Billy
I would suggest that the public officials that you mentioned are no better informed about this matter then you or other members of the forum.
I suggest that you look at this link, as these people actually HAVE an informed opinion after doing the research.

A report from Oak Ridge
National Labs.

"Will Duct Tape and Plastic Really Work?"
Issues Related To Expedient Shelter-In-Place
John H. Sorensen, Barbara M. Vogt
August 2001
http://emc.ornl.gov/EMC/PDF/TM_2001_154_duct_plastic.pdf

Jeff