some chemistry occurs as a result of burning. dependent on substance it can be worse, or more immediate. e.g. benomyl [fungicide] https://en.wikipedia.org/wiki

some chemistry occurs as a result of burning. dependent on substance it can be worse, or more immediate. e.g. benomyl [fungicide] https://en.wikipedia.org/wiki/Benomyl https://en.wikipedia.org/wiki/Benomyl will produce cyanide as combustion product.