I read the poplular mechanics page from the link, shyam sunder states ""When you have a significant portion of a floor collapsing, it's going to shoot air and concrete dust out the window," he forgot to mention that there were also multi-ton wall units and steel beams flying our horizontally at over 50mph. To be able to generate ungodly huge clouds of concrete dust, just by crushing, come on. Is there any way through testing that anyone could get a concrete block to turn into a cloud of dust? There is no way you can crush it that would cause that.

The best site in my opinion to give to people about the collapse is csi911 dot info because it makes a great scientific case that the collapse/crush scenario could never generate the force need to hurl wall units out of the building and create the immense clouds of dust, among many other characteristics of the event.