In this cooler weather, one of our viewers has a question about a natural reaction.

Terry in Stoughton asked: “Why does your nose start to run when the air is very cold? I notice in the wintertime, when I go from indoors to outdoors, my nose starts to run. I have always been curious about this phenomenon.”

Dr. Mallika Marshall has the answer:

When it’s cold outside, your nose goes into overdrive trying to warm the air you’re breathing in before sending it to the lungs.

Tiny blood vessels on the inside of your nose dilate, or widen, to help warm the air. But that extra blood flow leads to greater mucus production and that makes your nose run.

Read the answers to more health questions sent in by WBZ viewers.

If you are curious about something, e-mail us. You can also join the conversation at wbztv.com/curious.

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