Years ago I worked in an underground hardrock mine on a mucking crew. Our crew operated LHD (load haul dump) trucks and loaders and basically mucked up blasted rock both ore and waste rock. It was diesel equipment and I think the ambient rock temp was 120*-130*F and 90% humidity. Those old Deutz air diesels ran hot and heated things up as well sitting right next to steel frames and engines. They pumped air conditioned chilled air and had waterbar spray chambers to make it workable or survivable. You'd drink a couple gallons each day and sweat would just roll off just like being in a sauna. The company furnished fruity electrolytes drinking packets to mix in your water. Kind of an awful occupation. I watched folks get puking sick and even pass out from the heat.
