Blame Your Nose for That Winter Cold

Conventional wisdom says that you're more likely to get a cold or flu in the winter. Now science backs that up. CNN reports on a "breakthrough" study published in the Journal of Allergy and Clinical Immunology that sheds light on the connection between colder temperatures and increased viral infection. Those colder temps are the linchpin: Researchers found that a 9-degree drop in the temperature within the nose can kill almost half of the virus- and bacteria-fighting cells that reside within the nostrils (and there are billions of them), making us more susceptible. "You've essentially lost half of your immunity just by that small drop in temperature,” said rhinologist Dr. Benjamin Bleier of Harvard Medical School.

HuffPost reports this is an about-face from one long-standing theory, which is that the cold drives people to warmer indoor spaces, where they breathe pent-up air that hasn't been well-circulated. But in looking at the mechanisms that come into play when bacteria is inhaled, the researchers found the front of the nose does a job that the back doesn't. When the cells toward the front pick up on the invading germ, they start creating hordes of basic copies of themselves. These are called extracellular vesicles, or EVs, and they have one noteworthy difference from the original cells: They have way more sticky receptors on their surfaces.

Those EVs are expelled into our mucus (aka snot) where they "act as decoys, so now when you inhale a virus, the virus sticks to these decoys instead of sticking to the cells," says Bleier, per CNN. When study participants spent 15 minutes in 40-degree Fahrenheit temps, the temperatures in their noses sank as much as 9 degrees. The impact? The release of those EVs was cut nearly in half—42%, per the study—by the cold. The implications of the findings? The mask-wearing habits formed by COVID might serve us well going forward, as anything you can do to keep your nose's interior warm is beneficial. (More discoveries stories.)