At what temperature will your eyeballs freeze?

[Machine_Elf]

@cjepson

I hope y’all will pardon the hijack, but this reminded me of something I read in a book on Antarctica. At some extremely low temperature (around -60 F, perhaps?), just breathing the air will cause you to eventually die of hypothermia, no matter how warmly you’re dressed.

I just did the math. Short answer? Not true.

Longer answer:

Assume absolutely dry air is inhaled at ambient temp, and that air is then exhaled at body temperature (37C) and 100% relative humidity. Heat is lost from the body due to the warming and humidification of that air.

Assume typical parameters for an adult male at rest: 16 breaths per minute, 1/2-liter tidal volume.

Assume ambient temp of -60C. I calculated heat loss via respiration to be 29 watts. For reference, heat loss (via respiration) when ambient temp is 0C is 19.2 watts, so the heat loss at -60 is only an additional ten watts on top of that. (humidification requires an impressive 13.2 watts, no matter the ambient temperature; this is why the total power requirement doesn’t drop that rapidly with increasing ambient temp.)

Various web references indicate that a normal human bean at rest produces 60-90 watts of heat. If your body is perfectly insulated, you’ll eventually overheat since you’ll only be dumping 29 watts through respiration.