Understanding Firewood Mold

Whether you’re hanging out beside the bonfire, roasting marshmallows in your backyard or enjoying the crackling warmth of a campfire at the lake; firewood is a critical ingredient in making fond memories. However, not all firewood is created equal, and moldy firewood can taint your fun faster than you can say “health hazard”. So, let’s explore the “how” and “why” of mold growing on firewood, the risks of burning wood with mold growth, and some storage techniques to help prevent mold growing on your firewood in the first place.

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Why Does Mold Grow on Firewood?

Mold is a type of fungus that thrives in moist, warm environments and needs organic material to grow and thrive. Firewood, being organic matter, provides an ideal food source for mold growth when the conditions are right. Here are a few reasons why mold might grow on your firewood:

• Moisture: Firewood that isn't properly dried or is stored in a damp environment is susceptible to mold growth. Moisture is the primary factor that promotes mold development.

• Lack of Air Circulation: Storing firewood in a poorly ventilated area can trap moisture, creating a perfect environment for mold.

• Temperature: Warm temperatures can accelerate mold growth. When combined with moisture, firewood can become moldy very quickly.

It’s important to know that it’s completely normal for you to find a bit of mold on your firewood, especially when it’s outdoors, since that’s a part of the natural process of breaking down wood. However, when that moldy wood is used for your campfires, it can make you sick, and if you subsequently store it inside, the mold can spread from the firewood to other parts of your home.

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What Are The Health Risks of Burning Moldy Firewood?

Burning moldy firewood releases mold spores and other harmful particles into the air. Inhaling these particles can be detrimental to health, particularly for certain groups of people including those with asthma, who are immunocompromised, or are very young or very old. Here’s how it can impact health:

• Respiratory Issues: Inhaling mold spores irritates the lungs, causing inflammation. In a healthy person, this can cause coughing, sneezing, a sore throat and even difficulty breathing. In a very old or very young person, or somebody with asthma, this can trigger a medical emergency if the airway swells shut and the person cannot breathe.

• Allergic Reactions: People who have environmental allergies, for example to dust, pet dander, pollen etc., are at higher risk of complications and more severe symptoms from exposure to mold spores. Mold exposure in people with underlying conditions and mold allergies can result in severe symptoms like wheezing, shortness of breath and chest tightness and could turn into a medical emergency.  

• Mold Toxicity: Some molds are considered toxic. They produce mycotoxins which can produce more than just symptoms of respiratory irritation from inhaling spores. Exposure to mycotoxins can cause issues like headaches, dizziness, fatigue, nosebleeds, fever, vomiting and more! 

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Can You Use Firewood with Mold on it for Cooking?

You shouldn’t burn moldy firewood at all, but cooking over moldy firewood is especially dangerous. Not only will you be exposing yourself to airborne mold spores, but you’re putting yourself at risk of ingesting them in your food. Ingesting food contaminated by mold spores can lead to food-borne illness and distressing symptoms including (but not limited to) nausea, vomiting, and other gastro-intestinal issues. 

How to Store Firewood Properly

Proper firewood storage (which prevents mold growth) is essential to your health and safety.

Can I Store Firewood Indoors?

Storing firewood indoors may seem convenient, especially in the winter when the weather turns, but it should be avoided at all costs. Storing firewood indoors can actually increase the risk of mold growth because indoor environments retain moisture - especially your basement and garage; which are popular indoor firewood storage spots. Not only can indoor moisture levels impact the likelihood of mold growth, but mold can spread from your firewood to surrounding structures in your home, and firewood can harbour insects and pests you don’t want to infest your home either.

To minimize these risks, only bring in as much firewood as you intend to use. Ensure the wood is dry and free from pests before bringing it inside! 

How to Properly Store Firewood Outdoors

Proper outdoor storage is essential to ensuring firewood stays dry, mold-, and pest-free.

• Elevate the Wood: Don’t store your firewood on the ground. Store it up off the ground on a rack or a pallet to prevent moisture from seeping in from the ground. 

• Cover the Wood: Use a waterproof cover like a tarp, or build a roof over the top of your firewood pile to protect the wood from rain and snow. The cover should not drape over the sides (if using a tarp) or otherwise enclose the sides (if building a structure) because that can trap moisture and impede air flow!

• Ensure Proper Ventilation: Stack your firewood in such a way that air can circulate throughout the stack freely. Proper ventilation helps the wood dry out and helps prevent mold growth. 

• Sunlight: Store your firewood in a sunny spot if at all possible. Direct sunlight will help keep your firewood dry and keep mold from growing. 

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Keep your family warm and safe this winter by committing to proper firewood storage practices today. Wishing you all a happy, healthy night beside the fire.