There are cracks in the foundation. Nothing structural. Nothing that's going to threaten the stability of the home, but they're there. Nooks, crannies and holes through which seeps an invisible threat. Colorless, odorless and undetectable by your average human, it is nonetheless the second leading cause of lung cancer in the United States.

Radon is a radioactive gas.  It comes from the natural decay of uranium that is found in nearly all soils.  It typically moves up through the ground to the air above, then into your home through cracks and other openings in the foundation. Your home traps radon inside, where radon levels can build up.  Any home may have radon problems.  This means new and old homes, well-sealed and drafty homes, and homes with or without basements.

Radon from soil is the main cause of elevated radon levels but sometimes radon in homes may enter through well water. And in a small number of cases, home building materials can even give off radon. However, building materials rarely cause radon problems by themselves.

Any home may have radon problems.

Radon gets in through: 1. Cracks in solid floors 2. Construction joints 3. Cracks in walls 4. Gaps in suspended floors 5. Gaps around service pipes 6. Cavities inside walls 7. The water supply

It has been estimated that nearly 1 out of every 15 homes in the U.S. have elevated radon levels.  The Environmental Protection Agency of the US Government has set a threshold of 4 pico curies per liter (pc/L) as the safe level. As humans are exposed to the gas over a period of years, it can have a significant and detrimental effect.

How widespread is the problem? Radon has been found in homes in all 50 states. Certain areas, like the Upstate South Carolina area, are more susceptible than others (http://www.epa.gov/radon/zonemap.html), but no location is immune. Concentrations of radon-causing materials in the soil can be either natural or man-made. Homes built near historic mining operations may be at higher risk. The only way to tell for sure is to have a home tested.

Types of radon testing - Active vs. Passive

Testing for radon comes in two forms: active and passive. Active devises constantly measure the levels of radon in a portion of the home and display those results. Passive devices collect samples over a period of time and then are taken away and analyzed. Either method can help you determine your level of risk.

Professional testing

There are Do-It-Yourself (DIY) radon test kits widely available on the Internet or even at your local home improvement store such as Lowe's or Home Depot.  However, real estate transactions in most states require testing to be performed by a licensed professional.  Engage your HTI home inspector to conduct a radon test properly.

Your home has high concentrations of radon... Now what?

If high concentrations of radon are found in your home, you have several options. Since radon is only a problem when it is concentrated in high volume, improving the ventilation in an area is often sufficient to solve the problem. In other cases, it may be necessary to limit the amount of radon getting into the home by sealing or otherwise obstructing the access points. Once again, a professional should be engaged to ensure that the radon is effectively blocked. Typical radon mitigation systems can cost between $800 and $2500, according to the EPA.  Many reputable HVAC professionals in "high risk" areas are capable of installing radon mitigation systems.

If you're buying or selling a home, radon can be a significant issue. Buyers should be aware of the radon risk in their area and determine whether a radon test is desirable. When in doubt, the EPA always recommends testing. If test results already exist, make sure they are recent or that the home has not been significantly renovated since the test was performed. If in doubt, get a new test done. If you're selling a home, having a recent radon test is a great idea.  By being proactive, you can assure potential buyers that there is no risk and avoid the issue from the start.  Either way, HTI recommends you consult the EPA's Home Buyer's and Seller's Guide to Radon.

So whether you have an old home or a new one, live in an old mining town or in the middle of the Great Plains, radon is a reality. But it is a reality that we can live with. Proper testing and mitigation, can eliminate radon as a health threat. For more information, visit the EPA web site on radon at http://www.epa.gov/radon.