This section is meant to provide a short overview only. Those wishing to know more should follow the EPA link at the bottom of the page.
What is Radon?
Radon is a colorless, odorless, radioactive gas which is a product of the natural decay of uranium located deep underground.
Lighter than air, it rises through cracks and fissures in the ground and can enter a home through cracks, joints and openings in a concrete slab, or move easily through floor, wall and ceiling framing assemblies. Homes with concrete slab floors, basements and crawlspaces are all vulnerable to radon entry.
Although some radon problems can come from water sources, most are from soil gas.
What Are the Health Risks?
Because it's a radioactive gas, radon will eventually decay. When radon decays it emits tiny radioactive particles. If radon has been inhaled and is inside lungs, these particles can strike lung cells, causing abnormal lung cell replication, otherwise known as cancer.
The U.S. Environmental Protection Agency (EPA) calls radon the second leading cause of lung cancer in the U.S.
No "safe" level of radon exists and the effects may be delayed for years, may affect children more than adults, or may never cause health problems. Generally, exposure to higher levels and longer exposure times increase the odds of developing radon-related health problems.
Where is Radon Found?
Some parts of the U.S. are more likely to have elevated levels of radon than others. The EPA National Radon Map provides great information on U.S. radon levels nationwide.
The only way to determine whether a home has levels which may pose a health risk it to have the home tested.
A number of testing (radon-measuring) devices are available, ranging from simple do-it-yourself charcoal canisters found at most hardware stores to sophisticated monitors with security features which provide immediate results at end of the typical 48-hour test.
Testing for real estate transactions should comply with EPA protocols and be performed by a qualified neutral third party. Qualifications may vary by state.
Testing requires "closed house conditions," and under certain conditions, opening windows in upper levels of the home make actually increase radon levels in the home due to "stack effect," or the rising of heated air.
Stack effect can pull gas out of the soil.
Radon levels are measured and described in picoCuries of radon per liter of air, typically shown as "pCi/L". The EPA action limit is the limit at which the EPA recommends that mitigation take place. At this time (2007) this limit is 4 pCi/L.
What is Mitigation?
The process of lowering radon levels is called "mitigation." Mitigation may involve different approaches or combinations of approaches, depending on the situation and severity of the problem. Mitigation is often very successful.
For more information, read "A Home Buyer's and Seller's Guide to Radon," an excellent guide by the EPA.