During the recent smokepocalypse, we were told to stay inside with the windows and doors closed until further notice. Does that really help? If you really could seal your house airtight, wouldn't you just run out of oxygen pretty quickly? &#;Air Hoardin'
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Time for another of our patented Dr. Know bogus mathfests, where our quantitative rigor is matched only by our qualitative stupidity! I'll be using imperial units so those of us old enough to remember the now-discredited brontosaurus from textbooks (or, in some cases, from real life) can follow along.
For argument's sake, we'll assume your house or apartment is outfitted with magical, elf-forged super-weather stripping, suitable for submarine screen doors or space travel. We'll further assume 9-foot ceilings and 1,000 square feet of floor space all to yourself&#;9,000 cubic feet of air, all told.
The average American adult uses about 19 cubic feet of oxygen a day. (If you exercise, you use more, but I did specify "American.") Dividing 9,000 by 19 gives you 474 days of air&#;pretty good, right?
Well, not quite&#;recall that only 20% our air is actually oxygen; the rest is nitrogen and other gases. Still, the remaining 1,800 cubic feet of pure O2 is enough to sustain you for about 95 days.
Or it would be, if you had it conveniently concentrated in an oxygen tank. Unfortunately, it's diffused unhelpfully throughout your increasingly suffocating panic room, and your lungs can only extract oxygen from this miasma down to a concentration of 10% or so. This brings your prognosis down to something like 48 days.
It gets worse! The real problem with a sealed room isn't running out of oxygen, it's the buildup of carbon dioxide. You exhale 15 cubic feet of carbon dioxide per day. Within six days, your bomb shelter's air will be an already-uncomfortable 1% CO2, and by day 24, your air will have reached 4% CO2, a level the Centers for Disease Control and Prevention has declared an immediate danger to life and health.
All that said, a week or 10 days of airtight lockdown&#;longer than you might suppose&#;should be eminently survivable. Movies and TV shows where two teenagers get locked in a walk-in cooler and have 12 hours to escape dying as virgins are, apparently, not as realistic as you thought. But I won't say anything if you don't.
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Thread starter
CCWilson
Start date
Apr 15,In summary, the conversation discusses the calculations for determining how long a person can survive in a sealed room of a certain volume. It is determined that carbon dioxide levels would be the cause of death, rather than oxygen levels. The calculations estimate a person would die in around 12 days in a sealed room of cubic feet, assuming there is no water inside. The conversation also mentions the rule of 3's for survival and the effects of extreme temperatures on survival time. Finally, it is noted that the conversation took place in and is now considered closed.
CCWilson
What are the calculations to figure out how long someone can live in a sealed room of a certain volume? Please check mine.
Let's say that the room is 30 feet by 20 feet by 8 feet, or cubic feet.
I believe that high carbon dioxide levels will kill you before low oxygen levels will. Inhaled carbon dioxide is 0.04% by volume, exhaled is a bit over 4%. Inhaled oxygen is 21%, exhaled 15%, a difference of 6%.
A person breathes about 6 liters per minute, or roughly liters/day or roughly 300 cubic feet/day. Thus that person will decrease room oxygen by 300 x 6% = 18 cubic feet/day.
He will increase room carbon dioxide by 300 x 4% = 12 cubic feet/day.
Comfortable carbon dioxide levels are less than ppm (parts per million) (0.1% of room air).
Dangerous levels are above 10,000 ppm, especially above 30,000 ppm. Let's take 30,000 ppm (3% of room air) as our death point, although obviously that's arbitrary.
0.03 times = 144 cubic feet of carbon dioxide in the room would be deadly.
144 / 12 (cubic feet of CO2 exhaled per day) = 12 days to death in that sealed room.
Originally there were (room cu ft) * 0.21 = cu ft of oxygen (rounded)
After 12 days, 18 (cu ft/day of oxygen decrease) x 12 = 216 cubic feet oxygen lost.
That leaves 784 cubic feet of oxygen in the room, or 784/ = a little over 16% oxygen in the air. While people will have symptoms at 15% or less, it would be rare to die with oxygen levels above 10%.
So my conclusion is that in the above scenario, a person would die in around 12 days, and from carbon dioxide toxicity rather than oxygen deprivation. Are my calculations correct on this? Thanks.
Mentor
Insights Author
If there is no water in the sealed room, dehydration will become a problem quicker. If there is water, there could also be devices to filter CO2 ;).
Oxygen consumption and CO2 production will depend on the activity and weight of the human as well.
Julio R
mfb said:
What do you mean by that? Is there a correlation?
Mentor
Insights Author
The only correlation I see is that an empty room has neither, and if the room has something inside we do not know what is inside.
maltman
empty room and life expectancy
empty i understand from the discussion include Earth normal sea level atmosphere and nothing else
have you ever heard of the rule of 3's for survival?
generally in any extreme situation you cannot survive for more than:
3 minutes without air (suffocation)
3 hours without shelter for extremes of temperature (hypothermia or hypothermia)
3 days without water (dehydration )
3 weeks without food (starvation)
you will die if your core body temperature is not within 34C to 39C for an extended period
a typical naked human will die in 10C water within an hour, 0C water in at little as 15 minutes
in contrast, we do a little better with heat, but a sustained wet bulb temperature of 35C can
kill a healthy adult human within 48 hours
you computed a rough idea of breathing time
but you need to consider
to little heat, a few hours
to much heat, maybe a few days
no water - about 3 days
tbrd
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Questions & answers
Such a good question, such silly answers. I was looking for a simple answer on that "how long before they run out of air" scenario so common to Star Trek and its ilk and this is the closest I've seen, and yet everyone seems to want to pollute the scenario with unnecessary complications.
Pythagorean
Gold Member
I'm glad you find unnecessary complications humorous. I say 30 minutes due to the maddening grasp of over-emphasized self-monitoring:
Mentor
Insights Author
... and the first post has a good answer to that.tbrd said:
... and the first post has a good answer to that.
Igitigit
You are wrong because you are making the assumption that 100% of the air is oxygen. We all know that nitrogen makes up most of our air. Ha! I Win.
You are close though. Start at 20% or whatever the real oxygen levels are.
rbelli1
Gold Member
mfb answered the question. You will die in about 3 days due to dehydration.
However you will likely be uncomfortable due to both the dehydration and the excess CO2 before death.
BoB
Mentor
Insights Author
All volumes are total air, the fraction of oxygen is taken into account by using the 6% reduction (relative to the air that entered the lungs).Igitigit said:
All volumes are total air, the fraction of oxygen is taken into account by using the 6% reduction (relative to the air that entered the lungs).This thread is from .
rbelli1
Gold Member
Necropost on a thread about death. Kind of fitting.
BoB
Mentor
Insights Author
I think this thread is done.
The length of time a person can survive in a sealed room depends on various factors such as the size and airtightness of the room, the person's health and physical condition, and the availability of resources such as food and water. Some individuals have been able to survive for several days or even weeks in sealed rooms, while others may only last a few hours.
When a person is trapped in a sealed room, the air supply gradually decreases as the person consumes oxygen and produces carbon dioxide through breathing. This can lead to a decrease in oxygen levels in the blood, causing symptoms such as dizziness, confusion, and eventually loss of consciousness. In addition, the buildup of carbon dioxide can lead to respiratory acidosis, which can be fatal if left untreated.
No, a person cannot survive by breathing in their own carbon dioxide. While it is true that humans exhale carbon dioxide, it is not enough to sustain life. As the carbon dioxide levels increase in the sealed room, the body's ability to absorb oxygen decreases, leading to hypoxia and eventually death.
When the body senses a lack of oxygen, it will attempt to adapt by increasing the heart rate and breathing rate in order to circulate oxygen throughout the body. The body may also go into a state of shock, reducing blood flow to non-essential organs in order to preserve oxygen for vital organs such as the brain and heart. However, these adaptations can only sustain the body for a limited amount of time before oxygen levels become critically low.
Yes, there are some steps that can be taken to increase the chances of survival in a sealed room. These include having a larger, well-ventilated room, ensuring a sufficient supply of food and water, and having access to oxygen tanks or other sources of fresh air. It is also important to try and remain calm and conserve energy in order to prolong survival. However, the best course of action is to avoid being trapped in a sealed room in the first place.
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