I wouldnt be worried about more than a few minutes. Millions of people live in climates where it gets above 100F for a significant part of the year. I used to go for hour long runs over lunch in Phoenix during the summer. Typically 100-107F. Dry/arid is actually preferable to humid ("yeah, but it's a dry heat").
I'm not saying that 100+F degree air is not livable, just relaying non-medical personal experience. I'm not doubting there were other factors, other then the heat, but it was more then just unpleasant. I've been to arizona in the summer (though I'll admit, I didn't go for long runs), but being inside that datacenter was considerably worse. Could have been the shock/drastic temperature difference though, I suppose.
