If body temperature is 98.6 F, why do we feel uncomfortable when it’s 90?

Dear Cecil:

If the average body temperature is 98.6 degrees F, why is it that when the air temperature reaches 85 or 90 we feel uncomfortable?

Cecil replies:

One of Cecil’s competitors once wrote that it was because we wore clothes — as though all you had to do to be comfortable in 98-degree heat was walk around naked. Clearly what we have here is a failure to grasp the scientific essence of the thing, namely, that the air temperature has to be lower than body temperature if you’re to cool yourself efficiently.

Your body is a little fuel-burning engine, and like all engines generates waste heat. That heat has to go somewhere, lest you pop a gasket. The easiest place to put it is someplace cooler, such as the air around you. However, if the ambient air temperature is the same as your body temperature, you have to go to great lengths to shove the waste heat out into it, e.g., sweating like a pig or going out to K mart to buy an air conditioner.

What we want, therefore, is an ambient temperature that lets us dump waste heat with the least strain. From experience we know this temperature is 68 to 72 degrees F. If you’re very lightly dressed you may prefer 80. But even if you’re starkers there’s no way you’ll be happy when it’s 98 in the shade.

Send questions to Cecil via cecil@straightdope.com.

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