Have you ever seen asbestos in it's original form? It's pretty neat. It's a mineral but you can shred it apart. I guess that's part of the reason it was so effective in decades past as a fire inhibitor. It's kind of hard to burn a rock, let alone to spread a fire with a stone. It seemed a simple yet effective solution to reducing the effects of a building fire as well as containing excess heat such as from a furnace when coal was around, prior to oil and gas conversions. The furnace in my house growing up had an asbestos wrapper around it. I remember what a mess it made when a piece would flake off and you'd have top put a cement patch in it's place. They were always dusty too, on the surface that is. I also remember when the oil man came to replace the old furnace with a new oil fired one and took the old one away to the dump. No such thing today! Hazmat trained personnel have to be hired and precautions put in place for full biohazard containment. That dust I remember led many people down a dark road of despair, enduring malignant Mesothelioma treatment, if they were lucky enough to be diagnosed early enough. My father in law was one such person affected by asbestos and in turn contracting Mesothelioma, eventually leading to his untimely demise. He got it from being a fireman, entering burning structures full of asbestos. Asbestos was in flooring, ceiling tiles, pipe insulation, furnace insulation, water heater insulation, the list go on and on. Did I also mention that this is one of the many reasons why fireman where breathing devices in burning structures? It is. That's why! It's not just the smoke but also what might be hiding in the smoke as well.