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Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,

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Speaker 1: Lauren vocal bomb here, raise your hand. If a parent, grandparent,

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Speaker 1: or an older, wiser caretaker of any kind has scolded

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Speaker 1: you for not bundling up when the temperatures drop, if

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Speaker 1: you're waving your arm frantically, you're far from alone. Across

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Speaker 1: cultures and geographical boundaries. There seems to be a long held,

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Speaker 1: pervasive belief that sudden meteorological changes automatically trigger colds and flus.

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Speaker 1: But does the theory really pan out well, Yes and no.

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Speaker 1: According to health experts, weather driven sickness is a thing,

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Speaker 1: but the temperature itself is more of an indirect cause

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Speaker 1: of the resulting illness. In other words, it's not the

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Speaker 1: cold itself that makes you sick, but the environmental factors

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Speaker 1: related to it. A two thou two meta analysis found

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Speaker 1: that exposing your skin too chilly temperatures doesn't automatically make

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Speaker 1: you more susceptible to the common cold. What does likely

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Speaker 1: set you up for sickness is the drop in humidity.

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Speaker 1: Associate did with that sudden drop in temperature, The mucus

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Speaker 1: membranes in your eyes, nose, and lungs all dry out

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Speaker 1: those mucus membranes are your first, gooeyest line of defense

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Speaker 1: against bacteria and viruses, so losing the goo makes you

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Speaker 1: more susceptible to sickness, and because viruses are more likely

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Speaker 1: to survive and replicate in cold than in heat, you're

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Speaker 1: more likely to get sick when the weather turns frigid.

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Speaker 1: Study Columbia Universities Jeffrey Shaman and his colleagues compared thirty

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Speaker 1: years worth of climate records to health records. They determined

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Speaker 1: that flu epidemics almost always followed a drop in air humidity.

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Speaker 1: Their evidence was reviewed in a study and replicated again

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Speaker 1: in a two thousand nine analysis of the swine flu pandemic.

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Speaker 1: The research paints a pretty compelling picture of why and

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Speaker 1: how dry air fosters this kind of cold and flu

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Speaker 1: free for all. When there's moisture in the air, the

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Speaker 1: particles we release from our noses and mouths when we

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Speaker 1: cough and sneeze stay large, but in dry air they

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Speaker 1: break into tiny pieces that can stay suspended in the

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Speaker 1: environment for hours or even days, creating a virus filled

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Speaker 1: cloud for us to inhale. Furthermore, when it starts getting

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Speaker 1: cold or more likely to stay indoors for more of

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Speaker 1: the time, exposing ourselves to that virus soup. One easy

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Speaker 1: trick to lowering your risk for illness during the colder

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Speaker 1: months is to run an air humidifier. Study found that

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Speaker 1: doing so for just an hour a day could kill

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Speaker 1: thirty of the airborne viruses in schools. But, like everything

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Speaker 1: else in life, balance appears to be key since some

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Speaker 1: pathogens like mold actually thrive in human environments, and of course,

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Speaker 1: relying on good old standbys like vaccines and hand washing

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Speaker 1: is always a good idea to reduce your risk, whether

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Speaker 1: you bundle up in cold weather or not. Today's episode

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Speaker 1: was written by Michelle Kunstantinovski and produced by Tyler Clang.

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Speaker 1: For more on this and lots of other bundled topics,

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Speaker 1: visit our home planet, how stuff Works dot com.