Allergies are another big reason people turn air conditioning on. That's the close #2 motivation for me -- especially in the spring.

This has turned into a very interesting discussion. A/C has tremendously influenced building design -- homes and commercial buildings -- and that would have severe repercussions were power ever to go out for several days, let alone weeks or months or years.

A/C has influenced where a lot of people are willing to live in this country. My DC neighborhood, with its brick rowhouses, brick sidewalks and asphalt is 10 or more degrees warmer on a hot evening than the National Mall -- where there is usually at least a breeze at night and the two-mile expanse of grass does not retain heat like brick and asphalt do. On hot days, like this past weekend, fellow dog peops and I drive our pups down to the mall after 7:00p to walk them.

In California and Oregon where I grew up, there might have been a week or so every summer when I wished we'd had A/C. But we just ran a lot of window fans and dealt with it, no big deal because those supremely hot days were rare and humidity would not be something I monitored until moving east.

In DC, especially in the most densely populated sections where there is zero space between homes or office buildings, it would be for many residents not just extremely uncomfortable but downright dangerous. Friends who are from the Gulf Coast think I'm a weenie and don't really know oppressive humidity. Having been to Tampa in July, I agree with them -- whoa -- that has to be experienced to believe. But what we have is bad enough. Actually, this summer is the coolest since I've lived here or any of my neighbors can remember. Still, the a/c runs.

Another ramification of A/C is that before its advent, Congress used to be in session a lot less in the summer.

That was surely an unanticipated and profound consequence....

;-)