The Truth About Hand Sanitizer Exploding In Your Car

Phone, wallet, keys. And hand sanitizer; these are the things we take with us, no matter where we go during the pandemic (oh, and a face mask!). If you leave a bottle of hand sanitizer in your car, you aren't alone. After all, that way, this potentially life-saving product is always on hand (pun intended). But according to Yahoo, a lot of people believe that as summer months draw near and with rising temperatures, a hot car is an unsafe place to keep hand sanitizer. It could explode, or, because it contains alcohol — at least 60 percent if you're using the kind that is effective at killing the COVID-19 virus — the hot car could heat the product to the point of the alcohol burning off. Then, your bottle would be more or less useless. Well, maybe not.

"The active ingredient in there is alcohol," confirms Dr. William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine. Here's the thing: Although Schaffner admits some alcohol burns off when a substance is heated, your car would literally need to reach over 173 degrees to boil your hand sanitizer to the point of the alcohol burning off significantly enough to matter.

Your car would have to get really, really (really) hot

Ethanol alcohol (the kind that's in hand sani) has a boiling point of 173 degrees according to Encyclopedia Britannica. Even if you live in Southern Florida, summer temps are unlikely to heat the inside of your car to that level, although, it's not completely out of the realm of possibility. Schaffner says you'd know if your bottle of hand sanitizer had been exposed to such extreme heat (some experts say the temperature would have to be closer to 500 to 700 degrees for it to matter) since the cap would pop off, and the bottle itself might be melted.

So your hand sanitizer exploding, boiling to the point of ineffectiveness, or otherwise creating a huge problem if left in the car isn't likely. But leaving a product that contains alcohol in your hot car isn't the best idea, especially since experts remind us alcohol is by nature flammable. 

Still, don't believe everything you see and hear. 

Hand sanitizer best practices

When a Wisconsin fire department posted a video of a car's door being burned after hand sanitizer was left inside, people understandably freaked out (via News 3 Las Vegas). But the video was later taken down. Michael Pravica, a professor of physics at the University of Nevada, Las Vegas says hand sanitizer starting a fire isn't likely at all. "I would just be more worried about somebody trying to open the top like a pop bottle and then suddenly, all this alcohol splashing in your eye," he explains about the pressure that can build up inside the bottle on a hot day.

But that doesn't mean Pravica is recommending people leave hand sanitizer in the car. "It might not be a bad idea just to take the hand sanitizer with you," he says, even if the danger of a hand sani explosion or fire are very, very, very low or even mostly impossible.