bone and tissue fragments

Reporter collected WTC dust on 9/11; recent lab analysis is an eye-opener!

Mike McAuliff collected a sample of the WTC dust on 9/11/2001, and a few weeks ago sent it to a lab for analysis.

He writes:  "very fine fragments of photographs, fingernails, bones, hair, and tissue."  What Mike does not ask is: What agent reduced human bone, fingernails, and tissue to very fine fragments (as he notes from lab reports)? Will pancaking floors have this effect -- if so how?  It seems to me that pancaking floors would tend to trap bones, not fragment them as explosives would do.  Centimeter-long human bone fragments were found on the roof of the Deutsche Bank building, about 200 meters (or yards) away from the WTC complex.  What force splintered human bone and hurled it hundreds of yards?  Are not these observations evidence for the use of explosives?  I hesitate to speak in scientific terms of of such a sensitive matter, but victims' relatives (including Bob McIlvaine) have asked that I, as a Professor of Physics, speak out on these issues.