After seeing countless sci fi movies where the characters are able to walk around on other planets without masks I was wondering how much would the plantes atmosphere have to be like earths for us to be able to breathe? Would it have to be exactly like Earths or would something like 90% suffice? I was wondering lets say we land on another planet in the future many light years away from earth. We scan the planet and it says that it has -8% the Nitrogen the earth has +5% the oxygen, and +3% the amount of carbon monoxide. Do you think we would be able to breathe on this planet without a mask?
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Short answer: I would guess it would be quite likely for the atmosphere of another, even one that contains oxygen due to the actions of life, to be poisonous. Another interesting question is how long it took earth's atmosphere to be breathable by modern humans. Anyone know?
Do you mean 1.03 * the current amount of carbon monoxide, or carbon monoxide at a level of more than 3% of the atmosphere?
According to this link, carbon monoxide is bad for your health at levels of 100 parts per million, way less than three percent, which is 30,000 parts per million.
http://en.wikipedia.org/wiki/Carbon_monoxide_poisoning
You also might have meant Carbon dioxide: some factoids of the internet:
http://www.inspectapedia.com/hazmat/CO2gashaz.htm
1,000,000 ppm of a gas = 100 % concentration of the gas, and 10,000 ppm of a gas in air = a 1% concentration.
At 1% concentration of carbon dioxide CO2 (10,000 parts per million or ppm) and under continuous exposure at that level, such as in an auditorium filled with occupants and poor fresh air ventilation, some occupants are likely to feel drowsy.
The concentration of carbon dioxide must be over about 2% (20,000 ppm) before most people are aware of its presence unless the odor of an associated material (auto exhaust or fermenting yeast, for instance) is present at lower concentrations.
Above 2%, carbon dioxide may cause a feeling of heaviness in the chest and/or more frequent and deeper respirations.
If exposure continues at that level for several hours, minimal "acidosis" (an acid condition of the blood) may occur but more frequently is absent.
Breathing rate doubles at 3% CO2 and is four times the normal rate at 5% CO2.
Toxic levels of carbon dioxide: at levels above 5%, concentration CO2 is directly toxic. [At lower levels we may be seeing effects of a reduction in the relative amount of oxygen rather than direct toxicity of CO2.]
Do you mean 1.03 * the current amount of carbon monoxide, or carbon monoxide at a level of more than 3% of the atmosphere?
According to this link, carbon monoxide is bad for your health at levels of 100 parts per million, way less than three percent, which is 30,000 parts per million.
http://en.wikipedia.org/wiki/Carbon_monoxide_poisoning
You also might have meant Carbon dioxide: some factoids of the internet:
http://www.inspectapedia.com/hazmat/CO2gashaz.htm
1,000,000 ppm of a gas = 100 % concentration of the gas, and 10,000 ppm of a gas in air = a 1% concentration.
At 1% concentration of carbon dioxide CO2 (10,000 parts per million or ppm) and under continuous exposure at that level, such as in an auditorium filled with occupants and poor fresh air ventilation, some occupants are likely to feel drowsy.
The concentration of carbon dioxide must be over about 2% (20,000 ppm) before most people are aware of its presence unless the odor of an associated material (auto exhaust or fermenting yeast, for instance) is present at lower concentrations.
Above 2%, carbon dioxide may cause a feeling of heaviness in the chest and/or more frequent and deeper respirations.
If exposure continues at that level for several hours, minimal "acidosis" (an acid condition of the blood) may occur but more frequently is absent.
Breathing rate doubles at 3% CO2 and is four times the normal rate at 5% CO2.
Toxic levels of carbon dioxide: at levels above 5%, concentration CO2 is directly toxic. [At lower levels we may be seeing effects of a reduction in the relative amount of oxygen rather than direct toxicity of CO2.]
Thank you for the post. I meant that the fictional planet would have 3% more carbon monoxide than the earth has now.
tpeezy":3q8lqnyk said:
Not only the components of the atmosphere, but what's floating around in it....mold spores, pollens, viruses and bacteria. We have enough trouble handling our own version of these allergens and organisms, much less breathing in alien counterparts and thinking our naive immune systems could handle them!
Hand me a mask...please!
There is a flip-side point about CO2 as well: the human organism requires at least a certain percentage present in the mix for the autonomic breathing reflex to work.
yevaud":25rx7awr said:
Not really, you can breathe 100% pure oxygen. Fighter pilots and military divers do it all the time. Your own body provides the CO² required for the breathing reflex through respiration.
Technical divers breathe many different mixes, like hydrox, heliox, nitrox in different ratios depending on the partial pressures of each gases.
tpeezy:
Don't confuse carbon monoxide (CO), which is a poison present only in trace amounts (0.00001%) in our atmosphere and carbon dioxide (CO²), which is about 0,04% or the air we breathe and something we produce in our own body through respiration. :idea:
Excuse me. But that the diver can breathe various gas mixes has nothing to do with the autonomic breathing reflex. You require a minimal percentage of CO2 present in the air for the autonomic breathing reflex to work properly. If the concentration is too low, when trying to sleep you will keep waking up gasping for breathe - because your autonomic breathing reflex isn't working.
You might give me credit that I do have SOME clue what the hell I'm talking about.
Oh, btw, Oxygen is also a poison to the human organism, and you can only breathe pure O2 for a limited time before having some serious complications.
You might give me credit that I do have SOME clue what the hell I'm talking about.
Oh, btw, Oxygen is also a poison to the human organism, and you can only breathe pure O2 for a limited time before having some serious complications.
The reason they don't wear masks very much in movies or on TV is because with a mask on you can't see the actors high dollar pretty faces.
CO2 is required for the reflex to occur, but it does not have to be present in the air you inhale. It appears in your blood as a result of respiration, which triggers the reflex.Yevaud":8nxtmp46 said:
I did breathe pure O² for many hours and even if the breathing frequency decreases, the reflex is still there.
Besides, O2 is not poisonous as long as it's partial pressure doesn't increase too much. We use to say 8m is the safe limit for oxygen diving, which is about 1.8Bar, for less than 3 hours.
1.6Bar is stated in literature as the trigger partial pressure for toxicity in continuous breathing. At 1Bar standard surface pressure, oxygen is considered to be benign.
http://en.wikipedia.org/wiki/Oxygen_toxicity
Sorry, but your autonomic reflex doesn't trigger off of your own CO2 - it has to be in the presence of CO2 in the air you breathe. It requires it.
No offense, but now that's just plain being foolish. So you were at depth, unconscious? Hmm? When do you ever, medically, see someone on pure O2, unattended? Answer: you will not, unless the person is on a tidal respirator, which does the breathing for them. Or in a Hyperbaric chamber, when that person will be conscious or under observation.
orionrider":3bx3p49i said:
No offense, but now that's just plain being foolish. So you were at depth, unconscious? Hmm? When do you ever, medically, see someone on pure O2, unattended? Answer: you will not, unless the person is on a tidal respirator, which does the breathing for them. Or in a Hyperbaric chamber, when that person will be conscious or under observation.
In rebreather diving we used to breathe pure O² well before the beginning of the mission to scrub all other gases. The dive was done in 100% O² to avoid bubbles and exclude any decompression dangers, whatever the ascent speed. O² also helps with the alertness, visual acuity in the dark and thermal resistance. Diving depth was typically less than 5 meters, occasionally going somewhat deeper to clear obstacles, like a ship's keel. Duration on O² could be anything between 1 and 5 hrs.
http://en.wikipedia.org/wiki/Rebreather
I also did long-duration, high altitude flights at 100% O², at a PP of about 0.7 Bar.
If I recall correctly, the Apollo program planned a 100% O² atmosphere at 0.3 Bar with CO² scrubbers. They changed that after Apollo 1 dramatically proved that it was impossible to manage a fire in a 100% O² atmosphere, even at reduced pressure. However, pure O² is still used for EVA:
http://en.wikipedia.org/wiki/Decompress ... ure_oxygen
I'm about certain that there was no CO² in my inhaled gases, but maybe extremely faint traces is all it takes? Do you have any reference for the need for CO² in the inhaled mixture? I couldn't find any.
http://en.wikipedia.org/wiki/Rebreather
I also did long-duration, high altitude flights at 100% O², at a PP of about 0.7 Bar.
If I recall correctly, the Apollo program planned a 100% O² atmosphere at 0.3 Bar with CO² scrubbers. They changed that after Apollo 1 dramatically proved that it was impossible to manage a fire in a 100% O² atmosphere, even at reduced pressure. However, pure O² is still used for EVA:
http://en.wikipedia.org/wiki/Decompress ... ure_oxygen
I'm about certain that there was no CO² in my inhaled gases, but maybe extremely faint traces is all it takes? Do you have any reference for the need for CO² in the inhaled mixture? I couldn't find any.
Breathing on another planet? Not likely for humans. We are just lucky to be on planet earth, where we are bathed in an atmosphere suitable in concentration of oxygen at an atmospheric pressure that allows us to survive.
It's not really luck, if you think about it. Life has evolved to survive in the environmental conditions that exist here.
yevaud":38g946r2 said:
Yev is correct.
In addition, exposure to low CO2 in fact often is the cause of hyperventilation, which occurs when the subject is awake. That is why breathing into a paper bag often cures hyperventilation within a minute , by increasing the amount of CO2 inhaled, and thus reducing blood pH. As you probably know, hyperventilation is one of the risks that can occur when diving. From Wikipedia:
"Therefore, there are two main mechanisms that contribute to the cerebral vasoconstriction that is responsible for the lightheadedness, parasthesia, and fainting often seen with hyperventilation. One mechanism is that low carbon dioxide (hypocapnia) causes increased blood pH level (respiratory alkalosis), which causes blood vessels to constrict. The other mechanism is that the alkalosis causes decreased freely ionized blood calcium, thereby causing cell membrane instability and subsequent vasoconstriction and parasthesia."
http://en.wikipedia.org/wiki/Hyperventilation
Thanks, Silylene. I couldn't quite locate anything with that direct a reference (I must be slipping!).
Orion: yes, but no matter what you're describing, the one commonality is that you are always conscious. You will make yourself breathe, generally completely unconsciously (which is not the same as autonomic).
Orion: yes, but no matter what you're describing, the one commonality is that you are always conscious. You will make yourself breathe, generally completely unconsciously (which is not the same as autonomic).
I was looking into rebreather CO2 removal efficiency (per pass). Its rather amazing that despite all the technical documents proliferated on diver websites about equipment, there is very little published on this key parameter in the trade literature. I could find the information in the patent publications however.
Reading the patents for various CO2 scrubbers in rebreather designs, depending on design, they are usually about 98% efficient in CO2 removal. So about 2% of the exhaled CO2 is rebreathed, and 98% of the exhaled CO2 is absorbed. Apparently this is enough CO2, when added to the pure O2 in the cannisters, to maintain the required minimum CO2 levels.
Reading the patents for various CO2 scrubbers in rebreather designs, depending on design, they are usually about 98% efficient in CO2 removal. So about 2% of the exhaled CO2 is rebreathed, and 98% of the exhaled CO2 is absorbed. Apparently this is enough CO2, when added to the pure O2 in the cannisters, to maintain the required minimum CO2 levels.
Thanks Silylene, I found no difficulty with hyperventilation, we were trained to control our respiration and avoid triggering HV, for instance when working or swimming. However, panic or breathlessness can rapidly lead to HV, which in turn causes more panic and can have lethal consequences.
Yevaud, now that you mention it I was never asleep and unattended under 100% oxygen but then I never felt anything special while sleeping, except for the mask, itching, condensation, cold, uncomfortable posture,...
I probably never achieved deep sleep :?
I know many aircrew members sleep with the mask on, sometimes for many hours and I have never heard of respiratory distress, but that's not something people normally talk about.
I wonder what Nasa intended for the early Apollo crews? Maybe the scrubbers were designed to leave a small amount of CO²?
How much CO² is required? Maybe the tiny amount exhaled in the piping and mask is enough? There is always some exhaled air coming back.
In the unlikely case of a planet completely devoid of CO² but rich in O², maybe a simple paper mask would be enough. Or sleeping indoors :?:
Yevaud, now that you mention it I was never asleep and unattended under 100% oxygen but then I never felt anything special while sleeping, except for the mask, itching, condensation, cold, uncomfortable posture,...
I probably never achieved deep sleep :?I know many aircrew members sleep with the mask on, sometimes for many hours and I have never heard of respiratory distress, but that's not something people normally talk about.
I wonder what Nasa intended for the early Apollo crews? Maybe the scrubbers were designed to leave a small amount of CO²?
How much CO² is required? Maybe the tiny amount exhaled in the piping and mask is enough? There is always some exhaled air coming back.
In the unlikely case of a planet completely devoid of CO² but rich in O², maybe a simple paper mask would be enough. Or sleeping indoors :?:
Now that we get down to it, is it possible for a planet to be rich in O2, but devoid of CO2? I personally doubt it - unless there's some other biological cycle I am unaware of, in which a different gas is a byproduct of life.
I think it would be VERY hard to have a planet rich in O2 and devoid of CO2, for example like earth (which is nearly devoid of CO2, only 320 ppm). If you saw this combination, I would think it is a possible signal of life.
Why? Well O2 is a very good oxidizing agent - it will oxidize almost everything which is unoxidized. So if there were any unoxidized carbon species around, or carbon bonded to less electronegative atoms than oxygen (for example CH4), the carbon will eventually get converted to CO2 or carbonate ion.
So the absence of CO2 in the presence of lots of O2 could mean that there is an active process on the planet actively removing the CO2 from the atmosphere, such as life.
I guess the only other likely way one could find O2 and not any (or hardly any) CO2, and no life, would be if there were large highly alkaline oceans, which would also scrub CO2 from the atmosphere.
Any other combination which could have the combination of high O2 and no CO2 gets unlikely, for example large deposits of KO2 minerals (potassium superoxide) on a water-free planet surface, or something crazy like that.
Why? Well O2 is a very good oxidizing agent - it will oxidize almost everything which is unoxidized. So if there were any unoxidized carbon species around, or carbon bonded to less electronegative atoms than oxygen (for example CH4), the carbon will eventually get converted to CO2 or carbonate ion.
So the absence of CO2 in the presence of lots of O2 could mean that there is an active process on the planet actively removing the CO2 from the atmosphere, such as life.
I guess the only other likely way one could find O2 and not any (or hardly any) CO2, and no life, would be if there were large highly alkaline oceans, which would also scrub CO2 from the atmosphere.
Any other combination which could have the combination of high O2 and no CO2 gets unlikely, for example large deposits of KO2 minerals (potassium superoxide) on a water-free planet surface, or something crazy like that.
Mars is a good example of a planet where almost all the oxygen is found in oxides and atmospheric CO2. Maybe in a few billion years, all that will remain on Earth will be CO2 and some N2.
CO2 - or lack thereof - would probably still be a small nuisance compared to other gases like H2S or even fine dust. If they ever build habitats on Mars or the Moon, dust is going to be a major health concern.
CO2 - or lack thereof - would probably still be a small nuisance compared to other gases like H2S or even fine dust. If they ever build habitats on Mars or the Moon, dust is going to be a major health concern.
Some variation is ok and considerable variation short term for selected persons. Over one part per million of carbon monoxide is considered polluted air. Zero to 3% for carbon dioxide, 10% briefly which is 250 times the normal content of 0.04%. 16% to 25% for oxygen, some persons can adapt to a wider range. 0.1% to 1% water vapor helps prevent chapped lips. For humans, nitrogen is a filler, so not critical as long as other gases are in the good range. Most of the noble gases can substitute for nitrogen. Argon (also a filler) is a bit less than 1%. I'm assuming the air pressure is 14.7 pounds per square inch. At half that pressure we need a bit more than twice as much oxygen. at double that pressure we need about half that much oxygen. The fire hazard increases rapidly at high percentages of oxygen at high pressure.
Planets without life likely won't have an atmosphere that humans can breath, as we think planets have an oxygen atmosphere because green plants take carbon dioxide from the atmosphere and excrete oxygen = photosynthesis. Neil
Planets without life likely won't have an atmosphere that humans can breath, as we think planets have an oxygen atmosphere because green plants take carbon dioxide from the atmosphere and excrete oxygen = photosynthesis. Neil
Yeah, with Mars it's a serious problem. The prevailing surface is very fine, and (I don't remember the precise substance - whereinthehellis Jon Clarke when you need him?! )) somewhat toxic when in concentration. Certainly some form of Silicosis would be a real danger.
)) somewhat toxic when in concentration. Certainly some form of Silicosis would be a real danger.It is unlikely that, should we find another planet with life on it, that any of the organisms there that are analogous to our viruses, bacteria etc. would be a problem for humans unless they were simply poisonous. Bacteria and viruses evolved on Earth to react with only specific cells in a limited variety of organisms. Without the genetic match up, they would be no more biologically dangerous to us than common dust.starsinmyeyes44":sto52do9 said:
so basically there is no way what so ever unless we do some kind of genetic alterations, or use some kind of device that we could ever breathe on another planet without a mask. Even if the planets atmosphere is 95% the same as earths? Excluding spores, Viruses,Bacteria,etc.
yevaud":br6zin8i said:Yeah, with Mars it's a serious problem. The prevailing surface is very fine, and (I don't remember the precise substance - whereinthehellis Jon Clarke when you need him?!
There has been some panic-mongering about supposed hexavalent chronium in martian dust. But no actual evidence that it actually present, let alone at levels to worry about.
Likewise some people worry about the supposed peroxides, again, evidence that they are in srerious quantities is lacking.
Basically any dust is bad, so will be kept to within acceptable limits. and provided the air breathed is kept to this peroxides and hexavalent chromium won't be an issue.
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