Accidental fires are one of the single biggest dangers you can encounter whether you are at home or out in the field. Or even in your own backyard!
If you’ve ever been at a cookout and seeking relief from remorseless mosquitoes and biting flies, you probably reached for a can of bug spray.
But, is there any possibility that your bug spray might endanger you and others if used too close to the grill or the tiki torches? Is bug spray flammable?
Yes, most bug spray formulations are highly flammable. One of the most common bug sprays, DEET, has a flashpoint between 275°F and 324°F and is highly prone to ignition in its aerosol form.
Bug spray, like so many pressurized chemicals used in aerosol cans, is highly prone to ignition. Not only the propellant is flammable but the bug spray chemical itself tends to be quite the accelerant.
Naturally, this can be seriously bad news if you are a smoker or using it too close to flames, sparks or any other hot surfaces. Considering how ubiquitous this stuff is, you better get serious about fire safety with it.
Keep reading and I’ll tell you what you need to know…
Is Bug Spray Combustible?
Yes, bug spray is highly combustible. This means that it has the ability to catch fire and burn when it comes into contact with a heat source or flame.
According to Occupational Safety and Health Administration (OSHA) standards, a liquid is considered combustible if it has a flash point at or above 100°F, but below 200°F.
Bug sprays, especially those containing DEET, or diethyltoluamide, fall under this category.
Does Bug Spray Ignite at Any Temperature?
Yes, it can and will! However, it does have a specific range of temperatures at which it can ignite depending on the formula.
Bug sprays that are formulated with DEET, one of the most common and effective ingredients, usually ignite with a flashpoint of between 275° F and 324°F.
This relatively low flash point demands that common bug sprays be handled, applied and stored with caution!
Does Bug Spray React with High Temperature?
Yes, bug spray can react negatively to high temperatures. The active ingredients in bug sprays, usually DEET or sometimes permethrin, can undergo various chemical reactions if subjected to prolonged high temperatures, even those that will not result in ignition.
For instance, the toxicity of these substances may increase due to the acceleration of certain chemical reactions at higher temperatures.
Additionally, high temperatures can lead to evaporation of some components, altering the concentration and efficacy of the bug spray. These changes can potentially increase the health risks associated with exposure to these substances.
You should store bug sprays in cool, well-ventilated areas away from direct sunlight or heat sources to prevent unintended outcomes like this.
Different Bug Spray Formulations Have Different Flash Points
I should note that there are numerous formulas for bug sprays commonly available in the United States and globally. DEET is the most common but not the only one!
These different formulations can all have varying flash points, which is the again the minimum temperature at which the solution can ignite.
A given spray’s flashpoint depends almost totally on the concentration and type of ingredients used in the spray. Thus, you would be wise to not assume a universal flash point for all bug spray.
I highly advise you to read the info on the can or the manufacturer’s safety data sheet to figure out the specific flash point and safety measures for each product.
Warning: Aerosol Bug Spray Cans Can Dangerously Combust if Sprayed on Ignition Source!
Aerosol bug sprays expel tiny, fine particles through a nozzle via a propellant gas.
When these particles come into contact with an ignition source such as a flame or spark, they can ignite even more rapidly than usual due to their large surface area, often flammable propellant and the increased oxygen present in the spray mixture.
This rapid ignition can create a “trail” of fire that can travel up the stream and potentially reach the aerosol reservoir in the can itself. If the flame penetrates the can, it can cause the pressure inside the can to increase dramatically and almost instantly.
This sudden increase in internal pressure will cause the can to rupture, releasing the remaining contents and fragments of metal in a violent burst. Therefore, it’s critical that you never, ever use aerosol bug sprays near open flames or any other potential ignition sources.
Is Bug Spray Flammable When Dry?
Possibly. Most of these flammable chemicals don’t become non-flammable because they dry!
The flammability of bug spray when dry largely depends on its chemical composition. While it’s true that bug spray is generally less flammable when it dries, certain ingredients may still pose a fire risk.
For example, some bug sprays contain alcohol or hydrocarbons, both of which are highly flammable substances. If these ingredients have not completely evaporated after the bug spray has dried, they could still ignite if exposed to a flame or spark.
Also, the active ingredients used in many bug sprays, like DEET or permethrin, retain their flammability even when dry. Don’t assume there’s no fire danger because your sprayed skin or clothing is dry to the touch!
Is All-Natural Bug Spray Flammable?
Yes, as a rule of thumb. While all-natural bug sprays are free from the synthetic chemicals we’ve talked about, they will invariably have alcohol (as a solvent) and other volatile substances that can easily ignite and sustain a fire.
Natural ingredients like essential oils are also known to be flammable: the high volatility of these components means they can evaporate quickly, creating a combustible vapor-air mixture in the presence of an ignition source.
Despite being natural, treat these bug sprays the same as your would the normal lab-made stuff. They should be used with caution around flames or sparks to prevent accidental fires!
Will Bug Spray Make a Fire Worse?
Oh yes, definitely! Introducing bug spray in any form to an existing fire is highly likely to intensify the situation.
All of the ingredients in bug spray, both active and inactive ingredients, can act as effective accelerants causing the fire to spread more rapidly and burn more intensely.
Particularly aerosolized bug spray can create a wide, flammable mist that can catch fire and easily spread a fire or ignite nearby combustible materials like an impromptu flamethrower!
For this reason, always remember safety first when applying or carrying bug spray!
Is Bug Spray Reactive with Other Substances?
Most bug sprays, particularly those containing DEET, can react negatively with certain substances.
For instance, DEET is known to react with certain plastics and synthetic fabrics, causing them to become discolored or even dissolve! This is because DEET has solvent properties that can break down certain types of plastics.
Bug spray can also interact with other chemicals: for example, when combined with sunscreen, DEET’s effectiveness can be reduced. DEET can negatively react with certain medications like anti-histamines and create toxic byproducts.
Be aware of these interactions when using bug spray, and take the time to read all of the warning statements on the package before you commit to using it!
How Should You Deal with Bug Spray Exposed to Fire?
When you have to put out a fire involving bug spray, the best course of action is simply to use a fire extinguisher that discharges dry chemical agent, foam, or carbon dioxide.
These types, known as Class B extinguishers, are good at putting out fires caused by flammable liquids- like bug spray.
Water may not be effective depending on the exact formulation of the bug spray, as water can sometimes spread these flammable liquids rather than extinguishing them.
Smothering the fire might work, but it can be more dangerous and difficult to accomplish safely.
If you have one, a common ABC-rated fire extinguisher, which is designed for multiple fire types including those involving flammable liquids, is an ideal choice in such situations.
Tom Marlowe practically grew up with a gun in his hand, and has held all kinds of jobs in the gun industry: range safety, sales, instruction and consulting, Tom has the experience to help civilian shooters figure out what will work best for them.