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RE: Radon and Respiratory protection
High efficiency filters stop aerosols that carry radon progeny. They do not
stop radon gas.
For a good start on attachment of Rn decay products on aerosol particles,
see
O. Raabe, Concerning the Interactions That Occur Between Radon Decay
Products and Aerosols, Health Physics, Volume 17, Issue 2, pp. 177-185
(1969).
W. Jacobi, Activity & potential alpha energy of 222-Rn & 220-Rn daughters
in different air atmosphere. Health Physics Vol 22, pp. 441-450 (1972).
A look at the book by N.A. Fuchs - The Mechanics of Aerosols (Pergamon
Press, 1964) will bring useful info on filtration and impaction. These
references are fairly old, but aerosol physics was already well developed in
the early 20th century!
A visit to the journal "aerosol physics" would bring recent info, but
nothing that will contradict the above references.
About filtration: HEPA filters will stop about 99.9% of all particles, with
a maximum efficiency at very small and large particle size - The efficiency
is higher for very small particles (less than 0.01 micrometer) because of
their high diffusivity, and for larger particles because of impaction.
Efficiency is minimal at about 0.1 micrometer aerodynamic diameter.
Philippe Duport
International Centre for Low-Dose Radiation Research
Institute of the Environment
University of Ottawa
555 King Edward Avenue
P.O. Box 450, Stn A
Ottawa, ON, Canada, K1N 6N5
Tel: (613) 562 5800, ext. 1270
-----Original Message-----
From: owner-radsafe@list.vanderbilt.edu
[mailto:owner-radsafe@list.vanderbilt.edu] On Behalf Of Jay Beckel
Sent: Wednesday, September 03, 2003 10:12 AM
To: radsafe@list.vanderbilt.edu
Subject: Radon and Respiratory protection
Do HEPA cartridges provide ANY protection at all in a radon atmosphere? Are
there any studies out there that would back up any theories of radon
attachment to particles and therefore being caught up in the HEPA?
Thanks,
J
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