With hand sanitizer now a common part of people’s hand hygiene routine due to the coronavirus, the Honolulu Fire Department has a warning–hand sanitizer is flammable.

The key germ fighting ingredient is alcohol.

“It is technically a Class 1 flammable liquid, which means that at room temperature, it is readily ignitable,” Honolulu Fire Captain Jeffrey Roache explained.

So what exactly does that mean? Do you need to be worried?

“Worried? No. Cautious? Yes,” Captain Roache said.

Captain Roache said hand sanitizer can catch fire if it’s exposed to an ignition source like an open flame.

“Let’s say someone smokes and they put on hand sanitizer. They smoke while they’re driving, put it on, and light it up that could definitely ignite,” Captain Roache said.

In order to prevent that from happening, Captain Roache said it is important to make sure your hands are completely dry after using hand sanitizer before being remotely close to an ignition source like a barbecue.

Online, there are posts about hand sanitizer bottles exploding and starting fires in cars. So is that true?

“Technically, it would be true, but in order for that to happen, for it to spontaneously combust, the temperatures in the car would need to reach near 700 degrees Fahrenheit,” Captain Roache said.

Captain Roache said it is highly unlikely that a hand sanitizer bottle would explode and start a fire in a car.

The Queen’s Medical Center Infection Preventionist Michael Schweikert said the bigger concern is leaving hand stanitizer in the car and it essentially becoming useless.

“If it’s exposed to heat, the alcohol is evaporating, so the product itself is losing its effectiveness,” Schweikert said. “It’s not a perfect seal, so the gas and vapors will eventually seep from the cap, if it’s closed.”

Schweikert said if you are going to leave hand sanitizer in your car, make sure it is not in direct sunlight. The glove compartment or underneath the seat would be the best spots.