So the title says it all. If I am scavenging wood in the wilderness, does some of it burn toxic? If so what kinds. This question is derived from this answer.
Yes, some sources create toxic smoke/fumes, notably:
- Poison Ivy (smoke can cause lung damage in some cases)
I'm not sure of a comprehensive list, but be wary of any poisonous wood / shrub, it's probably more likely to burn toxic. As pointed out in the comment, unless you can identify vines well then it may be a good idea to stay away from all of them - dead ones are hard to identify.
In addition, be aware that any wood containing sap (pine for instance) will tend to spit, so don't cook directly on such a fire, otherwise your food may get coated! These are generally OK to use if your food is well above the fire though.
I also wouldn't use any processed wood that may contain glue, varnish etc. - highly likely it could burn toxic. I know this is for a survival situation, but sometimes you can come across "easy" treated wood that's been dumped off someone (old furniture for instance.) I wouldn't just immediately grab it, especially if you're using it for cooking.
At The Wood Database is a table of 235 wood types—intended for woodworkers—which indicates the irritation reactions, type of irritations (skin, eyes, respiratory), and irritation potency. It should be helpful to infer which woods might be poor choices to burn and breathe.
For example, Douglas-fir irritates all three areas but at low potency. Reactions include irritant, giddiness, runny nose, splinters go septic, nausea. The details say that reactions to Doug-fir are quite uncommon.
At the other extreme is Australian Cashew Nut which causes irritant, skin lesions, nosebleeds of maximum potency. Surprisingly, Western Red Cedar has the same severe irritation ratings (and I love sawing it up and deeply inhaling the aroma).
Sumac is a known toxic burning wood of North America. You are not to use it with the preparation of food.
As noted in a comment, all wood can be considered to release toxins in the smoke when burned. You may be exposed to more toxic smoke if you burn hotter fires.
Wood contains a lot of chemicals, and burning it involves a lot of chemical reactions. Different chemicals burn off into the smoke at different temperatures.
I do not smoke food, but my understanding of food smoking is that lower temperature smoke is better for smoking meat.
I have read that more toxic chemicals tend to smoke out at much higher temperatures, approaching or exceeding 1000 degrees F (540 C). This is especially relevant to those using home-made wood charcoal, as the chemicals which burn at lower temp are already driven off, so you are more likely to be burning a hotter fire with less pleasant smoke. Likely less smoke overall, but that smoke may be made of more toxic chemicals.
I have made some good quality charcoal and plan to try some crafts next year such as pottery, melting down steel, or making some glass; these require very high temperatures (please use extreme caution and do your research if you follow suit). When I recently found out that late-stage smoke may be more toxic, that was concerning to me. If I do these projects, I will need to avoid the smoke as much as possible.
I recall a few articles which discuss the higher-temp toxic smokes, but I do not remember how to get at them now. I will update this answer within a day or two after I track down the reference links.
There is nothing wrong with burning rhododendron, as long as it is seasiond, it burns hot and fast, so you will need a large pile or mix with other longer burning logs, it's tangled nature makes it sometimes difficult to harvest, it's is commonly burned in areas where it is plentyfull and invasive. In green wood, it has traces of toxin however when dried it is quite safe to burn