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Picture of Moldy Firewood

Should I Worry About Burning Moldy Firewood?

This is a question that one of my friends asked me recently. Having had some experience with the mold removal industry, it is not uncommon for me to receive these types of questions. However, I found this particular question more interesting than most, because there are so many different variables and additional dangers. So I thought I would take time to delve deep into this subject matter to address all the issues that can and will arise from moldy firewood.

Putting this Question in Context

Providing context for this question is particularly important in this particular instance. So here is what prompted my friend to ask me the question. He lives in Georgia where a wood burning fireplace is pretty common. It was February and the temperature had dropped down to the mid 30’s. What better time is there for staying in and enjoying a movie by a fire? He usually uses a firewood delivery company but it was a weekend and knew there would be no way to get a delivery the same day. So he jaunted to the a local grocery store (a large chain whose name I will not mention for legal purposes, but it rhymes with Ogre). He wandered up and down the aisles before finding the firewood between the predictably placed credit union and the over the counter medicine aisles. He stood there visually analyzing the bags of firewood to determine which ones had the largest size and volume before lumbering one of the bags into his shopping cart. Upon closer inspection he noticed what appeared to be dirt on the outside of all the orange mesh bags. This is firewood, it came from outside, a little dirt is to be expected. He picked up the first bag of firewood and noticed a smoke like green dust wafting through the air. He then realized that what he had been staring at on the outside of the firewood bags was not dirt at all, it was mold. Copious amounts of mold. The smoke like green dust as he described it, was actually a large number of mold spores that had been dispersed into the air.

Why the Firewood had Mold Growth

The firewood had come into the store wet which could have been due to lack of proper drying in a kiln, insufficient protection from the elements where it was stored, or it was simply rained upon when it was being delivered to the store. Regardless of how the firewood got wet, it was now on the interior of the store and the firewood had everything it needed for mold to flourish. The mold spores were already on the wood but were simply lacking the right environment. Mold spores are all around us each day, and mold actually has a fundamental role in nature’s decomposition process. The fact that there were mold spores on the wood is no big surprise.

The only thing mold needs to thrive and reproduce, is water (Relative humidity over 50%), a food source (any organic material, in this case wood) and a dark environment deprived of light. The wood was stacked in a manner that allowed a vast majority of the wood to be unexposed to the light. The bags on the top of the pile were shielding the bags below from exposure to light.

Increasing Probability of Exposure to Toxic Mold Spores

  • Exposure In-Store

    The fact that the mold contaminated firewood was located inside of a grocery store, compounds the level of danger exponentially. The wet & spore ridden wood was brought into the store where the humidity levels were significantly lower than outside. As mold runs out of water, it senses the end of its life-cycle and increases spore production. Whenever, a bag of wood was picked up by a customer, the coarse mesh material, rubs against the other mold filled bags causing vast quantities of mold spores to be released. Even the air flow caused by someone walking by the wood is enough to dislodge mold spores making them airborne. Most people also place their bags of firewood in shopping carts which contaminates the shopping carts with mold spores. Additionally, as the wood-filled cart gets pushed through the store, the air flow will cause mold spores to be spread throughout the store. The produce department is particularly troublesome in this equation. The produce department in a grocery store is a mold spore’s dream come true. The produce has a regular water source (produce misters), organic matter for food (fruit and vegetables), and darkness (the areas below the fruit and vegetables). The mold spores within the store will be able to rest upon fruit and vegetables in the store and even be ingested if the produce is not washed thoroughly.

  • Exposure at Home

    First and foremost, bringing moldy firewood into your home is a mistake. There is no way of telling what type of mold is growing on the wood unless it is tested. Bringing the mold contaminated wood into your home guarantees that you will be spreading mold spores throughout your home. The mold on the wood could be toxic Stachybotrys Chartarum (black mold) or another type of toxic mold such as Aspergillus. If you do bring the firewood into your home and decide to burn it you will be dispersing spores rapidly throughout your home. When a fire is burning, although the smoke may travel up the fireplace flue, air will circulate from inside the fireplace to outside of the fireplace. When a fire is burning, it causes rapid air movement which will dislodge spores and spread them throughout your home.

Mold Experts Agree

Mold experts all agree that knowingly exposing your home to mold spores in any scenario is never a good idea. Just because you have mold spores in your home, does not mean you will immediately have toxic mold growing in your home. The mold spores can survive harsh conditions over long period of time. Spores just wait to be exposed to the right environment where they can thrive and multiply rapidly.

Summing up the Story

Unfortunately, my friend bought the firewood anyway and brought it home. That is when he sent me a picture of the firewood with the question. I found myself wanting to scold him like a child who did something they knew they were not supposed to do “what were you thinking?” So to answer the question, should you burn wood with visible mold on it? No! It is never worth the risk. Mold removal can be expensive and most homeowners insurance companies will not cover the cost of mold removal.