Your mom was right ... the cold air outside just might make you sick. Or, more accurately, it could make you more susceptible to getting sick. This is according to a new study that says the common cold virus thrives in a cold nose.

Researchers at Yale University have shown that the human immune system gets weaker as the temperatures drop, allowing more time and opportunity for cold viruses to take hold. The study, which was published in the Proceedings of the National Academy of Sciences, compared infections caused by the rhinovirus — one of the primary causes of the common cold — at two temperatures, 33 degrees Celsius (about 91.4 degrees Fahrenheit) and 37 degrees Celsius (about 98.6 degrees Fahrenheit or normal body temperature.)

Researchers found that at the colder temperature, the immune system was weakened in two important ways. First, the sensors in the nose were less likely to detect an infection, and thus less likely to start fighting it off. Also, the immune response that was initiated was less effective at cooler temperatures. Thus, colder temperatures in the nose weakened the immune system and gave the virus more opportunities to replicate.

This study confirms previous research showing that the nose is the preferred breeding ground for the common cold, and it explains why colds hit so much more frequently in the winter months.

So what do the researchers recommend for avoiding colds? Move to a tropical location! Or at the very least, cover your nose with a scarf before you head outside. While most of us would prefer option A, option B is probably a bit more realistic.

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