Some people hail vaping as a safer alternative to cigarettes, arguing that there's no tobacco smoke, so it's got to be safer. It remains to be seen if that's true, and there is some evidence that the stuff inside vapes and e-cigs is toxic. But beyond that, there’s the fact these things occasionally blow up.

You hadn't heard about this? Some pretty gruesome reports are starting to pile up. In November, a man in Colorado broke his neck, lost some teeth, and suffered burns and facial fractures when his e-cigarette exploded. A 15-year-old California boy lost half a dozen teeth in a similar mishap last month. In Tennessee, another teen is recovering from the severe burns caused when a vaping pen caught fire in his pocket a few weeks ago.

Statistics outlining just how prevalent this is remain thin, but the Federal Emergency Management Agency, of all things, identified 25 cases of e-cigarette explosions in the US between 2009-2014. However, that list is based only on incidents reported by the media. Given that vaping's seen a surge in popularity since then—last year, the CDC reported a three-fold increase among middle- and high school students alone—the number almost certainly is rising. A quick Internet search shows at least a dozen explosions in 2015 alone.

The culprit, to probably no one’s surprise, is the lithium-ion batteries.

Hot N' Cold

Instead of burning tobacco, vape pens and e-cigs use a small lithium-ion battery to heat an aerosol cartridge to release a vapor that’s inhaled. As in any device that uses lithium-ion batteries, you can run into problems when the battery is damaged or subjected to extremes in temperature. A short circuit can cause the battery to overheat, catch fire, or even explode. These problems tend to occur in cheap consumer gadgets that are quickly churned out of factories. All in all, it's relatively rare, but obviously it happens—most recently, in hoverboard scooters.

“With lithium-ion batteries in general, when you operate one outside its safety window, there’s a tendency where things can go wrong,” says Venkat Viswanathan, who teaches mechanical engineering Carnegie Mellon University. That window is startlingly small: Viswanathan says batteries are best kept between 50 and 115 degrees Fahrenheit. It's February, and all but four US states are averaging temperatures below 50 right now.

In some cases, the problem is compounded by cheap lithium-ion batteries that "don’t have the luxury of using sophisticated management systems,” Viswanathan says. That can lead to dangerously over- or under-charged batteries. Dendrite is another potential problem. Dendrite is a conductive filament that can form over the course of several charge/discharge cycles, especially if the battery is rapidly charged. This stuff can spread like a weed, eventually bridging the electrodes and causing a short circuit. “You have basically something equivalent to gasoline inside your lithium-ion battery," Viswanathan says, "and so immediately it catches fire.”

Lithium-ion batteries power a whole lot of gadgets of course, and often do so without trouble. But things like mobile phones and laptops and electric vehicles typically are manufactured to exacting specifications and rigorously tested, both by the company and outside experts. The Smoke-Free Alternative Trade Association, which represents for vape-makers, said it "cannot speak to user error or on behalf of a manufacturer for their device" and, "If there is truly an issue with a specific device, similar to a lap top or cell phone manufacturer, that company should take the appropriate action."

And to be fair, it's not uncommon for users to modify their vaping devices, and any number of websites offer tips on how to do just that. The industry trade group duly notes that hacked and modded devices can pose a safety risk.

Smoking Rules

All of which begs the question what, if anything, is being done about this. Most regulatory discussions about e-cigarettes and vapes focus on the Food and Drug Administration's critique of the chemicals found in the devices. The FDA is about to introduce rules regulating the industry, a move that could classify electronic cigarettes and vaping products much like tobacco. Products would carry warning labels, sales to minors would be banned, and you'd see restrictions on things like offering free samples. But little has been said about the safety of the devices.

The Smoke-Free Alternative Trade Association says it supports "reasonable science-based regulations," but opposes anything that might "stifle innovation." But it argues "e-cigs and vapor products are technology products, separate and distinct from combustible tobacco.” They liken them to consumer electronics.

That's where things get tricky. Asked if it has any safety concerns about the devices, the Consumer Products Safety Commission deferred to the FDA, saying it is the federal regulator in charge there. The FDA does claim responsibility for ensuring the safety of the parts in the devices that are used in the consumption of tobacco products. But there aren't a lot of safety rules for manufacturers to follow, and the FDA is encouraging people to report any problems.

Better Batteries

Viswanathan has a recommendation for companies making vape pens and other gadgets that use lithium-ion batteries: Crib from automakers making electric cars. They've developed sophisticated systems for minimizing the risks of problems. “Lithium-ion batteries fundamentally are prone to catching fire," he says, "and car makers have found efficient ways to create zones where these batteries are safe to operate.”

Granted, the odds that your vape pen will blow up like an exploding cigar are slim. But it is possible, so your best bet is to buy a quality vape pen from a reputable manufacturer. Check the parts—if they look and feel cheap, they probably are. Viswanathan suggests making sure it's got some kind of battery management system to prevent shorts and thermal runaway. Make sure you're using the right battery and charger, and don't modify anything.

And you'll probably want to avoid vaping on a hoverboard.