Article about reason/excuses for pat downs.
http://www.latimes.com/news/nationworld/nation/la-na-petn-20101124,0,3675872.story
It begins:
New airport security procedures that have stirred the emotions of air travelers — full-body scans and aggressive pat-downs — were largely designed to detect an explosive powder called PETN, which has been a staple of Al Qaeda bomb makers for nearly a decade.