Monday, May 30, 2016

Too Much Bang For the Buck: Exploding E-Cigarettes

Last June, a man named Hamid Sadeghy was installing a car windshield in Austin, Texas when he felt a vibration in his pocket.  Sadeghy, who owns his own auto-glass company, is a responsible person who had been trying to cut back on his cigarette habit for the previous month or so by using electronic cigarettes (also called e-cigs or vapes).  Suddenly, in Sadeghy's words "It was like a firecracker.  It made the same exact noise.  A hissing sound and then burning sensation."  An e-cigarette in his pants pocket had exploded.  He suffered severe burns on his thigh which caused him to have difficulty walking, and was not able to return to work for three weeks following the accident. 

Sadeghy is one of dozens if not hundreds of people who have been affected by e-cigarette explosions.  Ironically, many people use e-cigarettes for the same reason Sadeghy did:  as a less harmful alternative to conventional smoking.  Although the jury is still out on the health hazards of e-cigarettes, there may be something to this idea.  But it changes the picture if every time you light up you're taking a chance that what you're smoking will turn into a pipe bomb.

The phenomenon of e-cigarettes showed up in the U. S. around 2007, and a 2015 poll showed that about 10% of U. S. adults now use the product at least occasionally. Vape shops have sprung up in many places, and most convenience stores carry them.  (Interestingly, the major tobacco companies dominate the convenience-store market channel.)  So if even a few hundred people have had their e-cigarette blow up on them, it is still a very rare occurrence, on the order of one incident per year for every 10,000 to 100,000 users.

Still, the tip of the injury iceberg of e-cigarettes is pretty grim, not to mention the property damage caused by fires.  A recent article on Buzzfeed shows graphic photos of Joseph Cavins, whose exploding e-cigarette destroyed one eye, and Thomas Boes, who lost three teeth in a disfiguring explosion from the same cause.  It's not clear whether such highly publicized stories are responsible for a recent slowdown in the growth of the e-cigarette market, but it's certainly possible.  It's well known that a few really exotic and gruesome accidents can cause more popular fear than a much larger number of less chilling mishaps.  This is why some people will get in a car without thinking but refuse to fly under any circumstances, even though the risk of accidents per mile traveled are much greater in automobiles.

A federal agency called the U. S. Fire Administration (USFA) did a study in 2014 of accidents and fires caused by e-cigarettes, and found that about four out of five happened during charging.  Most of the units use a universal-type USB connector to charge the lithium-ion battery that provides the power to heat the vaporizing element.  Unfortunately, this connector will fit pretty much any USB outlet, including power sources that were not designed to charge the particular battery that the e-cigarette uses.  The USFA thinks that most of the fires happened when the user tried to charge their unit with a power source not designed for it.

Lithium-ion batteries are nasty chemically, even when they are not enclosed in a cylindrical metal structure that unintentionally forms a pipe bomb.  The electrolyte is flammable.  If such a battery is charged too fast, it overheats, the liquid electrolyte vaporizes and breaches the battery case, and the thing catches fire.  The fire raises the pressure inside the metal tube of the e-cigarette, and here's where the pipe-bomb analogy comes in.  Small tubes can contain much higher pressures than other shapes, and so the tube doesn't give out on the sides.  Instead, the end cap or caps blow off, but only after the pressure has built up to an extremely high level.  When a cap lets go, the flaming electrolyte shoots it off with the force of a projectile and sprays itself all over whatever is nearby.  If the unit's being charged, that may be only things like flammable paper or wood. 

But in the fairly rare cases when the battery fails while in use, this sequence of dire events can go off in your face, with tragic and disfiguring results.  Properly designed and manufactured lithium-ion batteries don't explode spontaneously as they are charged or discharged, but the technology is being pushed pretty hard even when an e-cigarette operates normally.  A current of an amp or more is needed to heat the vaporizing element, and some counterfeit or shoddily made batteries can't handle that reliably and end up with an internal short due to overheating.  The result is pretty much the same as with overcharging:  electrolyte vaporizing and an explosion.

The Buzzfeed report says that the U. S. Food and Drug Administration (FDA) is moving to regulate e-cigarettes, bringing them under the same regulatory umbrella as conventional tobacco products.  Their plan is to require sellers to apply for authorization to sell the units, with approval hinging on safety features such as overcharging protection circuitry.  Of course, this would make the units cost more, but the present situation that makes it easy to connect an e-cigarette to the wrong charger is clearly a bad one.

Fire has a way of showing up in the early stages of many electrical products.  For a few years I worked at a division of Motorola which made two-way radios for first responders, and learned something about the history of the company, which goes back to the early days of radios installed in automobiles around 1930.  Back then it seems that the company rushed some auto radios into production that were not sufficiently safety-tested, and the resulting burned-up cars nearly killed Motorola.  Fortunately, they figured out what was wrong and fixed it, and car radios became one of the company's mainstays for many years.

The vaping industry needs to clean up its safety act by changing the charging method so consumers can't accidentally make little time bombs by plugging an e-cigarette into the wrong charger.  This will require coordination among the dozens of largely Chinese e-cigarette makers that up to now are probably engaged in cut-throat competition, and may not happen unless the FDA imposes the requirement on them.  So it will be interesting to see what happens in that regard.  In the meantime, if you happen to be a vape-er (?), be sure to use only the charger that came with the unit.  And it might not be a bad idea to wear safety glasses while you smoke.

Sources:  I thank my wife for pointing out to me the article on Buzzfeed from which I learned of this problem, posted on May 26, 2016 at  
-->  I also referred to a vaping website called IEC where an (admittedly unscientific) survey of thirty e-cigarette accidents is reported at  This site refers to the USFA study, which is available at  Mr. Sadegh's story was reported by Fox News on June 30, 2015 at, and the statistic that about 10% of U. S. adults use e-cigarettes is from
Note added July 18, 2016:  A reader named Jason Artman read the above post and brought my attention to his website, where he is maintaining a comprehensive list of over 100 e-cigarette explosion incidents.  

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