As for the Arnold expo, I was there and I'm pretty sure whenever you get 20,000-30,000+ people all in the same room the ventilation won't be as good. If you walked outside of the expo area where the vendors and such were, it was cooler, but you also have to remember it was FREEZING outside and snowing. What was funny was seeing some people where sleeveless under armour shirts outside in the snow and walking around like it was nothing.