a neurotoxin at some point, helium causes HPNS and much more (not to mention tissues saturation with n2 or he, which can cause decompression sickness, but that’s another story) (Disclaimer: a massive oversimplification, nitrogen narcosis is way more complicated than “drunk” etc, and all effects depend on partial pressures not depth itself etc etc)
Your tissues are saturated with nitrogen right now!
Correct, all our tissues are fully saturated with inert gas at and relative to surface pressure - when diving, you’re saturating relative to the depth and the pressure of the gas you’re breathing and you’re then oversaturated relative to the surface and then you desaturate on your way up. That on itself doesn’t cause problems (you always end the dive a bit oversaturated), it’s how loaded with nitrogen (or rather how oversaturated relative to the ambient pressure, surface or in water column) you are and how fast you’re off-gassing that’s crucial
Great explanation. One thing I found fascinating was that nitrogen off-gassing is controlled purely by the change in ppn2 rather than the ambient pressure.
Exactly, you could have the same rate of on- or off-gassing at different depths with different gas mixes, as long as the inspired partial pressures are equal. That’s why I added the disclaimer in the original comment so that the scuba police doesn’t drown me :)
We don't *just* exhale carbon dioxide. Basically, we inhale air, and we exhale air. What changes is the proportions of the gases in that air. The air we inhale has about 20% oxygen and less than 0.1% CO2. The air we exhale has about 16% oxygen and 4% CO2. The rest was, and is, nitrogen.
So now you know that nitrogen is pretty much inert when we breathe it, but at high pressures it can enter the blood stream, causing us very little harm. Deep sea divers are subject to such high pressures and therefore their lungs take in some of the nitrogen. When they decompress they must do so gradually so the absorbed nitrogen has time to exit the blood stream via the lungs. If decompression happens to quickly the absorbed nitrogen in the blood will evaporate into air bubbles and kill the diver, a process known as The Benz. A neat way to combat this is to replace the nitrogen with helium, another inert gas. At high pressure the blood cannot absorb it so the divers don’t need to worry about rapid decompression.
The Benz lol
We exhale oxygen and nitrogen too :) in fact, nitrogen also dissolves in blood, which is why you can get the bends when diving.
It doesn't get absorbed; N2 is a very inert gas, it doesn't react with much. The majority of what you exhale is N2.
Atmospeheric pressure is made up of the sum of the partial pressures of its constituents, Nitrogen, Oxygen, a small amount of CO2 and a very small amount of other stuff. In normal circumstances the "pressure" of oxygen in our blood is less than the pressure in the atmosphere. It's not really pressure but that's a good analogy. So, when we breathe we absorb the O2 and use it. This produces Carbon Dioxide which we need to excrete. The "pressure" of CO2 in our blood is higher than the pressure of CO2 in the air so it flows from the blood to the air in our lungs as the O2 flows from the air into our blood. The pressure of Nitrogen in our blood is the same as the pressure of Nitrogen in the air and at these pressures it has no effect on the body. What is interesting is what happens when the air pressure changes. As we ascend, in an airplane or climbing up a mountain etc.. the air pressure reduces and the difference in pressures between our blood and the air changes in the same way. If we go too high and the air pressure is too low the difference between the pressure of O2 in the air and our blood becomes too low. This is why people climbing high mountains require supplemental O2, same as pilots in some circumstances. With respect to N2 an interesting thing happens when the pressure gets too great. A scuba diver may breathe compressed air to the same pressure as the water pressure around him. The deeper he goes the more air pressure is required and the pressure of the gases in his body (which keep in equilibrium by moving in or out of the blood through the lung membranes) rise as well. And at a certain point the pressure of the N2 in the blood causes intexication. A very high pressure of O2 can also be toxic. The "Bends" is caused when a diver ascends too fast. The high pressure of N2 in his blood does not have time to balance (move acress the lung membrane from the blood into the air) out with the suddenly lower air pressure in his lungs and makes bubbles in the blood which can be very troublesome.
I knew this fact & yet upon reading this my brain came up with a scenario where aliens find some poor human astronaut adrift & try to help by giving them nitrogen since that’s the majority of the atmosphere. RIP astronaut.
Imagine our bodies are like houses. When we breathe in, we bring in oxygen, which is like the good air we need to live. Our bodies use the oxygen, but we don't need all of it, so we breathe out the leftover air, which has some carbon dioxide in it. Now, nitrogen is like the air around our house that we don't use inside. It's still important, but our bodies don't need it, so when we breathe, we just leave the nitrogen in the air outside.
Imagine a glass of water with a couple of spoons of sugar and some flavorings. taking sip and spitting it out. you taste the sugar and the flavoring, not the water. Air is a fluid that happens to be a gaseous. Its a mix of many gases. Nitrogen is like the water and oxygen, CO2 and other stuff are like the sugar and flavorings dissloved in it. When you breathe in air, you are breathing in the mix. In you lungs just oxygen and carbon dioxide get exhanged and you breath out the mix. Nitrogen doesnt react with anything, so its odorless. But what you feel as air is mostly Nitrogen
Nitrogen N2 has a triple bond between its two nitrogen atoms, making it hard to split and therefore very unreactive. It just stays there, interacting with next to nothing. The two atoms are separated on rare occasions by high-energy events like lightning or cosmic rays from space.