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RE: Dirty bomb article (Nature)
Hi All,
Having spent 10 years in an aerosol science environment at the
old Lovelace ITRI, I am aware of all your points. However, that is
not the main aim of my comment. My main point of attack was the fact
that the physicists quoted did not take the basic facts of aerosol
science into account and their support sounds to me like a knee jerk
reaction. There was no indication that they were aware of any points
in your answer.
Your answer sounds a little bit like an agreement with the trend
of the article but the fact is that we don't know anything about the
aerosols involved. Being honest, we therefore have to say that we just
don't know how dangerous the aerosolized portion of a dirty bomb would
be.
Best
Fritz
*****************************************************
Fritz A. Seiler, Ph.D.
Sigma Five Consulting: Private:
P.O. Box 1709 P.O. Box 437
Los Lunas, NM 87031 Tome', NM 87060
Tel.: 505-866-5193 Tel. 505-866-6976
Fax: 505-866-5197 USA
*****************************************************
-----Original Message-----
From: owner-radsafe@list.Vanderbilt.Edu
[mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of Wright, Will
(DHS-PSB)
Sent: Wednesday, May 05, 2004 4:55 PM
To: Fritz A. Seiler; radsafe@list.Vanderbilt.Edu; Bjorn Cedervall
Cc: Joseph L. Alvarez
Subject: RE: Dirty bomb article (Nature)
you are correct regarding the behavior of the particle at 100(some pollen)
which by definition is not an aerosol as well as the 10 u which is an
aerosol. however, they are both readily inhalable and 10 remains perhaps
suspended for some time, but they differ in that the 100 is easily removed
through clearance mechanisms because they get no further than the throat or
nasal passage but 10 gets deeper and many remain in lower respiratory tract.
the 100 is readily swallowed.
these particles may not be as dense as sand and thus demonstrate different
aerodynamic behavors due to nonspherical shape. from a risk assessment point
of view this size particle is a problem especially under the circumstances
under discussion.
-----Original Message-----
From: Fritz A. Seiler [mailto:faseiler@NMIA.COM]
Sent: Wednesday, May 05, 2004 3:25 PM
To: radsafe@list.vanderbilt.edu; Bjorn Cedervall
Cc: Joseph L. Alvarez
Subject: RE: Dirty bomb article (Nature)
Hi All,
Here again is a beautiful example of knowing just enough to be
dangerous! In my career as a nuclear physicist I did not come
into real contact with aerosol science until I leaned about it
as an NBC(Nuclear, Biological, and Chemical warfare) officer in
the Swiss Army. Due to its 'National Guard' nature, we had all
kinds of scientists in the NBC defense service. I doubt very
much that the physicists cited in Nature were aware just how
difficult it is to make an inhalable aerosol even in a powerful
chemical explosion. In the Goiana incident we obviously had to
deal with a ready made powder with an unknown spectrum of particle
sizes, and the dirty bomb would produce an equally unkown spectrum.
The two cases can, therefore, not be used to evaluate each other's
consequences. Remember, a particle of about 100 micrometers or more
is a fine grain of sand that has a tendency to fall right past your
face without negotiating the turn needed to enter your mouth or nose.
The best size for inhalation lies at aerodynamic diameters below 10
micrometers or so. In the book Joe Alvarez and I are writing, we
present the reader with a dirty bomb problem that hinges on his
ability to aerosolize a monelclad RaBe source by a shaped explosion.
You can have quite a bit of fun with that! What you need essentially
is the knowledge of an explosive specialist and those do not grow on
trees.
Funny how little expertise you need to scare many people!
Best
Fritz
*****************************************************
Fritz A. Seiler, Ph.D.
Sigma Five Consulting: Private:
P.O. Box 1709 P.O. Box 437
Los Lunas, NM 87031 Tome', NM 87060
Tel.: 505-866-5193 Tel. 505-866-6976
Fax: 505-866-5197 USA
*****************************************************
-----Original Message-----
From: owner-radsafe@list.Vanderbilt.Edu
[mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of Bjorn Cedervall
Sent: Wednesday, May 05, 2004 2:51 PM
To: radsafe@list.Vanderbilt.Edu
Subject: Dirty bomb article (Nature)
http://www.nature.com/nsu/040503/040503-3.html
FYI & best regards,
Bjorn Cedervall bcradsafers@hotmail.com
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