Vaping is having its moment. It’s never been more popular — or risky.

The name-brand stuff probably won’t kill you immediately as long as you stick to nicotine. But gray-market products supposedly containing THC or CBD are another story, and the jury’s still out on the long-term effects of nicotine vaping.

Most of the 26 vaping-related deaths in the United States have involved cartridges containing the psychoactive compound in marijuana, legalized in more than half the states. But THC has never been shown to cause a death, nor has CBD, a non-psychoactive substance in marijuana. Some products sold as CBD, however, are infused with synthetic THC, which has caused life-threatening reactions, including the hospitalization of a Citadel student.

Researchers suspect the culprit in the recent deaths is the medium in which the THC was suspended: vitamin E acetate, which is harmless when ingested or used topically but may be toxic when inhaled.

The deaths have rightly prompted the U.S. Food and Drug Administration to urge people to stop vaping THC altogether.

In theory, inhaling a cloud of atomized nicotine from a goopy, flavored medium such as glycerin or propylene glycol probably isn’t as harmful as smoking tobacco. But it can be just as addictive, and young people who start vaping are more likely to switch to cigarettes and become tobacco users. That’s reason enough for concern after decades of falling smoking rates.

Nicotine is indeed a powerfully addictive drug. But it doesn’t cause cancer. It’s the roughly 100 known carcinogens, such as formaldehyde, benzene and carbon monoxide, and about 600 other suspected carcinogens in tobacco smoke that can kill you.

Unfortunately, the long-term effects of vaping remain unknown. Could the mediums used in nicotine vaping products cause the same sort of respiratory illnesses responsible for the recent deaths?

That’s an especially poignant question in light of a nicotine-only vaping-related death in Nebraska. Though John Steffen had been a long-time cigarette smoker before he started vaping and had serious health problems related to smoking, the state health department concluded that vaping contributed to his death at age 68, according to The New York Times. One pulmonologist told the newspaper she suspected that up to 30 percent of the people with vaping-related illnesses — about 1,300 cases have been reported so far — used nicotine only.

Certainly, it’s something the FDA and other regulatory agencies need to investigate. Several government-funded studies are underway to assess the health effects of vape “smoke,” including the inhalation of volatile organic compounds and ultra-fine particles such as metals.

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In a recent study published in the New England Journal of Medicine, Mayo Clinic researchers found evidence that lung damage had not come from oil inhalation but “direct toxicity or tissue damage from noxious chemicals.” (Separately, the rechargeable batteries used to heat vaping liquids have also exploded, causing injuries and fires.)

These are all reasons for extreme caution. Massachusetts has temporarily banned the sale of all vaping products, and President Donald Trump has proposed banning all flavored vaping products, something the FDA is working on.

Even if researchers at the Centers for Disease Control and Prevention are soon able to pinpoint the cause or causes of the acute illnesses, doctors have warned that it will likely take 20 years or more to gauge the subtler, long-term effects of vaping.

Common sense should tell us that inhaling anything other than fresh air is harmful.