I work in a factory...it's been extremely hot in Michigan right now too. It's only going to get worse.
My plant has 'climate control', however it's been broke for God only knows how long. It's atleast 10 degrees hotter inside then it is outside, and it's pretty unbarable. Theres nothing that can be done legally, atleast in Michigan. We have a medical department too, and you wouldn't believe how many people are taken there by our little inside ambulance thing ( we call it a meat wagon).
I would suggest to him to drink water AND gatorade or powerade. Because gatorade repleneshes your electrolyte loss (salt, magnesium, and theres 2 more, but I'm heat brain right now so I can't think of the other 2). Also take extra breaks. If he can't take extra breaks, then I would definately be complaining!!