I once had to check a sensor that was above a boiler, the air temperature was just over 50 degrees. I walked up steps to about 10m above the ground, the temperature rising the whole time.

I by the time I was around 7m up the air was above 35 degrees and the sweating started in force. The total time in the high temperature area was probably less than 3 minutes. But FFS, 50 degrees is not sustainable for even walking up and down steps, just being there and reading the instrument wasn't too bad (for 2 minutes) as the air is super dry; but any form of exertion isn't doable for people.