Almost all of the furnishings used in a house give off fumes that are every bit as toxic as the nonmetallic conduit fumes. In my opinion, in most types of buildings, the toxic fumes given off by burning building materials are so much less than those given off by the burning contents and furnishings in the structure that the fumes from nonmetallic conduit or plumbing piping are almost insignificant. By the way, wool produces cyanide gas when it burns.
Don
