AW: [ RadSafe ] Re: Residential radon risk

[Bernard Cohen]

    The only thing I know from my own research is that any one of 
several simple and cheap dust removal devices reduces radon daughters 
(WL) by a factor of 3 or more. My basis for believing that this benefit 
is largely neutralized by increases in unattached fraction are (1) some 
published studies the references to which I cannot now remember, and (2) 
the fact that this method for overcoming radon problems in homes has not 
been widely recommended or implemented, despite the fact that there were 
early relatively powerful promoters like Dade Moeller. For further info 
on this problem, one might contact Dade. I have never made measurements 
of unattched fractions that I considered to be reliable.

GELSG at aol.com wrote:

> 
>Dr. Cohen:
> 
>As I mentioned before, I have not seen much beyond anecdotal evidence for  
>average unattached fraction values for the average home.  My observations  in my 
>own home, both with and without active electrostatic air cleaning, is that  
>there is always some dust.  An electrostatic precipitator certainly helps  to 
>remove dust, but there are many different ways to "resupply" dust to the home  
>environment, some of which I mentioned previously.
> 
>If it were shown that home electrostatic precipitators did not drastically  
>reduce the average unattached fraction (it might not take that many dust  
>particles per cubic meter to provide sites for attachment), would you then agree  
>that use of such a device in the average home situation might substantially  
>reduce lung doses from radon daughters?
> 
>
       ---I do not know enough to be entitled to an opinion on this. One 
would have to take other evidence into account.

>Gerald Gels
> 
>In a message dated 6/2/2005 11:50:03 P.M. Eastern Standard Time,  
>blc+ at pitt.edu writes:
>
>Dear  Philippe:
>Many thanks for this info. If the variation of unattached  fraction is so 
>large, why do mines depend solely on WL? In any case, the  variation in 
>homes can be very much larger because of systems for dust  removal in 
>common use.
>
>
>
>
>
>
>
>Dr. Cohen:
> 
>I generally agree with your work and conclusions on indoor radon.   However, 
>the statement below troubles me.  In theory, in laboratory  conditions, one 
>can approach a UF of 1.0.  However, (and I have seen very  little data on this 
>point) I have never heard of real world UFs of more than  0.1, much less 1.0.  
>If you do have such data, I would like to see  it.  In my house, we always 
>seem to have plenty of dust, even with the  electrostatic precipitator running.  
>I have always believed that, in the  real world of opening doors and leaking 
>windows and cooking and playing  children, there will always be plenty of 
>"replacement dust" particles.  In  that case, I would take exception with your 
>conclusion about electrostatic  precipitators, and state that they would be a very 
>good means of reducing lung  exposure to radon daughters in homes that are 
>not laboratory glove boxes.   As such, we should be actively encouraging, not 
>discouraging, their use.
> 
>Gerald Gels
> 
>_blc+ at pitt.edu_ (mailto:blc+ at pitt.edu)   wrote:
>"As an example, one 
>can drastically reduce the WL by removing the dust (for example, with an  
>electrostatic precipitator), but the newly formed radon daughters have  
>no dust to attach to, so UF = 1.0, and the danger is not  reduced."
>
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