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60

There are three separate issues here: Too much oxygen, and the human body (as well as any other organic material) will be highly flammable. You don't really want to live there. Too high or too low oxygen partial pressure, and the metabolism won't work correctly. The other gases, or lack of them, may also cause problems So a 100% oxygen atmosphere will not ...


43

30% Oxygen levels are not a huge deal as far as respiration goes. You would perform better in endurance events as it is easier to get more oxygen into your system but your body would adapt. 100% Oxygen can be dangerous or even toxic but a relatively modest increase to 30% is unlikely to have many side effects on humans. There is going to be one large side ...


43

Titanium Immunity to Environmental Attack Architectural titanium's unsurpassed corrosion resistance results from its stable, highly-adherent, protective surface oxide film. Because the metal is highly reactive and has a strong affinity for oxygen, the beneficial oxide film forms spontaneously when exposed to moisture or air. In fact, a damaged oxide ...


43

There's evidence dinosaurs in general had the same sort of respiratory system that the modern dinosaurs have kept, which is more efficient than the system used by mammals. This is suspected to be part of the reason why they could get to such a huge size; they could more efficiently process it to extract the oxygen, and there's no reason to assume they'd have ...


35

In a word, no. Perfect seals simply do not exist in the real world. Fortunately, neither do perfect ships. Even if you had perfect seals, you wouldn't be able to cruise the skies for all eternity because you'd eventually break down as you impact small particulate matter. Entropy always wins. Fortunately, for practical purposes, you can do okay. You ...


30

To a lazy first approximation, the O2 concentration now is about 70% of what it was back then. To get a similar effective difference in the partial pressure of oxygen, you can go to an altitude of about 2900m. Without acclimatization, this can be quite unpleasant (or potentially life threatening) and physical activity can be challenging. It is possible to ...


21

100% oxygen is dangerous - stuff will burn, oxygenation can damage tissues. Apollo 1 had pure oxygen atmosphere, did not ended up well. oxygen is toxic 90% CO2 will kill you (not enough partial pressure of oxygen in hemoglobin) 2% of oxygen is not enough. 10% of oxygen with other inert gasses (nitrogen (not inert, but not reactive either), helium) might ...


19

Way, way, more than we could ever feed. First, no one has put a hard number on the number of people the Earth could support purely based on oxygen consumption. This is because we'd run into food and clean water problems long before we hit an oxygen ceiling. It was nicely put in this article about Earth's oxygen reserves: Simply put, our atmosphere is ...


19

Closed cycle life support systems (CLSS) are the only way to go for prolonged space travel or even space stations and colonies orbiting a Sun. As pointed out, the real problem is making up losses since no system is ever going to be 100% efficient. One of the key elements for any sort of CLSS needs to be water. Water is essential for the life processes of ...


18

Let's start with considering the entire mass of the atmosphere: The total mean mass of the atmosphere is $5.1480 \cdot 10^{18} kg$. We know that Oxygen accounts for 21% in volume, and considering that The density of air at sea level is about $1.2 \ kg/m^3$ We get that the "sea level" volume of the entire atmosphere is $V =$$ 5.1480 \cdot 10^{18} \...


18

You need to fundamentally abandon the idea of building a generation ship, and sending it off into deep space. A generation ship needs to be self sustaining, which includes the capability to recycle and manufacture any part of the ship several times over. This kind of manufacturing capability you most likely need anyway when you arrive at your target. The ...


17

First of all, the premise is a bit off. Something like 70% of the oxygen generation on Earth is done by plankton in the oceans, so a blight which kills land based plants will be somewhat inconvenient in terms of O2 production, the real problem in that case is people are going to get pretty hungry pretty fast with the destruction of the terrestrial food chain....


17

Alas, I couldn't find exact details of what percentage of O2 would be the limit; The best I could find for details is the chart below. I did, however, find details on what overdosing of oxygen can do. Apparently, too much oxygen intake can lead to issues with how cells can function. It leads to overproduction of something called ROS, which affects how ...


16

In short: No benefits, no short-term damages. But quite possibly adverse long-term effects. A normal person breathes about 7 1/2 to 8 liters per minute in rest and under normal conditions, containing 1.6 to 1,7 liters of oxygen. Only about 0.3 liters make it into the blood. Patients with hypoxia are often supplied with oxygen. The "standard" amount is 2 ...


16

If you mean it we lose 15% of current concentrations, to %17.85 it will be harder to breath we will have a harder time concentrating and thinking. Many more people would need to be put on Oxygen to survive, many smokers and others with lung and blood issues would likely die before they knew what was wrong. Some of it might depend on what replaces that ...


16

It depends on the atmospheric pressure. This chart from NASA shows the relationship between O2 concentration, atmospheric pressure, and how comfortable a human will be breathing that atmosphere. You could actually survive in atmosphere with 100% oxygen, just at a much lower pressure than on Earth. On this chart you can see the border for survivable O2 ...


15

The key is in the ecosystem you're taking with you. Organic tech. I contend that it's about an integrated system, not just about one aspect of that system. The floor is a Tapestry Lawn: Attribution: grassfreelawns.co.uk The various species of bee and other insect that you'll no doubt be wanting to take with you to populate your new world will love it, as ...


14

Arthropodes would evolve to become larger. In the paleozoic era, when the oxygen levels were higher than today, giant insects roamed the Earth surface. Most of the other animals and plants would evolve in response of this. Some of these evolutions would be problematic, others won't. The humans are no exception, and a race of giants may evolve. In some areas ...


14

Your problem is mass. There's a LOT of oxygen in the atmosphere. Hydrogen needed For each $O_2$ you need 4 hydrogen atoms. Our atmosphere has a mass of approximately: $5.15×10^{18} kg$ By mass 23% of that is oxygen (by volume it's 21% but we're interested in mass). That gives oxygen: $1.18*10^{18} kg$ Combining Hydrogen and Oxygen gives water. $\frac2{...


14

The most common solution to this approach is to try and mirror Earth's biosphere. Since you need water, food, and air, you need a solution that provides all 3. Hydroponics (and its closely-related twin aeroponics) is an excellent way to provide food and air: You grow edible plants (especially those with green leaves), which as they are growing consume the ...


14

Fog is just a suspension of minute droplets of water/liquid in the atmosphere. If the atmosphere was breathable before the fog, it stays breathable also with the fog. There are cities in our world where fog is notoriously a major aspect of their life, still they flourish (think London or Frisco). Water based fog can be highly beneficial for life: in the ...


13

Denver has about 17% less oxygen than at sea level. Note that this isn't reduced concentration; there's just less air. This answer doesn't address the increased proportion of other elements in the air, only oxygen reduction. According to this article on altitude sickness, the first effect that kicks in from reduced oxygen is hyperventilation -- you ...


13

One of the very basic things you need for complex Earthly life is water. Human need water to drink, taking baths, washing clothes etc. So the planet you are going to send the pioneers has to have a large body of water. Without this, it would be simply impossible to sustain a human settlement on any planet in the long term. For the sake of this answer, let ...


12

100% O2 At normal atmospherical pressure (101.325 kPa) if your only gas is O2 you will have a partial pressure of 101.325 kPa of O2... lethal, deadly and painful. Lets talk about consequences! Oxygen toxicity: When O2 partial pressure is above 50 kPa oxygen become toxic. Symptoms: Disorientation, breathing problems, vision changes such as myopia. Prologed ...


12

You have to consider the cycle: You need energy to live, how does this work, you eat plant and use oxygen and in effect you breathe out CO2 and water. What a plant does is, breathe in CO2 and take in water and energy (from sunlight) and uses this to make the plant you eat and O2 in the oxygen. And this would be exactly what your vat grown food source ...


11

Your premise with interstellar hydrogen causing decrease in oxygen in atmosphere is NOT plausible. TL;DR: Forget interstellar hydrogen. There is plenty of hydrogen in solar system. For bonus oxygen elimination, you can burn some iron and sulfur, it is plentiful too. Anything which oxidizes would do. But you need to burn huge amounts of material, and the ...


11

The Ship A generation ship carrying one million people for an indefinite period will need to carry or generate a minimum of 550,000,000 litres of $O_2$ per day. Mixed to match Earth atmosphere ratios, in which $O_2$ accounts for 21% of the air, that's a minimal atmosphere capacity of 2,620,000,000 litres. Assuming a classic rotating cylinder ship, that is a ...


11

One of the common misconceptions is that high concentrations of oxygen lead to hotter fires by default; it's actually fairer to say that high concentrations of oxygen lead to faster fires by default, but that in turn can create a hotter fire in certain circumstances. Take a look at this oxygen enriched fire safety article which talks about this in great ...


10

Carbon Dioxide The simplest and most straightforward solution. Deadly to humans at concentrations of around 10% (this is on the high end of 'a few percent by mass' but you said you will take what you can get) Hypercapnia kills you by messing with the carbonic acid concentration in the blood. Since this is just a pH balance thing, it seems pretty easy for ...


10

Coboglobin is one of the main iron- and copper- free proteins that can be used for oxygen transport. It was first synthesized by humans in 1970, where cobalt was intentionally substituted for iron in a hemoglobin-like protein. It also looks like it's been talked about before on Worldbuilding. To have a creature evolve to use coboglobin, you'd want an ...


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