I've been trouble-shooting for 3 years my radon problem...but just recently believe
the problem is outdoors and not indoors.

I have an electronic radon monitor that updates reading like every 30 minutes...i've
had it as well for about 3 years.

Basically I've sealed everything a 100% indoors for the most part... the foundation
was completely sealed of cracks... thick radon plastic on top...and vinyl flooring on
top of that..

I realized when I had the windows closed for an extended period of time, the radon
levels would eventually fall.. (especially during the winter when the ground is
frozen and there is snow everywhere...like it is right now)

During the Spring, Summer, and Autumn...if I opened the windows...the radon levels
would slowly increase in the house instead of decrease.... I was pretty baffled by
this, so I put the entire electronic monitor outdoors instead of indoors...and the
levels remained the same or even rose a bit.

This convinced me that the problem is outdoors and not indoors... I live in the
Mountains (Pennsylvania)

And over the 3 year period the numbers generally averaged from 4.0 to
8.0...indoors... but never really got above 9.0 . (currently , since the ground is
frozen...the indoor level is 1.9)

So my next question is...what to do now ? I even put the electronic radon monitor
outdoors on the 2nd deck (elevated)..and the number were about the same there as
well.

So in general, my outdoor radon levels average around 4.0 to 6.0 for the most part...
(the 8.0 I mentioned above was an indoor reading dooring the summer)

The house was built in 1992... I bought it in 2005.

any advice is appreciated

john