During the COVID-19 Pandemic people have become accustomed to having bottle of hand sanitizer on them at all times. As the warmer weather begins, you may want to watch where you leave your sanitizer.

The National Fire Prevention Association released a video that discusses the flammability of the different types of alcohol used in gel hand sanitizers. Guy Colonna Senior is the Director of Technical Services for NFPA. He appeared in the video to talk about the "flash points" for ethanol and isopropanol alcohols, the most commonly used in hand sanitizers.

A "flash point" is the point at which a flammable liquid gives off enough vapor to ignite in the air. Colonna says the flash point for these alcohol based hand sanitizer is only about 63-70 degrees Fahrenheit. That means a bottle of hand sanitizer can give off a flammable vapor inside its bottle sitting in a hot car on a sunny hot day.

Colonna says, "The materials you're talking about, either ethanol or isopropanol, are the two most common alcohols that are part of these alcohol-based hand rubs do have a flashpoint of about 60-70 degrees Fahrenheit." He continues, "Consequently that puts them right at about room temperature, which means they don't need an external heat source to cause them to actually give off those vapors." He adds that once the combination of vapors and oxygen mix, all that is needed to cause a problem is a viable ignition source.

That source of ignition could be the flick of a lighter or cigarette. But, under extreme heat and pressure, the liquid inside the bottle could be dangerous. Storing hand sanitizer in large quantities increases the risk. The NFPA says anything over 5 gallons needs to be stored in proper places such as a flammable materials cabinet or in an area with an active functioning sprinkler system.

Anecdotally, leaving a small bottle of the liquid hand sanitizer in a hot car can lead to problems. In my personal experience I had a very small amount left in a mini-bottle. After a long time sitting in the sun in my vehicle cup-holder I popped the top to apply some to my hands and the liquid spewed everywhere, most likely due to those vapors getting beyond their flash-point and being under pressure (the closed bottle).

Again, the NFPA states that it's highly unlikely a bottle of hand sanitizer would spontaneously combust without some sort of external ignition source, but it's important to be conscious of the risks involved with materials most are relying on to keep them safe during the current health crisis.

The Western Lakes Fire Department in Wisconsin 'sparked' controversy with a Facebook post featuring a singed door, warning people of the risks of hand sanitizer. It stated,

Let’s start today with a little education!

We’ve chatted in the past about clear water bottles being kept in your vehicle when the weather is warm.

That still holds true and so does hand sanitizer! By its nature, most hand sanitizer is alcohol-based and therefore flammable. Keeping it in your car during hot weather, exposing it to sun causing magnification of light through the bottle,
----and particularly being next to open flame while smoking in vehicles or grilling while enjoying this weekend----can lead to disaster.

Please respect the possibilities and be fire safe.

While the validity of the photo in the Facebook post from the fire department can't be verified, we were more interested in the video from the National Fire Protection Association.

The important thing to remember is that the vapor formed by the alcohol inside the hand sanitizer gel when heated to a temperature above 60-70 degrees Fahrenheit could be flammable. Try to avoid storing your hand sanitizer in high temperatures and in direct sunlight. You are of course encouraged to still use it frequently to kill germs and help stop the spread of disease.

MORE INFO: 7 easy ways to stop touching your face

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