Re: Radon and rain

["Alan R. Marchand" <radarm@accessnv.com>]

Air pressure effects this problem. Track the air pressure to your readings.


this is just my opinion.

Alan Marchand
radarm@accessnv.com

At 11:14 AM 7/27/97 -0500, you wrote:
>My home in New Jersey is on a hill and at one time contained radon levels of
>15 pCi/L in the basement, which required remediation through ventilation of
>a pre-existing French drain system. A stream runs by the side of the house,
>built in 1929. 
>
>After 6 inches of rain fell in 24 hours on July 24, during which time all
>windows in the house were closed, I recorded about 250 cpm throughout the
>basement with a 2 inch GM thin-window pancake, and about half that on the
>upper floors (normal background 40 cpm). This was little plating out of
>radon daughters on the detector window, because when I went outside the
>count rate fell to near normal. The ventilation pump was working. The effect
>was transient: the count rate in the basement was at the background level 24
>hours later.
>
>In winter when the humidity is low I have observed accumulation of radon
>daughters on fabrics and other static-prone surfaces up to 250 cpm, but I
>have never found GM-detectable radon daughters in air before. I assume the
>massive rainfall produced a sudden increase in the groundwater level that
>somehow forced large amounts of radon into the house. Is this a well-known
>phenomenon? Is it possible to estimate the radon concentration from the GM
>count rate?
>
>Jonathan Robert
>jtjat@pipeline.com
>
>
>