Alcohol-Based Hand Sanitizers and Fire Safety

In light of the COVID-19 healthcare crisis, the Center for Disease Control (CDC) recommends washing hands with soap and water for 20 seconds; especially after going to the bathroom, before eating, and after coughing, sneezing, or blowing your nose.  But if soap and water are not available, the CDC recommends using an alcohol-based hand sanitizer (AHBS) with at least 60% alcohol can help you avoid getting sick and spreading germs to others.

Most ABHS products contain a high volume of alcohol, which is the reason ABHSs could be a fire hazard if not stored properly and used as directed. ABHSs contains ethyl alcohol, which readily evaporates at room temperature into an ignitable vapor and is therefore classified as Class I Flammable Liquid, which means they have a flashpoint of less than 100 degrees Fahrenheit. Keeping a bottle in your bag or at home or the occasional use will not cause a sudden conflagration and the general use of ABHSs pose a low risk from a fire hazard standpoint. 

One of the most common questions Fire Prevention Services receives, is can you leave ABHSs in your car?  It is safe to leave ABHS in your car, although it probably isn't the best place for storage, especially in hot Texas summers.  Earlier this year the Western Lakes Fire District (WLFD) in Oconomowoc, Wisconsin posted on its Facebook page, “By its nature, most hand sanitizer is alcohol-based and therefore flammable," the WLFD wrote. "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.”

The problem is people seemed to misunderstand the definition of the flashpoint of ABHSs, which is around 63 degrees Fahrenheit.  The flashpoint, a technical term used to characterize the propensity of a liquid to burn, is being confused with ignition temperature. The flashpoint is the minimum temperature of a liquid at which sufficient vapor is given off to form an ignitable mixture with the air - but those vapors still need to be met with an ignition source to catch fire.

After ABHSs have exposed to temperatures above their flash point and vapors are given off, you eventually still have to generate enough heat from an ignition source, (e.g., open flame or an electrical spark) to be able to ignite the vapors.  The ignition temperature of the alcohol in the sanitizer is between 680 to 700 degrees.  The ignition temperature of a substance is the least temperature at which the substance starts combustion.  For comparison, paper burns at 451 degrees Fahrenheit and a butane lighter flame burns around 3000 degrees. So, without a flame present there can be no fire.  Studies show a vehicle sitting in the scorching summer sun won’t get above 200 degrees Fahrenheit.  Therefore the risk of explosion when leaving ABHSs in a hot car, is very unlikely to occur and not a major cause for concern.

Although leaving ABHSs in the car is relatively safe, over time, the alcohol content in ABHSs will evaporate and make it less effective.  This process speeds up at high temperatures for an extended period of time.  However, as long as the container is closed, you should be able to leave it in your car temporarily.  Keeping the cap, pump, or lid tightly sealed in a car will not speed up the evaporation process.