Does Heat or Fire Kill Mold? What You Need to Know

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Mold can be a wonderful thing, ask any cheesemaker, but for most of us? It’s not something we want to find on our walls, our food, or any other item in our homes. It can be incredibly destructive, it smells bad and it can be very, very unpleasant for our health and wellbeing. Which often leads people to wonder whether they might use heat or flames to tackle a mold problem?

Yes, heat will kill most types of mold if the temperature high enough for long enough (160 degrees Fahrenheit or 70 degrees Celsius). While the heat from a fire could theoretically kill mold, it is not a good idea to use fire for this purpose, as it can be very dangerous.

Let’s look more at mold and how it behaves when heated, as well as what can happen if you used fire to try to kill mold. Here’s what you need to know about mold and fire. 

Your # 1 priority is keeping your family safe. As a firefighter, I recommend everyone has updated smoke detectors that don’t require battery changes, like these ones from Kidde, a fire extinguisher, like this one from Amerex, and a fire escape ladder if you have bedrooms above the first floor, I recommend this one from Hausse.

Also read: Does Fire Kill Germs/Bacteria/Viruses?

What Is Mold?

heat or fire kills mold

Mold (called “mould” in many countries outside the US) is a group of fungi that can grow in multi-cellular filaments.

A fungus that grows in a single-celled filament is known as a “yeast” by contrast. 

There are quite literally thousands of fungal species that qualify as “mold”, but they all tend to result in the discoloration of the things they grow on and, in the case of food, also to present a sort of fuzzy or fluffy exterior. 

They can cause huge damage to anything from food to property, but they can also be beneficial in the creation of some foods, beverages, antibiotics, medicines, enzymes, and biotechnology. 

It is possible for a human being to be allergic to mold or to get sick from pathogenic molds which, once inside the body, are happy to grow on or in their new human host. 

Some molds are safe to eat, but many are toxic and can result in sickness or even death if consumed in any quantity. 

One famous form of toxic mold is that which grows on rye bread. It can lead to a condition called ergotism when consumed – initially, the effect is similar to a hallucinogen, but eventually, it leads to madness and even painful death. 

Why Is Mold Bad?

Not all mold is bad.

If mold is bad for a human being it’s because it is either toxic when inhaled (usually in the form of spores) or because it’s toxic when eaten.

Mold may also be considered “bad” if it grows on something and damages it, particularly if that something was intended for further use. 

It is impossible to mold-proof the world as mold spores are present in the air around us at all times. 

Does Heat Kill Mold?

Yes, mainly. It’s important to note that there are some molds that have evolved a certain level of heat resistance, but most molds can be killed by heat.

They begin to break down at a cellular level (as do many other biological organisms) once the heat threshold (about 160 degrees Fahrenheit or 70 Celsius) rises enough. 

Also read: How Hot Is A Lighter Flame?

Can Mold Survive High Heat?

Some few molds have adapted to resist high heat, however, this doesn’t mean that somewhere out there lurks a super-mold that can withstand any heat. Eventually, under high heat, all molds will break down and die. 

It is worth noting though that while molds die in high temperatures, they aren’t destroyed by them, there will still be dead mold present on the thing that has been heated. 

This is something to bear in mind if you were thinking of cooking something that has gone moldy, not only will the mold still be there if you were to eat, but so will any of the toxins that it produced when before it died. 

Therefore, cooking is not the solution to mold contamination of food.

We’d also urge caution in “cutting mold off” food before cooking it – the toxins molds produce may still be present in other parts of the food and mold spores may also be present on the rest of the food but not enough to be visible to the naked eye. 

You can see why this isn’t a good idea in this video:

How To Use Heat To Kill Mold?

The idea is to raise the temperature of the item to 160 degrees Fahrenheit or above and for a period of time long enough that the mold is completely destroyed – around twenty minutes should suffice. 

You can do this with fabric, for example, by using a tumble dryer. On some household items, it might be sensible to place them in the dishwasher to obtain this kind of heat or place them in the oven.

It’s worth noting that not every moldy item can be rescued, and it may be the most sensible plan to simply throw out and replace it. 

Once you’ve eliminated the mold, you should go back and wash the item thoroughly to try and remove any traces of dead mold and toxins. 

Does Fire Kill Mold?

Yes, of course, fire kills mold in the same way extreme heat kills molds.

However, we would strongly urge you never to use fire on molds in any circumstances as it can be extremely hazardous to your health. 

What Does Fire Do To Mold? 

The reason is that when you apply a flame to a mold, it goes into survival mode. The mold is aware (at a genetic level, molds don’t appear to have the equivalent of a “brain”) that it has very little time to live when a flame is introduced and thus, it begins to release spores in huge quantities hoping to pass its genes on to the next generation of molds.

This is a sensible plan for the mold, but bad news for those of us thinking we might burn off some mold.

Fungal spores are bad news for our health in a lot of cases. And the odds are very good that we’re going to breathe some in during burning or that we might see those spores float into our neighbor’s garden for them to breathe in. 

Even if the spores aren’t toxic, they can trigger asthma and other respiratory conditions in the vulnerable and may also irritate eyes and airways. In some cases, the person inhaling the spores might also have an allergic reaction to them.

Can Mold Be Burned?

Yes, but as we’ve seen burning mold is a risky business. It’s better to heat treat molds rather than to burn them in the vast majority of cases.

If you were to burn mold, the best way to do this would be to go somewhere remote and wear breathing equipment and sealed safety spectacles while starting the fire and then to remove yourself to a good distance away to minimize potential exposure to spores.

Given this, we really cannot recommend a strategy of using fire to deal with mold at all. 

Also read: Does Smoke And Fire Repel Mosquitoes?

What Temp Does Mold Die?

Your molds will die at around 160-170 degrees Fahrenheit (70 degrees Celsius).

That’s not a very hot temperature (it’s about the same heat as a cup of tea or coffee when first poured). 

That means assuming the moldy substance is not highly flammable or combustible, it shouldn’t be too challenging to be able to heat treat with heat without requiring a flame. 

For more info about how to kill mold, watch this video:

Can You Burn Wood With Fungus? 

Obviously, you can burn moldy wood but burning wood with fungus is a bad idea. If you’re foraging for firewood, then it’s best to leave firewood with fungi on it alone – avoid sick trees and check the wood for mushrooms or unusual colors. 

Try to keep your firewood pile to a minimum and only stock a few days at a time and use it all completely before replacing it – this should keep new mold growth to a minimum too. 

If you notice black mold on anything including firewood – do not burn it in any circumstances it might be a toxic mold called Stachybotrys chartarum and there is no easy way to distinguish this mold from other black molds. 

What Do I Do With Moldy Firewood? Can Moldy Firewood Be Saved?

You may be able to treat your firewood for mold using the following method:

  • Place the firewood in a neat pile in direct sunlight
  • Stack it properly as soon as it is cut, in single rows of a single log’s thickness
  • Let it dry for 6 months (1 year if it is dense wood)
  • Then brush off the mold before you bring it in to burn (wear a mask while you do this). 


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