True, but there's a difference in toxicity between wood and plastic. And the glue used for multiplex is more towards plastic than wood when it comes to how harmful it is. But there's also wood which is harmful. Like figs trees, they are also very toxic when burned. Just be careful with what you burn. A regular campfire or stove fire with stuff like birch or other common woods isn't that bad unless you're highly sensitive, like astma, but stuff like plastic, glue, or other chemicals should not be burned and it's fumes definitely not inhalated.