Fire extinguishers are a feature in many homes, yet lately, you’ve wondered if that necessarily makes the extinguisher safe to use. Is the stuff that comes out of a fire extinguisher toxic?
Fire extinguishers that contain dry powder are generally not toxic but can be irritating. If the powder gets on your skin, you could experience itchiness and redness. Breathing in the powder can lead to a sore throat and an upset stomach.
If you still have questions about the potential toxicity of fire extinguishers, you’ve come to the right place. Ahead, we’ll explain everything you need to know about what’s in a fire extinguisher and what ill effects it can cause, so keep reading!
What’s in a Fire Extinguisher?
Not all fire extinguishers are the same. They’re rated A, B, C, D, or K.
Class A fire extinguishers are for putting out solid combustible fires. Class B fire extinguishers can put out fires from flammable gases and liquids, Class C extinguishers fires from electrical equipment, Class D extinguishers fires from combustible metals, and Class K fire extinguishers can put out fires from fats and oils.
Depending on the type of fire extinguisher, when you use it, different substances will come out. Here’s an overview.
If a fire requires the displacement of oxygen to extinguish it, then a fire extinguisher might include gaseous agents known as halons. The most popular types of halons used in fire extinguishers are Halon 1211 and Halon 1301.
You’ll only see halons as the extinguishing agent in Class B and Class C fire extinguishers.
For Class D fires, some fire extinguishers might release plain water, usually via a mist, air-pressurized water, or water from a pump.
Much more often though, fire extinguishers will use water additives, wet chemicals, or wetting agents. These products can extinguish Class A and Class K fires.
Non-aspirated and aspirated foams will choke off the fire’s oxygen supply and prevent the fire from continuing to burn.
Aqueous film-forming foam is common for Class A and Class B fires. If a fire has a type of alcohol as the fuel source, then a fire extinguisher containing alcohol-resistant aqueous film-forming foam is needed.
The compressed air foam system is yet another fire extinguisher option. This system releases foam at a rate over 140 pounds per square inch of pressure or PSI and can put out Class A and Class B fires.
If not a foam, water additive, or halon, then a fire extinguisher will release a dry powder.
The most common powder ingredient is monoammonium phosphate, which is nicknamed the ABC dry chemical due to its suitability for Class A, Class B, and Class C fires.
Monoammonium phosphate has a pale yellow hue and is known for being rather corrosive.
If not monoammonium phosphate, then potassium bicarbonate powder will be released from a fire extinguisher, especially for Class B and Class C.
The effectiveness of potassium bicarbonate on Class B fires makes it a top choice for fire extinguishers.
The third ingredient that might be used to make fire extinguisher powder is sodium bicarbonate. This was one of the original dry chemicals. When used on Class B or Class C fires, sodium bicarbonate releases carbon dioxide that will smother a fire.
That said, potassium bicarbonate works better on Class B fires than sodium bicarbonate.
Are Fire Extinguishers Toxic?
You’ll recall that most household fire extinguishers are ABC or monoammonium phosphate extinguishers.
You know only about monoammonium phosphate what you read in the last section, but you want to know more. Is the stuff toxic to ingest or be exposed to?
No, monoammonium phosphate is not toxic. You have to think about it from the perspective of the manufacturers. They know that, even when used properly, a firefighter operating a fire extinguisher could be exposed to the powder inside.
If the powder was lethal, that would not only be risky to the firefighter, but the fire department as well as any civilians in a burning building that need rescuing. They’d have to worry not only about the smoke but the monoammonium phosphate as well.
Risks of Fire Extinguisher Powder Exposure
Bearing that in mind, just because monoammonium phosphate and other fire extinguisher powders aren’t toxic doesn’t mean that exposure can’t be dangerous.
You’ll recall from earlier that monoammonium phosphate is corrosive, so it’s not something you want lingering on bare skin.
You could develop redness and itchiness where the powder was. The effects should be temporary, especially if you’re fast to remove the fire extinguisher powder residue.
You should also take precautions not to inhale the stuff. Breathing in monoammonium phosphate can agitate the upper respiratory tract both because it’s a corrosive substance and because you’re breathing in a dust-like powder.
You might begin coughing, and your throat could start burning. If you breathed in enough of the substance, then monoammonium phosphate exposure could even lead to an upset stomach.
All said, the health risks of exposure to monoammonium sulfate are not that severe and should not cause permanent damage.
You might have a scratchy throat, reddened skin, and some nausea, but all should pass once you breathe in fresher air and wash off any powdery residue.
Fire extinguishers may be full of foam, water additives, halons, or dry powder. Of the powders used, monoammonium phosphate is the one you’ll come across the most often.
While monoammonium phosphate is not toxic, it is irritating on the skin and respiratory tract (and your stomach), so try to limit exposure as much as you can.
Should you be exposed to monoammonium phosphate, move away from the area, and clean any residue off your skin.