The story you read sounds as though it were found in a sensational red
top,
professional gardeners still recommend the use of leached soot and leached
ash.

Mary

I can't remember where I read it now. I guess it makes sense if it is left
out in the rain to allow the noxious salts to leach out before it is used on
the garden. The problem only exists with coal ash/soot and not wood ash/soot
of course. Coal can contain all manner of toxic minerals including arsenic,
mercury, cadmium etc

David.