Sump pumps and radon
In recent years, Public Health workers in Iowa have become increasingly concerned about the function of sump pump pits in contributing to high radon levels. Radon is a gas that enters your building from the soil beneath and around your house. These gases can enter your home through the footing drain tile that is connected to the sump pump in your basement. (If you don't have a basement sump pit, this doesn't effect you directly.)
A 2010 study by Linn County Public Health shows graphically the effect of sealed and unsealed sump pumps in contributing to elevated radon levels.
The graphic shows the strong effect of sealed sump pits on radon levels in new homes. For homes with active radon remediation systems, a sealed sump lid reduced radon levels from 2.8 pCi/L to 0.4 pCi/L (reduction below 0.4 pCi/L cannot be achieved reliably, since radon is at or above that level in outdoor air.) For homes with passive radon systems, a sealed sump lid reduced radon levels almost 50 percent, from well over the EPA Action Level to below it. Even for systems without radon remediation systems, a sealed sump lid had a noticeable affect. (Note that homes for the study were targeted in areas where the underlying geology was expected to contribute to high radon levels)
Below is a picture of a sealed sump lid. There are several different kinds; they are readily available from building supply companies and are not expensive. We think it's a good idea, in new construction or existing, to use a sealed sump lid, whether your radon is high, low, or marginal.