AARON BROWN: The scope of this continues to boggle the mind at various points. We know, because Tom Ridge said and though it had been reported a lot, that the anthrax spores that ended up in the Daschle letter and in the Daschle office were very small. And very small in this case is very dangerous. And just to show you how dangerous it can be, we asked CNN medical correspondent Sanjay Gupta to set up a little experiment, and here's how it played out.</s>DR. SANJAY GUPTA, CNN CORRESPONDENT (on camera): In order to demonstrate how a powdery substance may have gotten out of an envelope, we took some standard talcum powder and a standard envelope and sealed it in a standard fashion. Now look, with just a little bit of pressure on the envelope you can see quite a bit of the powder actually getting through. That's just with some gentle tapping. Typically an envelope like this would actually find its way in a post office, and eventually through a mail sorter. Now what's really remarkable here is that this powder is getting not just through the sides of the envelope, but actually through the paper of the envelope itself. Why is that? The porous size of some paper is typically of about 100 microns. That means the actual pores are about 100 microns in size. That's the thickness of a strand of hair. The powder is about 30 to 40 microns in size, less than half. And the bacterial anthrax spores that we've been hearing so much about that cause inhalational anthrax are typically one to five microns in size. You can't see them. They're too small to be seen by the naked eye. Is this how the powdery substance might have gotten out of an envelope and contaminated a postal office? We don't know. But it is a possibility. Dr. Sanjay Gupta, CNN, Atlanta.</s>BROWN: We certainly know it could have gotten there that way.
Talcum Powder Escapes Sealed Envelope