Also be careful if you cut steel then plastic then back to steel, bag type extraction systems will catch fire. This happened to us twice, we had to change to a wet extraction system. That said our old 2KW Amada LC Alpha used to handle up to 6mm polycarbonate, softer nylon type plastics were a bit of a no no, they just melted.
I would repeat the warning over what is in the fumes, when I was much younger we had a sub contractor cutting some plastic for us on night shift, they came in in the morning and the operator was passed out on the floor overcome by fumes.