Do frequent flyers catch more colds?

This article first confirms that flying in an airplane increases your chances of catching a cold and then talks about why that is.

Is it true that you’re more likely to catch a cold if you take a flight on a commercial airplane?

The short answer is yes. People who fly catch more colds than those who stay at home.

This question concerns everyone who flies, especially frequent flyers ands those who fly during winter when fellow passengers are more likely to be infected with colds and even influenza.

Martin Hocking and Harold Foster of Canada's University of Victoria have studied the problem of increased colds among airline passengers. In an article for the Journal of Environmental Health Research ("Common cold transmission in commercial aircraft: Industry and passenger implications," 2004) , they reported that 20 percent of passengers who flew on a 2.5 hour flight developed colds within a week.

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.

Commercial jet airplanes fly typically fly at altitudes ranging from 27,000 to 39,000 feet. The air is extremely dry at these high altitudes. Therefore, when fresh air is brought into the plane to supply the passengers ands crew, it is very dry air.

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.