You sweat! My hubby is a carpenter and has worked outside all his life. I don't know how he does it. My son is a UPS driver and their trucks aren't air conditioned and barely heated. You just deal with it. My husband told me the other day when I left for work to enjoy my air conditioned office! I do feel bad for them on these horrible days.
Sorry to hear you have bad allergies. My son has them too and I know it's not fun.