Fraser Cunningham lives in Madeira, Ohio. Every morning, he leaves his house at 5:30 a.m. and bikes 27 kilometers (17 miles) to his engineering job. The avid cyclist says he enjoys making the two-hour trip year-round—even in the winter, when temperatures can drop well below zero. On those days, Cunningham often arrives at his office with what look like icicles dangling from his mustache and beard. Those icy adornments are actually chunks of frozen snot!
It’s common for a person’s nose to run when it’s extremely cold outside, says Dr. Soroush Zaghi, who treats disorders of the ears, nose, and throat at the Breathe Institute in California. The reason has to do with mucus-secreting structures inside the nostrils called turbinates. These ridges act like the pipes of a radiator. But instead of carrying heated water, the turbinates produce mucus to warm and moisten the air a person inhales. “The turbinates have to work harder when the weather is cold,” says Zaghi. Cold air is extremely dry, so the turbinates create even more slippery snot to make the air traveling to the lungs more humid.
In Cunningham’s case, the excess mucus running from his nose gets caught in his facial hair and freezes in the chilly air. Water vapor he exhales with each breath only increases the size of the snot-sicles that appear to sprout from his beard. “When humidified air leaves your nose, it quickly condenses in cold weather and becomes a liquid that drips from your nostrils,” says Zaghi.
Cunningham defrosts his face by splashing it with warm water in the bathroom. Once snot-free, he fixes a hot drink to warm up the rest of his body.