Is it safe to keep hand sanitizer in a hot car?

As lockdown restrictions during the time of COVID-19 start easing up in much of the country, people have gradually started venturing out more. With that means practicing the most effective measures to reduce the risk of contracting or spreading the disease, such as maintaining social distancing, wearing face masks and washing hands with soap and water.

Since not everyone has access to soap and water when they are on the go, many resort to using the next best option: hand sanitizer. Many people keep hand sanitizer readily available in their cars, as it is an important safety measure to keep hands clean during the pandemic. The United States Centers for Disease Control and Prevention (CDC) recommends using alcohol-based hand sanitizer that contains at least 60 percent alcohol when soap and water are not readily available.

In a recent viral social media post, a fire department in Wisconsin posted on Facebook warning about the dangers of keeping hand sanitizer in a car during a hot day. The post included a photo, which was originally taken in Brazil, of a burned car door as a result of keeping hand sanitizer near an open flame in a car.

The now-deleted statement from the fire department explained that since most hand sanitizer is alcohol-based, it is flammable. Therefore, keeping it in a car during hot weather can expose it to the sun, which could potentially cause it to combust. More particularly, they said it is important not to keep it near an open flame like those of cigarettes or grills.

The Facebook post raises the question of whether it is safe to leave hand sanitizer in your car on a hot day, and if so, for how long.

Jason McKnight, MD, family medicine physician at Texas A&M Health Family Care and clinical assistant professor at the Texas A&M College of Medicine, explains that there is no real danger in keeping hand sanitizer in your car on a hot day.

“As far as combustibility of hand sanitizer, I think that’s a non-issue,” McKnight said. “If you look at what they call the auto-combustion temperature of ethyl alcohol or isopropyl alcohol, which are the two that are most commonly in hand sanitizers, those are 600- and 700-degrees Fahrenheit. Even in the middle of the summer, your car is never going to get to that point where that’s going to be a concern.”

According to the National Fire Protection Association, the hand sanitizer would indeed have to reach up to 700 degrees Fahrenheit for it to catch fire without the presence of a flame or spark.

There are concerns that heat and direct sunlight can degrade some of the ingredients in the hand sanitizer, causing the hand sanitizer to be less effective, but it really depends on the content of the hand sanitizer, according to McKnight.

“Long-term heat, long-term sun exposure can always degrade some kinds of chemicals, but I think that’s more of an issue if it’s in direct sunlight and for a prolonged period of time,” McKnight said. “If you’re using a hand sanitizer fairly regularly and keeping it in a shaded area of the car, somewhere that’s not in direct sunlight, I don’t think you’re going to have much of an issue with that.”

The incidence of fires is rare when it comes to alcohol-based hand sanitizers, but the CDC does recommend that hand sanitizer be stored safely to avoid any possible issues of concern. It should also be kept away from any open flames, as all alcohol products are potentially flammable.

In general, it is best to store hand sanitizer in a cool, dry environment away from direct sunlight. If left in the car, it is best to leave it in the door or in the console of a car or in any place sunlight will not directly hit the hand sanitizer.

“I keep hand sanitizer in a safe spot in my vehicle currently,” McKnight said. “It can sometimes be a good way to remind you to actually use sanitizer because anytime you get in a car, grab it and use it. Unless you’ve been at home, you have most definitely come in contact with some surfaces that may very well have some kind of pathogenic bacteria or virus on it, and so having it in your vehicle and remembering when you get in to use it is a good memory tool.”