This question does not cross the minds of many campers, because of their excitement for one of the sweetest virtues of their next camping trip: the Bonfire. But to ensure the safety of all campers involved, this question needs to be addressed at length.
The following types of wood are toxic and should be avoided:
- Poison sumac
- Edible Fig Trees
- Black Cherry
- Chinese Laquer
- Camphor Tree
- Many ornamental trees
- Pressure-treated wood
- Particle Board
- Stained wood
While most campers do not come across many complications when it comes to firewood, this question is an important one to consider for those with special health concerns. There are materials that should be avoided when making a fire for the benefit of all those present.
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Types of Toxic Wood
Smoke from burning wood, whatever the type, is not good to inhale (see below), but some wood smoke is genuinely toxic and can cause rapid damage to your lungs. The following is a non-comprehensive list of wood that when burned can cause damage to eyes, skin, and your lungs:
Poison sumac is even more deadly than poison oak and ivy, especially when burned. According to Wikipedia:
In the worst case, smoke inhaled by burning poison sumac leads to life-threatening pulmonary edema whereby fluid enters the alveoli.Wikipedia
Poison Sumac looks like a small tree, and the leaves are in groups of 7-13 on one twig. The leaves are also directly opposite from each other and they also have a shiny smooth texture. For pictures check out WebMD.
There’s some dispute on the toxicity of actually burning fig trees, but there is no doubt at all that the leaves and sap of the common edible fig tree are extremely poisonous. (source)
It could be that if the fig tree has completely dried out that it isn’t as toxic (or it could be that when burned that the toxic stuff could be gone). In any case, I’m not taking my chances. Skip burning fig tree wood.
Black Cherry (Wild Cherry)
Black Cherry seems like it would be non-dangerous but is actually toxic, and according to Victor Lewitus in an article entitled called Poisonous Plants, says that it’s especially dangerous when burned.
You can see more information about Black Cherry here.
Chinese Lacquer tree
Another non-native tree that’s a popular ornamental is extremely poisonous and dangerous to burn. The smoke is known to cause an allergic reaction. (source)
This tree is native to East Asia but now can be found in the United States and all over the world. Although it’s not as toxic as other trees camphor is harvested from the bark and is considered toxic (source) and is probably better to skip burning this where you might inhale the smoke (such as a campfire).
Trees In Your Backyard (Ornamental Trees)
If you live in the United States, you are fortunate that many common tree species are relatively safe to burn. However, you may have not thought about this–but your backyard trees may actually be pretty dangerous.
For example the Bat’s Wing Coral Tree is native to Australia and has toxic leaves, fruit, and bark (and if you didn’t know, just about all plants and animals native to Australia are dangerous).
If you’re in the U.S., you might think–cool! I don’t have to worry about it!
The problem is that we buy trees from all over the world from our local nurseries. The Bat’s Wing Coral Tree is just one example of something you’d find at a nursery.
Another example is the yew tree. You see these trees all the time and they’re beautiful–but remember that ornamental trees are around for their looks and not for their practicallity or safety.
So, although many trees are beautiful, unfortunately, many are quite dangerous to burn. If you don’t know what type of tree it is, be on the safe side and don’t burn ornamental trees.
According to the EPA, driftwood releases toxic or harmful chemicals when burned. MotherEarthNews states that burning driftwood releases Dioxin, which is an emission that doesn’t decompose in our bloodstream.
Plywood is created by gluing several very thin pieces of wood together creating a super strong layer of wood. Plywood is an incredible invention, but the glue in the manufacturing process is toxic.
Plywood manufacturers often use urea formaldehyde (source).
Urea formaldehyde fume symptoms can bring on the following symptoms according to Wikipedia:
[…] watery eyes, nose irritations, wheezing and coughing, fatigue, skin rash, severe allergic reactions, burning sensations in the eyes and throat, nausea, and difficulty in breathing in some humanssource
Pressure-treated wood is wood that has been injected with preservative chemicals at high pressures so they are more resistent to decay. Home Depot states that one chemical used commonly in pressure-treated wood is alkaline copper quaternary.
According to the EPA, the fumes created during the pressure treatment releases arsenic and other chemicals in the air.
Wood stain is made from a binder, a pigment, and a solvent, with the solvent sometimes being mineral spirits, and the binder made from linseed oil.
Some sources like this one state that mineral spirits inhalation can cause breathing difficulty–I am not sure if it would matter if the stain has been dried on wood for a long time.
What’s more likely is that the wood itself has been treated in some other way so it will resist mold and last longer.
Particle board is basically wood chips glued together. They are often glued using urea formaldehyde, the same chemical used to make plywood which has these symptoms I talk about earlier.
Wood that could be completely safe to burn can be a different story if the wood is rotten.
Part of what makes wood rot is fungus and mold–the wood deteriorates quickly as microbes get energy from the decomposing wood.
Furthermore, rotten wood often can get spongy and absorb and retain water, making it poor firewood in any case.
The interent says that fungus and mold can be released while burning which would be dangerous to inhale. As far as what I’ve been able to research I haven’t found any conclusive evidence of someone getting sick from burning moldy wood.
Poisonous Vines (Poison Oak and Poison Ivy)
Generally, you aren’t going to be burning vines, but if you are adding kindling with a bunch of brush, you need to be careful not to drag poison oak or ivy into the flames. Also, some poison ivy/oak climb up trees so they could be surrounding the wood you’re burning. Lastly, some can even look more like a shrub than a vine.
Remember, poison ivy and poison oak have leaves in groups of 3. The leaves can be shiny or dusty depending on the variety.
In fact, when it comes down to it, you’re better off not burning groups of weeds or soft non-grasses. You’d be amazed at how many poisonous plants are out there. For example, we have this weed called “Noseburn” in our backyard, and when you touch it your skin blisters in less than a minute.
My son and I have both found that out the hard way. Don’t burn weeds if you can help it.
Which Other Types of Firewood Should I Avoid Burning?
Besides woods and plants that are toxic, themselves, there are some other things to be aware of:
- If you’re camping, don’t bring non-native wood (wood from 20-30 miles around the area). In fact, some parks are very strict on this point and will only allow wood that they provide to be burned. Travelling firewood can bring pests to new areas therefore spreading disease or other issues. (One example of this is the Bark Beetle, which is incredibly destructive and has destroyed 10s of millions of acres of forest)
- According to the EPA, materials like driftwood, plywood, cardboard, pressure-treated wood, rotten/moldy wood, and anything that is covered by a poisonous material (glue, plastic, rubber, asbestos, animal remains, and certain plant matter) are off-limits for burning.
- Some wood pallets (source) are treated with a preservative and are therefore unsafe to be burned. Furthermore, pallets leave behind nails and that’s not something you want to leave behind in the firepit.
Avoid Fresh Wood
One rule of thumb is to avoid burning fresh wood. If you are burning newly cut wood you are risking burning any accompanying vines, or the leaves themselves. Also, when the wood is fresh it has moisture and any accompanying toxins. Even if there were toxins in the wood and leaves, if the wood has been dead for over 6 months it should be safe to use.
You probably aren’t a botanist and you probably won’t know every type of wood you are burning. You lower your risk factor a lot by waiting for your wood to dry out (can take 6 months or more) before burning.
I recently saw a little girl’s face that was red and swollen from an allergic reaction due to burning a pile of fresh wood. It’s impossible to know which exact tree that caused it–in any case, you run many more risks if you are burning freshly felled trees.
Besides the risk of toxins, fresh wood puts off so much more smoke and doesn’t burn very well–which isn’t very fun at all to be around.
Which Types of Firewood Are Safe To Burn?
The best wood to burn for a campfire is one that is not living, wood that is locally available, non-driftwood, non-poisonous, and is presently dry.
Oak, beech, elm, and cedar trees make for good firewood. Pine can smoke a lot and has a lot of sap, which isn’t a concern in a campfire but should be avoided for a fireplace (to avoid buildup of burned sap inside the chimney)
Most common and native dried hard and softwoods that you run into in the forests of Northern America will be safe to burn. But the key is that you should try to only burn dried wood.
Firewood is commonly broken down into two categories: hardwood and softwood. Hardwood is much denser than softwood, so they burn slower, hotter, and more intensely. This wood is best for creating a long-lasting fire for cooking; after, of course, the fire has been built up by softwood. Softwood is much easier to light than hardwoods, and they burn quicker with more smoke; perfect for starting a bonfire. Virtually all of the most common hardwood and softwood trees in North America are safe to burn.
One thing to note is that it’s only relatively safe. Inhaling wood smoke has its own negative effects even if they aren’t toxic.
If you’re going camping, the easiest thing to do is just buy the firewood that’s at the campground. Many parks want you to use local wood, anyway, and this is an easy way for you to not have to worry about it.
Is Burning Rotten Wood Unsafe?
Rotten wood is full of moisture as it soaks up the water from the atmosphere and the ground around it. This will create a buildup of mold, and this is not something you want floating around by the food you are trying to cook. If only the outside of the wood is damp, but the heartwood inside is nice and dry, you may consider using this in your fire. If the whole piece of wood is soaked, then it is probably best to find a different piece of wood. Using drier wood is better for the life of your next fire as well as the lives of the people sitting around it.
What Wood is Toxic for Cooking?
Truthfully, there are a few strange species that you should not cook over, and I have included a link to a site with complete details on all of those different species down below in “Possible Side Effects”. There are not many risks with most of the common types of trees around North America. When we are trying to smoke or cook meat, hardwood is the best bet.
Hardwoods such as Oak, Hickory, Maple, Pecan, and Cherry are all fantastic types to use if you can get your hands on them, but you shouldn’t worry too much about any toxic buildup on your food. I would advise, however, that you stray from using most pine trees to cook with because the sap will get on the food and create a sticky texture.
If you would like some helpful starter information about cooking over a fire, we laid it all out and talked about lots of helpful tools and some caveats, you should check out our post about cooking over a fire if you’d like to know more.
If you have trouble getting the fire started, I actually use a couple of gadgets I think are really cool. You can check out what I like to use here.
Is Wood Smoke Toxic?
Burning things such as Sumac, Oleander, Rhododendron, and Poison Ivy are all known to create toxic smoke and in some cases even cause lung damage. These are obviously not good materials to be burning in your next fire, but there also comes a risk from burning regular types of wood.
According to the Department of Ecology of the State of Washington, “Wood smoke contains tiny particles and gases that can have serious health effects when breathed…Much like cigarette smoke, wood smoke contains hundreds of air pollutants that can cause cancer and other health problems”.
Additionally, the EPA states that inhaling any kind of wood smoke increases your risk of lung infection.
When you have to burn wood, make sure you use the driest wood available. Living wood is prone to releasing much more smoke into the air, so stay away from greenwood. Also make sure to keep the fire burning hot by giving the fire room to “breathe”, or exposing it to more oxygen. Low-temperature fires will tend to not burn as well and actually create a higher level of smoke as they die down.
Possible Side Effects
For a complete list of the health concerns when it comes to choosing the right wood for your fire, feel free to check out this useful site. For now, here is a list of the possible complications with burning unknown wood:
- Nervous System Effects
- Nose Bleeds
- Pink Eye
- Excessive Thirst
- Swelling Skins
- Stomach Cramps
Types of Hardwood:
Oak: These trees are extremely common in North America. All oak trees can be identified as such if they have acorns, lobed leaves that have rounded or pointed knobs extending out from their centers, and small, scaly pieces of bark that looks like the back of a reptile.
Birch: These trees are naturally found in cooler, northern climates, and they all are easily identified by their paper-thin peeling bark that is normally a mix of white, silver, and black. Their leaves are usually 2-3 inches long and are oval-shaped with saw-toothed edges.
Ash: Ash trees are easily mistaken for other types of hardwood trees, (which are all excellent for a slow cooking fire) such as black walnut, hickory, and elm. Ash trees have an “opposite branching arrangement” in their branches, meaning that the branches on both sides of the tree are directly across from each other.
If a branch has fallen off, check for a bud where the branch should have been. Ash trees also have distinctive “compound leaves” with 5-11 leaflets per compound. This means that 5-11 leaves come off of a single stem. Lastly, these trees have a diamond-shaped pattern bark that tends to be gray-brown.
Types of Softwood:
Cedar: Western Red Cedars have reddish-brown bark with vertical ridges up the tree, and cones that are reddish as well. Their leaves grow in pairs at a 90-degree angle, so that it creates a flat-looking structure. These trees are found mostly in the Pacific Northwest at a lower elevation.
Pine: These trees obviously have needles instead of leaves, and these needles grow in clusters in either 2s, 3s, or 5s. They are also home to hard and thick cones, as opposed to other conifers that have flaky feeling cones.
Larch: These trees prefer the colder climates of high mountains and in the Northern parts of North America. They are one the only coniferous trees to lose their needles in the fall, and they can be identified by their needle cluster and single cone combination per shoot.
When it comes to building a fire at your next campsite, whether it’s for heat, cooking, or simply for social reasons, make sure to create it inside of a prepared fire pit. Most campsites have these set up for you, but at some primitive sites you might have to create one by building one by making a small circle of rocks away from anything flammable.
Even the type of rocks you choose for your fire could be dangerous! Rocks actually explode! It’s a well-documented phenomenon. If you want to learn which rocks are safe to use for a campfire, check out our post here.
Most sites will have collections of wood ready for you to use, but be prepared to scavenge for more scrapes of dry wood if necessary. Take some time to study the types of hardwood and softwood trees that were listed out so that in a pinch you can gather the best wood for your next adventure.