I don't doubt those temperatures at all. But do you know what the relative humidity was? It's the combo that causes problems fast. 100 F and 60% RH is miserable and dangerous, but that's a wet bulb of about 90 F, so there's some marginal potential for your body to cool itself. 100 F and 95% RH is a WB of 98.6 F. Any heat generated in your body has no where to go.
Oh, I didn't mean to imply I experienced any force field effects. I dont recall the humidity, but I do recall looking up OSHA rules regarding heat, and they only offer "guidance", nothing is regulated or enforced solely based on the temperature but they do reference relative humidity.
A funny thing happens to those who live or train in extreme environments, their body adapts over time. You or I might pass out if we were suddenly exposed to that sort of factory environment, but an experienced worker might handle limited exposure just fine. The human body is amazingly adaptable.