Microwaves/anthrax/physics

[Chuck Cooper <ccc@pp.pdx.edu>]

I answered a query about using a home microwave to kill anthrax on mail,

below is my response. I would like a second opinion on the second

paragraph if anyone has one.





================================

Microwaves heat by exciting water molecules specifically. So unless the

spore contains a significant amount of water, you will not raise the

spore temperature much using microwaves. I would guess that spores

contain very little water or don't need it to remain viable. They are

able to survive in harsh arid environments for decades. A water molecule

is so small that it would be able to diffuse through the spore capsule

under these conditions.



Another more fundamental and obscure problem is the spore volume to

surface area ratio. In the micron size realm of a spore the internal

volume of a sphere is very small in relation to its surface area. So

small that it radiates internal heat to the surrounding cooler

environment of the microwave very efficiently. So you really can't heat

individual spores (or loose aggregations) that might be present on dry

paper with a microwave enough to kill them.



So, a microwave is NOT an effective way to kill spores on mail and may

be dangerous to your mail, your microwave and hence to you.



(any metallic foil and some inks can heat in a microwave enough to cause

a fire)



************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.