To find out, I got in touch with Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York. First of all, he agrees “popcorn lung” is not the best name in the world. “It’s a little bit of a misnomer, because it almost makes you think the lungs, on close inspection, would look like popcorn,” he says. I didn’t even think of that but now it’s all I can think about.
Horovitz puts popcorn lung in the same “cauldron,” he says, as interstitial lung diseases (ILDs), a large group of disorders causing scarring of the lung tissue. Some ILDs are caused by behavioral factors, like smoking—a condition which Horovitz says is called bronchiolitis obliterans organizing pneumonia, or, hilariously, BOOP. Other ILDs are thought to be caused by chemical exposure—Horovitz cites those suffered by 9/11 first responders as an example. Popcorn lung would also fall in this camp. “It seems to be the case that when you microwave popcorn, especially when you're doing it in these bags, the bag expands, you pop the bag, and the steam and some sort of chemical—maybe some vegetable-oil metabolite—comes out,” says Horovitz.
One’s risk for popcorn lung—and other ILDs—is greatly increased among smokers, though nonsmokers can get them too, particularly if their line of work puts them in frequent contact with dangerous chemicals. “You usually find in the causation some sort of exposure that most of us aren't exposed to. Maybe they live over the Lincoln Tunnel, or they worked in a chemical plant,” says Horovitz. In other words, microwaving popcorn is not so much a cause of popcorn lung as it is a potential correlation. And less so than it used to be—many microwave popcorn manufacturers announced in 2007 that they would remove diacetyl from their products.
While an otherwise healthy person may be unlikely to contract popcorn lung, there is, as always, plenty to be said for using common sense. What that means, in this case, is: Don’t stick your face in a steaming-hot bag of microwave popcorn. Don’t be like the guy who popularized this condition in the first place with a high-profile lawsuit, who ate two bags a day, and inhaled their steam on purpose. “The average person should always be worried about smells in unventilated areas,” says Horovitz. “You're not supposed to mix Clorox and ammonia in your toilet bowl. You should always work in a well-ventilated area any time you're working with chemicals.” That means cleaning supplies and gasoline and paint, but it also, apparently, means microwave popcorn. To protect oneself, Horovitz suggests keeping a window open, or using an “out fan,” or exhaust fan, to keep the room ventilated. Don’t open your popcorn right away, and don’t open it right under your nose. “Let it sit out and try to wait until the gases have escaped,” adds Horovitz.