The next time you let loose with a snarky, "OMG, the boss was running around with his hair on fire," I want you to think of this post.

Because, you see, that actually happens. And one of the most esteemed medical institutions in the country wants to help stop it.

To make matters worse, we're talking about facial hair, not head hair, combusting nearly spontaneously. Neither is a laughing matter, but fires involving facial hair can result in terrible burns to your face and airway. When your airway burns, the tissue swells and can die, a very serious injury that is sometimes fatal and often requires intubation.

The people at risk for this, as you've probably surmised, are the 1.5 million who receive home oxygen therapy--lung disease patients you sometimes see with tubes running from an oxygen tank into their nostrils to help them breathe. After three men with facial hair suffered burns this way over a four-year period, physicians at the Mayo Clinic in Rochester, Minn. combed their own medical records from 1994 to 2013 and found that eight of the nine men who had suffered such burns had facial hair.

The authors--Andrew Greenlund, Laura Greenlund and Bradley Anderson--then drilled nostril holes in two mannequins and hooked them up to oxygen cylinders via that clear plastic tubing, known as "nasal cannula."  One mannequin had a mustache made from human hair; the other did not.

With the oxygen flowing at two liters per minute, a level common in home oxygen therapy, the researchers exposed the mannequin to sparks by grinding a piece of reinforcement bar with a power grinder. "In the models with a mustache, the facial hair and nasal cannula readily ignited. In contrast, the nasal cannula tubing did not ignite in the models without a mustache, strongly suggesting that facial hair increases the risk of [home oxygen therapy]-related burns in the presence of an ignition source," they wrote in the June 22 issue of Mayo Clinic Proceedings.

In an interview, Andrew Greenlund, a primary care physician, said he believes that when home oxygen therapy patients exhale, it stops the inflow of oxygen, which collects in the mustache. A well-timed spark is then much more likely to set the facial hair ablaze, he said. The fire spreads to the plastic tubing, which is full of oxygen and burns quickly, he said.

Home oxygen therapy patients know they're not supposed to smoke and must avoid open flames, but addicted smokers sometimes violate the rules. And that's not the only way these fires are caused. One man was grinding the blades of a lawnmower, another was repairing a scooter and a third was in the wrong place at the wrong time when a match-head from someone else's cigarette flew toward his face.

What else can set these devices ablaze? Well e-cigarettes for one. A Syracuse hospital banned vaping after a patient using oxygen caught fire while smoking an e-cig.

The medical literature shows 266 home oxygen therapy patients have been burned in various ways since 1998, Greenlund said, and 63 suffered airway injuries severe enough to require intubation--an oxygen tube inserted down into their lungs to enable breathing. A NASA study previously identified the combustibility of facial hair in an oxygen-rich environment, the authors noted.

When I asked Greenlund if he would recommend that men receiving oxygen at home remain clean-shaven, he said: "I think you have to be culturally sensitive on that one. If your religion allows shaving , I would recommend shaving. And I’d also push the oxygen tubing companies to use materials that are fire resistant in the presence of oxygen."

(Thanks to @EmilyMBadger at Wonkblog for spotting this one.)