spaceSpace and Physics

"Spontaneous Combustion" Fires In Austin Triggered By Nothing Less Than Humble Tortilla Chips


Robin Andrews

Science & Policy Writer

Whoops. Austin Fire Department via Facebook

Sometimes, stories just write themselves. Take it away, whoever runs the Austin Fire Department’s Facebook account:

“Tortilla chips are big business around these parts. We take them seriously,” the post – spotted by – begins, noting how vital they are for dipping into things. “So imagine how distressed we were to be called to a fire at a tortilla chip factory earlier this week…not once, but twice!”


These weren’t ordinary fires though. It seems that at a storage facility of some kind, their team were called to put out a conflagration of the chips triggered by spontaneous combustion. “Yes, you read that right,” the post adds. “Spontaneous combustion. Of tortilla chips.”

Three days later, another few boxes of the chips – technically waste pellets from the chip's manufacturing – also spontaneously burst into flames. In order to stop this madness, the team “drowned all of the other crates that had yet to burn, thereby eliminating the risk completely.”


Now, spontaneous combustion is one of those terms that has a bit of a loaded meaning. Don’t deny it: When you first saw the term, what came to mind were those tales of people just bursting into flames for no apparent reason, often leading to a fatality.

Although there is plenty of anecdotes surrounding the unexpected, abrupt, fiery deaths of people, there’s essentially no solid evidence that demonstrates it’s possible. Instead, those cases were probably caused by something else; a nearby fire, say, created by a dropped cigarette during a snooze.


In any case, there is some interesting, gruesome science as to why people burn, well, non-uniformly that you can read about here.

It’s fair to say that the spontaneous combustion of other things is scientifically sound, though. It still requires the right kinds of materials and environmental conditions for an ignition event to occur, but it can, and it has.

As spotted by Gizmodo, a Centers for Disease Control and Prevention (CDC)-funded study explained that coal is a great example of this. Famously flammable already, it turns out that if there’s enough oxygen in its presence and a not-frigid temperature, it begins to react with it and oxidize.

Combustion, whether it involves complete or a messier, incomplete chemical path, is a more extreme oxidation process. That means that if the heat generated by the coal’s slow oxidation can’t go anywhere, a feedback cycle begins: the more heat, the more the coal oxidizes, which generates more heat. That can lead to an inexorable path towards ignition, which is in itself “spontaneous”.


In fact, the aforementioned article contains some bizarre and sometimes counterintuitive inclusions, like especially wet hay being prone to bursting into flames. All involve the presence of free oxygen in the (dry) air to varying degrees.

It’s not clear yet why the tortilla chips spontaneously combusted, but this digital pamphlet by the South Australian Metropolitan Fire Service offers some clues. It mentions that various oils are potentially vulnerable to self-heating when in the right environment. These include linseed, rapeseed, peanut, corn, fish, cottonseed, and safflower oils.

As it happens, safflower, peanut, and cottonseed oils – among others – are often used in the high heat frying of corn tortilla chips. Perhaps, then, they’re the fire starters in this incident, which the Austin Fire Department blame on the factory's new way of handling the chip waste.

In case you were wondering: Yes, your bag of tortilla chips in your house is perfectly safe in this regard. They won’t suddenly burst into flames and kill you, so please feel free to eat and dip and munch away to your heart’s content.


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