It is hard to imagine that prior to the 1940’s, and going all the way back to the dawn of time, people just toughed out the summer heat (except the lucky few who lived in caves). At the signing of the Declaration of Independence on July 4, 1776, it is probable that John Hancock and the guys, in their elegant eighteenth century clothing, were drenched with perspiration. They didn’t bathe that regularly, either, because their water was all drawn from hand pumps.
Air-conditioning offers obvious health benefits for those with heart conditions, pollen allergies and skin problems exacerbated by sweating. It does, however, pose a few problems. For one thing, it moves air around, which tends to whip up dead skin particles (“H.flora”) and bacteria that can spread disease and cause eye and skin dehydration and itching. Also, constant wind from the air-conditioner can make beneficial moisture evaporate more rapidly from skin and eyes. And air-conditioning causes air to lose humidity (cooler air is not capable of holding as much moisture as warmer air—hence the condensation on the outside of the air conditioner), so the resulting air is not only cooler but drier.
Natural air exchange is important in all seasons because outdoor air is usually “fresher” and contains fewer bacteria than indoor air. It’s a good idea to turn the air-conditioning off once in a while in summer, open the windows and let an exhaust fan scour out the air in your house (not a bad idea in winter, either).