Hello PizzaArtMan, Welcome to the club. As unappetizingly sounding as coal-fired baking may appear to be, as far as exposing product to potential carcinogens, it may actually be less hazardous than wood, that is to say, because of the extremely high heat of a coal-fired oven, remarkably fast baking time, there is briefer exposure time; not to mention a separate firebox. Further, since at least the sixties, New York City code has specified only the burning of anthracite coal in pizza ovens (probably what had been the preferred fuel for coal-fired bakery ovens anyway). Anthracite is high carbon, low sulphur, virtually smokeless and productive of extremely high temperatures. I've no especial knowledge regarding the origin of the coal-fired oven. The story I heard was that coal was simply less expensive than firewood in metropolitain New York of the late nineteenth century - possibly imaginable in a still largely steam-powered world at the dawn of the twentieth century.