As we head into the summer months and our thermometer readings tick higher and higher, we all know the discomfort involved with getting into a sweltering vehicle that's been sitting in the sun. Under such circumstances, interior car temperatures can climb to over 150 degrees Fahrenheit. It's certainly unsafe to leave a person or a pet inside a vehicle that hot, but what about a bottle of hand sanitizer? After all, alcohol-based hand sanitizers are considered flammable liquids.
Despite some information currently being released on social media and in the news, the short answer is no. From a fire safety standpoint, it is not unsafe to leave hand sanitizer inside a hot vehicle. Here's why.
Flashpoint does not equal ignition temperature
While it's true that most hand sanitizers have a flashpoint around room temperature, that doesn't mean the liquid will all of a sudden catch fire if it reaches that temperature. Flashpoint is a technical term used to characterize the propensity of a liquid to burn. It defines the temperature at which a liquid gives off enough vapor to become ignitible in the air. At that temperature, however, you still need an ignition source like a flame from a candle or a lighter for ignition to occur.
This point became muddled through a recent news story from Wisconsin. A fire department there publicly shared an image from an incident that reportedly occurred in Brazil, showing a burned car door after hand sanitizer being stored in the vehicle was exposed to a flame. Many erroneously interpreted the department's warning as saying hand sanitizer can spontaneously ignite inside a hot car, which is untrue. "Simply be careful and realize that a product we all use very frequently can be dangerous if it contacts open flame of any kind, but specifically cigarettes or those from grills," the department clarified.
Spontaneous ignition, on the other hand, involves a substance self-heating to a point where it ignites, without the need for any outside ignition source like a flame. Hand sanitizer is not subject to self-heating and would require temperatures to reach over 700 degrees Fahrenheit to spontaneously ignite, according to Guy Colonna, director of Technical Services at NFPA.
"Spontaneous ignition would be an ignition source independent of a flame or a spark, [and] it requires a material that is reactive to do what's called self-heat," Colonna says in a new video interview on the topic (above). "Internally, it undergoes a reaction and changes its properties, and when changing its properties, it releases lots of heat energy. Hand sanitizer, the alcohol [in it], is a material not inclined to do that. ... The ignition temperature of the alcohols are going to be something in excess of 700 degrees Fahrenheit."
In other words, while hand sanitizer gives off ignitable vapors at roughly room temperature or above, that vapor-air mixture still needs to be exposed to very high temperatures to ignite. A flame can do it. A hot car can't.
Still a fire hazard
All of this said, hand sanitizer still presents fire safety concerns, especially when stored in bulk quantities. For any storage amount over 5 gallons, NFPA 30, Flammable and Combustible Liquids Code, would apply. That was the message included in a Learn Something New (LSN) video released last month.
"What we're seeing during [the coronavirus] pandemic is a lot of hand sanitizer being stored in places you might expect, like hospitals, but also in places that haven't traditionally stored such liquids," I say in the video. "A Tennessee man, for example, made headlines in March for having stockpiled almost 18,000 bottles of hand sanitizer." In doing so, Colonna says in the video, these individuals or companies may be compromising safety, if protection systems designed to protect the storage of such quantities of flammable liquids are not in place.
Watch the full LSN video here.