I'm a bit doubtful the fan causing so much suction inside the house, that it pulls up radon..
But, I can see where some leaks/ventilation configurations might cause negative pressure, all the way down to the basement.

Currently, my Radon alarm meters are displaying 2.6 ppm, a couple of months back, the readings were 2.5 or less..

I'm going up and unplug my little attic fan, and keep an eye on those radon alarms.

XRinger,

I can assure you that it will. That is how I first got interested in this subject. We had a client in Bowling Green, Kentucky where they started smelling gasoline vapors in the basement. The ultimate source was a leaking underground storage tank. The proximate cause was two powered attic fans that were litterally pullling huge volumes of soil gas into the building. Subsequent air sampling showed high radon levels as well as gasoline constituents.

Of course, if the ceiling/attic interface is air tight, this could not happen. However, it still doesnt justify the expense of a powered attic fan.

Barry Westbrook
℅ DocAir
4014 Flagstone Ct
Franklin, Tn 37069
615-373-2498

I'm not sure what the level of vacuum would be in the basement.
It likely kicks up pretty high when the oil burner fires up, or if the dryer is running!

We have an attic pull-down stairs in the back hall/basement stairway.
It's sealed, but the way it's constructed, doesn't allow for a really good seal.

What also worries me, is the fans in the kitchen & bathroom.
Those pull a suction on the living areas.

One of the projects on my to-do-list is taking care of our radon problem.

Seems like the best way to keep your attic cooler is installing PV.. :D

Absolutely. The top of your attic may be 150 degrees and the bottom 120 degrees, but if your air conditioning ducts are in the 120 degree area, its still heating up the air you just cooled!