Radon is a dangerous, colorless and odorless gas that results from the natural breakdown of uranium in soil, rock and water. Radon can leak into homes through cracks in foundation walls and enter drinking water from private wells. While brief exposure to radon in outdoor air is relatively harmless, long-term, heavy exposure can lead to lung cancer, and can cause other health problems. It is estimated that radon causes 21,000 lung cancer deaths in the United States each year, second only to cigarette smoking. The risk to smokers is much higher than for non-smokers.
Unlike other radioactive gases that can be found in the environment, radon is not a chemical compound. In its gaseous form, radon dissipates quickly into the atmosphere, but if it seeps into buildings and concentrates in small spaces, such as your home, it can become dangerous. Radon in your house can be caused by a number of factors, such as the type of soil and rocks, construction materials and the way that your home is built, but it can also result from a combination of factors.
The most common route for radon to enter the home is from groundwater radonmåling that has accumulated in the soil and moves up through cracks in the foundation, or in a basement with sump pump systems. Homes that are surrounded by bedrock or other rock formations are more likely to have radon seep into the house through groundwater, especially if the house has a basement.
In addition, radon can also leak into a home through the bare floor of a crawl space or through construction joints, and may be present in water from private wells. Although this is less common, it is still a possibility for many homeowners with wells.
While there is no specific level of radon in the water that can be considered safe, the EPA recommends action when concentrations reach 4 picocuries (pCi/L) and above. The agency also encourages homeowners to consider reducing concentrations of radon in drinking water in other ways, such as by installing a radon mitigation system or by using another source of water, such as municipally supplied water or rainwater gathered from rooftops.
There is no requirement that private well owners test their drinking water, although local Boards of Health and mortgage lenders often require a sample to be tested. MassDEP strongly recommends that all owners of private wells get their well water tested for radon, especially if they have a basement, and that they use a state certified testing laboratory. This is because the water in a private well is not subject to EPA standards, and therefore a well owner has no way of knowing whether or not their water contains toxic levels of radon.