Sorry I could not begin to make a guess what this is. In the past one would have put it under a microscope to see if any recognisable structures were present, failing that, then try and see what would grow in culture and proceed from there. These days molecular methods would probably be the first step?
I think a taxonomist with knowledge of this type of fungus only is required - but I put it into CNM not with the idea of precisely identifying it but reminding people of what is in arborist wood chips. I also should have added that this type of fungus can produce a lot of spores which are breathable.