Which rocket fuel? There's so many different ones. Methalox engines produce water vapor. Kerolox engines use refined kerosene, so lots of soot and your regular

Which rocket fuel? There's so many different ones. Methalox engines produce water vapor. Kerolox engines use refined kerosene, so lots of soot and your regular fossil fuel combustion byproducts. And then there's the hypergols, which are indeed, incredibly toxic.