Black Dusty residue

We live in the Seattle area in a stick built home from 1994. Our heating system is forced heat, natural gas. All the homes in this area get a black residue build-up all along the edges of the carpet and it is not cleanable. I have now noticed that a similar residue is forming on any white plastic in the house. It is forming inside cabinets and in drawers. The furnace was inspected, serviced, and cleaned just 1 month ago. Does anyone know what the residue is and is it harmful? Is there anyway to prevent it from forming? It is making anything light in color and plastic look very dirty.

Thanks, Rachel

 

Sounds like mold to me, and the bad kind. Get a mold specialist in there to take a look. Your health may depend on it.