Forrest M. Mims III, author of the world's best practical electronics primer, Getting Started in Electronics, summarizes the findings of a 2004 study on the increased likelihood of catching a cold after flying on a commercial plane.
Depending on three different flight scenarios, Hocking and Foster found that airline passengers in three different scenarios were 5, 23, or 113 times more likely to catch a cold than if they had not flown at all!
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The most logical reason for infections would seem to be the limited amount of cabin air shared by the passengers. But Hocking, Foster and other scientists have found this is only one factor. The very low humidity in an airplane seems to be much more important.
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Very dry air dries up the mucous system that captures and expels bacteria and viruses from our noses. This may be a key reason why airplane passengers catch more colds.
