Please approximate temperature range for bodily destruction by heat/cold
March 19, 2013 3:41 PM   Subscribe

What are the fatal ambient temperatures, cold & hot, for the human body? (total destruction, not just death)

I am writing an essay about the human sensory experience in relation to other things.

Part of what I wish to describe, to make a minor point, is the range between temperatures sufficient to completely destroy the human body by, of course, cold & heat respectively.

to clarify:
a) I don't mean only to cause death, but to utterly obliterate the substance of the body (I can look that up)
b) I don't mean body temperature, but the actual temperature of the environment experienced outside the body
c) If you have to say things like "but you would need to be in space" or "but factor xyz would prevent factor abc under those circumstances," that is totally fine--

I am merely looking for the cold and the hot temperatures that are specifically compossible to full obliteration relative to whatever "ideal" circumstances.

so sorry for the lack of formatting, but my browser is cranky.
posted by herbplarfegan to Science & Nature (20 answers total) 2 users marked this as a favorite
Cold will never do it, no matter how chilly you can hypothetically make it. With heat, I guess you're talking about dehydrating and then combusting the body, leaving only ash, which won't require temperatures all that high. It will depend to some extent on how fast you want said destruction to happen.
posted by jon1270 at 3:46 PM on March 19, 2013 [1 favorite]

OK-- so it seems like I'm not going to be able to illustrate exactly what I wanted to at all.

As long as we're here, for heat, let's say within one interval of "present" time-- 3 seconds.
posted by herbplarfegan at 3:56 PM on March 19, 2013

And for cold, let's demote destruction to "death," and ask for the same time-- 3 seconds.

Makes it wordy, and I'll have to totally restructure, but it will still work.
posted by herbplarfegan at 3:58 PM on March 19, 2013

If by 'obliterate the substance of the body' you mean to render all individual parts of the body completely inoperable, rather than to cause the body to no longer exist, well, then, extended sub-zero temperatures will do, because many cells and vessels will rupture when their contents freeze. The exact freezing point for bodily fluids might depend on electrolyte level, but it seems like it should be pretty high: for instance, blood apparently has pretty much the same freezing point as water.

Remember, our bodies are mostly water, and freezing water expands. Freeze a human, and the microscopic structure of their body's liable to be totally wrecked even if the external appearance is fine.
posted by jackbishop at 4:04 PM on March 19, 2013

And for cold, let's demote destruction to "death," and ask for the same time-- 3 seconds.

I'm no scientist, but I don't think simply a specification of temperature will work for this. I think in a theoretical room at Absolute Zero I'd still live longer than 3 seconds. I think you need to specify more than temperature; that is, you need to specify the medium I've been dropped into as well. I guess it's possible that if I were dropped into a vat of liquid nitrogen or something I might die in under 3 seconds? Alot would depend on how good an insulator human skin is, though.
posted by yoink at 4:05 PM on March 19, 2013

OK that's a good point. I guess I pictured absolute zero acting on a fragile human body in an astronomically short amount of time, and I thought death would be more accommodating, since the context is one where I'm discussing the tiny range of temperature that we can bear compared to the millions of degrees at which stars thrive.

I guess we are left with death by ambient temperature, within an arbitrarily reasonable and unspecified amount of time. (~minutes~)
posted by herbplarfegan at 4:19 PM on March 19, 2013 cases of both heat and cold. This seems like the only way to make it relevant.
posted by herbplarfegan at 4:21 PM on March 19, 2013

And no, by "obliterate" I originally meant "entirely vaporize," but I was asking the impossible. :)
posted by herbplarfegan at 4:29 PM on March 19, 2013

ambient temperature means regular air?

Is the person wearing clothes?
posted by aubilenon at 4:36 PM on March 19, 2013

Regular air, yes.
Say they were wearing the clothes appropriate to the average person being comfortable at room temperature and the temperature in the room suddenly turned to x° (high) or to y° (low) and the person therefore perished, solely by virtue of the heat/cold.
posted by herbplarfegan at 4:41 PM on March 19, 2013

I've got a feeling you're not going to get the nice, precise boundaries you're hoping for here. I think the Yaghan of Tierra Del Fuego are the people who have lived in the coldest climate without use of clothes; it averages about 32 degrees F during winters there. Obviously we can survive (and they did survive) even lower temperatures for certain periods of time. But it's always going to be a "what temperature under what conditions for how much time" kind of problem, not a "beyond this line ye shall not pass" one.
posted by yoink at 4:41 PM on March 19, 2013

It's a thermodynamics question. The temperature you're looking for is dependent on things like the mass of the person in question, the duration of exposure, and the nature of your heat transfer mechanism, i.e. is it radiative, conductive, convective? Without knowing those variables you can't really give an exact answer.
posted by nicolas léonard sadi carnot at 4:53 PM on March 19, 2013

Taking your terms above, I don't believe any degree of chill will cause someone to die instantly, but as your body loses heat to the atmosphere your skin and then deeper tissues will begin to rupture and at some point this damage will probably stop your heart. Any temperature below freezing will do this to you eventually, it's like I said above, just a matter of duration. The heat question is the same but in reverse, heat will get dumped from the atmosphere into your body which at some point will make physiological systems fail, I don't really know enough about the heat response to speculate which would go down first. If you're talking instant total reduction to constituent atoms, I don't really know how to work that out, maybe look at the energy requirements for disassociating covalent bonds.
posted by nicolas léonard sadi carnot at 5:00 PM on March 19, 2013

OK I'll just read about hypothermia and combustion and look for the temperatures at which nerve function, say, on the skin, is destroyed.
posted by herbplarfegan at 5:09 PM on March 19, 2013

As others have said calculating "instant death" scenarios accurately is pretty tricky. But people have come up with some algorithms relating to more gradual death from hypothermia - in air and in water. If a naked person falls into water which is just above freezing temperature then the cold will kill them in 15-45 minutes, for example (assuming, somewhat generously, that a heart attack does not get them first). That data is based on a whole raft of real life cases - the problem with the "instant temperature inflicted annihilation" is that there are not a whole lot of people meeting their end in that way.
posted by rongorongo at 5:32 PM on March 19, 2013

I can't find a cite for this now, but I remember hearing that a person who was stationed in Antarctica died when he coughed and then took a deep breath of air at about -60 degrees Celsius (-76 Fahrenheit) and his lungs basically froze. That wouldn't take very long, but I'm not sure how long it would take for death to follow.
posted by Cheese Monster at 6:01 PM on March 19, 2013

I took another look at my notes:

Forgetting about time factors entirely, what temperature would cause the body to freeze so that a hammer would turn it to dust? I assume I could get this from the melting point of nitrogen, but does anyone have more nuanced knowledge of anything more specific/accurate?
posted by herbplarfegan at 7:16 PM on March 19, 2013

I have doubts that there is any temperature at which the human body would be turned to dust by a hammer blow. For a little more on the subject, see this. Also, for what it is worth, a live human body immersed in a cryogenic liquid like liquid nitrogen is going to gasify the liquid closest to the surface of the body, which will insulate it from the liquid and slow the rate of cooling of the body enough to make any nearly instantaneous freezing impossible. It might actually be faster to dunk a body in something that is liquid at room temperature, but has a fairly low freezing point. Ethanol cooled with dry ice is one possibility.

On the other hand, you seem to have surrendered too early in your quest for the lowest hot temperature that could lead to obliteration any traces of life in short order. One issue already alluded to is that it takes a fair amount of energy to boil off all the water in human flesh and bone, and that the rate of heat transfer is going to be an important factor. At the ~1800F (~1000C) temperatures of a cremation chamber it takes at least hour or two to go from a dead but juicy body to a desiccated, inorganic skeleton. Once the water is evaporated off the flesh, the flesh can burn or otherwise decompose. Most of the dry mass of the flesh will end up as CO2, water vapor and some gaseous nitrogen and sulfur compounds. What is left behind is going to be be a bit of mineral ash, and the mineral structure of the bones (organic material in the bones, like collagen will dehydrate and burn off like flesh).

Those bones are primarily calcium phosphate, which, near as I can tell, melts at something above 1300C. Whether or not a melted skeleton is a sufficient endpoint for your purposes is left as an exercise for the reader. Getting the time to reach that point down to something on the order of minutes, rather than hours, could be a challenge, but might be achievable using sufficient quantities of pure oxygen and a common industrial gas like propane, methane or acetylene.
posted by Good Brain at 9:31 PM on March 19, 2013

As several people have mentioned, there aren't precise temperatures associated with the transitions you're asking about. But the high temperature limit (for survival over a period of an hour, say) is higher than most people would expect. A famous account is that of Sir Charles Blagden; in 1775, he spent the better part of an hour in a room heated to 260°F (130°C), well above the boiling point of water, and came out feeling fine. (Several friends and a dog also came out healthy. A beefsteak that accompanied them was cooked through and hard, though. In fact, there was one additional characteristic of the 260°F air that was absolutely essential for survival; you can figure that out on your own.)
posted by Mapes at 5:50 AM on March 20, 2013

Something else to consider - there is heat and there is temperature - they are not the same thing. With minimal protection you can walk around in 50°F air more or less indefinitely, while 50°F water will kill you in an hour or so. They're the same temperature, but one removes heat from your body much faster than the other.

For similar reasons, if you heat a piece of wood and a chunk of aluminum to 300° and then pick them both up, you'll be able to hang on to one without too much discomfort - the other one, not so much.
posted by Kid Charlemagne at 11:00 PM on March 20, 2013

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