[ RadSafe ] Questions about radon Deacy product concntration depends on ventilation rate, presence of synthetic decorative plastic surfaces etc

[parthasarathy k s]

Mike Brennan,

An important factor which decides the concentration of radon decay products in air is the ventilation rate. In tropical climates we have seen that air in a room changes every hour or so under "normal" ventilation.

I have made measurements of  the three main decay products of radon, Po-214, Bi 214 and Pb-214  in a basement laboratory over time using a method developed by Raabe And Wrenn a few years ago. Wide variations were seen. Among the many factors that affect the concentrations of the decay products in air is their removal by surfaces of synthetic materials used as decorative plastics. I have demonstrated the deposition of activity by using the surface with and without a conducting aluminium foil covering it. Aluminium foil covered plastic collected less activity. This is due to the electrostatic attraction by the uncovered foil. Some of the decay products are known to carry charge. 

Regards
K.S.Parthasarathy




________________________________
From: "Brennan, Mike (DOH)" <Mike.Brennan at DOH.WA.GOV>
To: radsafe at radlab.nl
Sent: Thursday, 23 April, 2009 22:23:42
Subject: RE: [ RadSafe ] Questions about radon

Hi, Steven.  

I would agree that the conversion from pCi/l to rem is one that has a
lot of "slop" in it, and that there really isn't any way to make it more
precise.  Even if you know the radon concentration exactly (which is far
from a given, as radon levels fluctuate based on a number of factors),
you have to make an assumption about the availability of radon decay
products to be inhaled, which is dependant on things such as dustiness,
floor and wall coverings, etc.  Then you have to make assumptions about
how much radon et al. is inhaled, which is a function of occupation
time, respiration rate, and lung capacity.  The long and short of it is
that it is pretty hard to attach a single number for dose when all that
is known is radon concentration (and that is not well known).  

I have no problem with the statement "That makes it greater that all the
other routine environmental exposures combined."  This is even more true
that it is the largest avoidable environmental exposure (significantly
decreasing exposure from K40, for example, is an exercise in reducing
long-term risk of cancer for short-term risk of death).  

I am not particularly comfortable with the giving a particular number of
lung cancers per year that radon causes or contributes to.  I am
reasonably comfortable with the statement that radon is the number two
cause of lung cancer, and the leading cause among nonsmokers.  There are
a couple of case I am aware of where, even though it can't be proven
that radon caused the cancer in question, I believe it was the likely
cause.  One is a 39 year old woman, never-smoker, who spent an hour per
day running on a tread mill in a basement room that tested at 30 pCi/l.
She died of lung cancer.  Another is a woman, a never-smoker who spent
much of her time, including sleeping, on a floor of her home with radon
levels between 250 and 400 pCi/l.  Lung cancer was discovered on a chest
x-ray taken for an unrelated reason.  I suspect even Dr. Long would
agree that situations like these are not good.  

I have no love for LNT.  I have no emotional attachment to 4pCi/l as an
"Action Level", and if scientifically sound studies said it should be
higher or lower; fine.  I do believe that the higher the radon level,
above some concentration that may be different for different
individuals, and possibly different for the same individual at different
times in their lives, and I have no problem advising people on how to
lower their exposure.  Particularly when they are being exposed to quite
high levels.  

As far as the rest of the site, I've just glanced at a few other parts,
but it doesn't look bad.  If the general public understood things at
this level, the world would be a better place.  There might well be
argument about things like nuclear energy, but they wouldn't be as
stupid.  

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Steven Dapra
Sent: Wednesday, April 22, 2009 5:34 PM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Questions about radon

April 22

         Is anything true in this quote?

         "The "action level" recommended by the Environmental Protection
Agency for radon in the air is 4 picocuries/liter of air. It is
difficult to convert air concentrations to actual exposures in rems or
sieverts, but estimates are in the range of 4 to 14 rem per year at that
concentration. 
That makes it greater that all the other routine environmental exposures
combined."

         Okay, I know the first sentence is true.  Is it difficult to
convert air concentrations to exposure in rems?  Does 4 pC/l equal 4 to
14 rem per year?

         I got the quote from this website
<http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radon.html>.  Scroll
down to the "Radon compared to other radiation sources" sub-heading.
Any comments on the rest of the site?

Steven Dapra



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