> There are situations where death comes before the threshold of discomfort.
Not for anything we can actually sense. Volume, temperature, pressure - you will feel wildly uncomfortable long before any of these are extreme enough to seriously impact your health.
Is there any example of something we can feel, but we don't feel uncomfortable before it kills us? All I can think of are drugs.
Yes. Search YouTube for high-altitude simulation chambers and hypoxia. I seem to think Derek from Veritasium has a very good demonstration where he gets euhporic and seems unaware that he's severely mentally compromised.
Also, I once helped a friend set up and tear down an art project that was a flying remote-controlled statue, held up partially by a weather balloon full of helium. In tearing down, I didn't want to let the helium go to waste. My first breath of pure helium went fine. My second full breath of pure helium in a row, I barely had enough time to sit down, say "whoah" and cough the helium out before falling down and twitching on the gymnasium floor. A woke up right at the same time my artist friend realized I wasn't joking around. Had I died, I would have felt no pain, not even the slightest discomfort.
Breathing pure helium, I learned you have about 1-2 seconds of warning that you're hypoxic before you pass out. I figured it was more like 15-30 seconds. Luckily, I didn't die, partially because, as a low molecular weight gas, helium has a high rate of effusion, and on my back, it being lighter than air helped it escape my lungs. Argon may very well have killed me because it has a much lower rate of effusion, and (also related to its higher molar mass) it's also heavier than air.
