As of August 2005, 6,668 homes have reported results to the project with 37% of the homes testing high for radon. It is difficult to predict which homes may have high radon levels. Homes built side by side, on the same soil or rock, or with similar designs, can have very different radon levels. Therefore, it is recommended that all homes be tested. No level of radon is considered absolutely safe, radon levels in a home should be reduced as much as possible. The amount of radon in the air is measured in picoCuries per Liter of air, or pCi/L. The EPA recommends fixing your home if the results of one long-term test or the average of two short-term tests taken in the lowest lived-in area of the home show radon levels of 4 pCi/L or higher. The higher the radon level, the more quickly you should have your home fixed. If a test indicates an elevated level of radon, reducing the level is usually easy and inexpensive. Sometimes homeowners can do the work themselves, although it is recommended that they seek professional guidance or have the work done by a professional, EPA-certified radon mitigator. However, if you want to do the work yourself, please call the Radon Hotline number to obtain a technical assistance document. There are several methods a contractor can use to lower radon levels in your home. Some techniques prevent radon from entering your home, while others reduce radon levels after it has entered the home. EPA generally recommends methods that prevent radon entry. These systems use a pipe to remove radon gas from below the concrete floor and the foundation before it can enter the home. If you live in an area with high radon levels and are building a new home, you should consider installing radon-resistant construction features. It is more cost-effective to include these features while building a home, rather than fixing an existing home.