While the flash point of hand sanitizer is low, you still need an ignition source to start a fire, almost impossible even in a hot car on a sunny day in the middle of a desert.
Western Lakes Fire District, a fire fighting station based out of Wisconsin, is receiving a lot of negative backlash for a photo of a burned interior door they shared, WLFD claiming that this results from a bottle of alcohol-based hand sanitizer. While, given the right conditions, a bottle of hand sanitizer could facilitate a car fire, the chances of all those conditions coming together are close to nil or impossible. This is, in other words, fake news.
Here’s their post below and here’s why they’re 100 percent wrong.
The first red-flag is the source of this photo, the Wisconsin Fire Department doesn’t give a source and even local news couldn’t confirm where this image even came from.
Alcohol-based hand sanitizer contains, most commonly 70 percent ethanol or isopropyl for its disinfecting properties. Popular alcoholic drinks also contain similar levels of alcohol, images and videos of alcohol on fire at bars further fueling this fear-inducing practice of hand sanitizers in cars.
The auto-ignition temperature, or the temperature alcohol-based liquids spontaneously combust without an ignition source, is around 700F so you don’t have to worry about hand sanitizer in a glove box.
However, alcohol-based hand sanitizer is flammable with a low-flash point of around 70 degrees F. The flash point is the lowest temperature where vapors ignite if given an ignition source. Note, while car interiors regular go above 70 F, you still need an ignition source like a match or flame for vapors to catch fire.
This Wisconsin fire department points out that, because of the magnification effect of water in bottles, light energy can concentrate enough on a single spot to cause a fire. While it’s true that bottles of water CAN cause fires in cars, the conditions have to be just right for it to work.
Notice when you look up ‘water bottles catching fire in cars’ it’s the sun hitting a water bottle on its curved, convex shape at the rounded top of a bottle at the right angle that causes this. While water has a magnifying effect, it’s the curved, convex, lens-like shape of the water bottle that really focuses light energy. Most bottles of hand sanitizer do not have this perfectly convex-shaped lens near its top.Embed from Getty Images
For a bottle of hand sanitizer to catch on fire you’d have to place the bottle of hand sanitizer at just the right angle to catch the sun rays, concentrating light on that one convex-shaped area, if there even is one. Then you have to ensure that the sun doesn’t move, which is not possible because the earth rotates and all.
The National Fire Protection Association gives guidelines for storing hand sanitizer but only if you exceed five gallons in any one place.
Consider that, since this current crisis and long before this, even when hand sanitizer first became popular in the early 1980s, zero cars have caught fire because of a hand sanitizer bottle left out.
After all this scientific evidence, if you’re still freaked out about the possibility, just stick the stuff in your glove box or in your center console away from the sun.
For the rest of us rationale humans, no, hand sanitizer left in your car will not catch fire.