So how does the asbestos get into your floor or ceiling?

People have to work with it and those people are not hazmat wearing highly paid specialists but your normal workers who get the burden of making sure that they take all precautions during their whole working career no matter the environmental conditions. And the only support they get from their employer are probably just the mask and a note to always use it.

Disclaimer: I have an asbestos linked death in my immediate family so my opinion may be biased.