Re: nice story
For "clicker" substitute "clinker", which is a congealed residue from burning coal that contains more impurities, like sodium, potassium and calcium. It typically forms sponge-like lumps that can have sharp edges when cool. As far as I know, such clinker is no more toxic than the coal it came from, and may be less so.
Fly Ash is quite different, resulting from the burning of crushed coal. Coal is crushed to enable more complete burning, but the residue of this is typically a very fine ash that can cause significant health issues when breathed in, and can form dangerous slurries if wet. The ash, like clinker, forms with sharp edges but because it starts so small the individual particles are small enough to do real damage in the air and in water, being very abrasive. Properly disposing of Fly Ash is very necessary.
As for radioactivity - well Carbon has several common isotopes anc the process of burning will often result in some localised concentrates forming. It is not significantly more dangerous than being in an area with granite bedrock.
Biting the hand that feeds IT
