Re: LNT models -Constancy of Radon levels over time??

[Tom Mohaupt <tom.mohaupt@wright.edu>]

Stewart raises an interesting point. Radon is not constant. The
concentration has been changing over the years due to buttoning up homes
and filtering air. He suggests these changes could impact Dr. Cohen's
findings. This point can easily applied to residential radon studies done
up to date. It also applies to the Iowa study, which does not correct for
this effect. See "Residential Radon and Lung Cancer Case-Control Study" at
http://www.cheec.uiowa.edu/misc/radon.html. The paper describes the Iowa
radon study methodology for those of you who are interested.
Tom

RadiumProj@cs.com wrote:
> 
>
> This is likely to be a poor assumption over the lifetime of a large fraction
> of today's residents for the following reason. Over the past many decades
> there has been an effort to reduce energy consumption in existing homes by a
> combination of measures [insulation, storm windows, weatherstripping,
> caulking] all of which will reduce air infiltration and increase indoor radon
> levels, on average. Accordingly, the radon levels measured today in the
> "average home" may not reflect the time-averaged radon levels to occupants of
> an older home which might determine a long-term residents' actual
> radon/lung-cancer dose-response relationship. Also many people who grew up in
> older, draftier homes with  likely lower radon levels will have moved into
> homes of newer construction with much higher radon levels due to their being
> built much tighter.
> 
> To the extent that radon levels in the indoor environment are likely to have
> increased with time, both due to the upgrading of older homes and in the fact
> that newer construction is much, much less subject to air infiltration [and
> dilution of indoor radon], resulting in higher radon levels, radon levels
> over time are very unlikely to have been constant with time even thought
> radium levels in local soil are constant.
> 
> If the historical long-term  time-averaged radon levels to residents were
> much  lower to people than assumed based on recent measurements in today's
> homes, this would seem to be a flaw or serious confounding variable not
> addressed to my knowledge, in Dr. Cohen's argument regarding the lack of
> correlation between elevated radon levels and lung cancer rates.
> 
> Stewart Farber, MS Public Health [Air Pollution Control]
> Public Health Sciences
> email: radiumproj@cs.com
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-- 
Thomas Mohaupt, M.S., CHP
University Radiation Safety Officer

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