When my daughter was a little kid, we discovered that she is allergic to heat. Have you ever heard of such a thing? Officially termed heat-induced urticaria, her body reacts to heat the same way it would react to say, pollen, for example. So, as a youngster at school, it was very awful for her to go out for physical education or recess. The doctor did give her a prescription for antihistamines, but we usually would try to have her take less medicine rather than more. We soon discovered that the best medicine for this condition is air conditioning. A good HVAC system is the best antidote. We live in the southeast, so avoiding heat is difficult, but once inside, almost everyone runs their HVAC unit, so that is very helpful. Later, when my daughter grew up and began to go more places, we discovered that it is not just heat that gives her urticaria, it is also cold weather. Her boyfriend has family in the midwest where it gets very cold. She went there to visit with them, and she was broken out in hives the entire time. It was much worse, there, actually, probably because she had a reaction when she went outside, because it was so cold, but she also had a reaction a lot of the times indoors as well. Why? Because the heaters would be on and would heat the air so much. The furnaces are very efficient in lots of midwestern towns, and so the poor girl suffered no matter whether she went outside or stayed inside.