Radon is a naturally occurring radioactive gas without color, odor or taste. Radon gas is one part of a natural radioactive process, known as "decay", where larger, more complex natural elements such as uranium and radium break down into small energy particles. When this gas decays, products known as "daughters" are created. Radon gas itself is relatively harmless until it decays into these daughters, which in turn release damaging energy particles.

Radon daughters attach themselves to dust particles floating in the air. When inhaled they can become lodged in the lungs. As these radon daughters decay, they release energy bursts which can damage lung cell tissue. Prolonged exposure to radon can cause lung cancer. Scientific research indicates that at least a 10 to 20 year incubation period is required before a lung cancer develops.

Scientists estimate that indoor radon is the number one cause of lung cancer in non-smokers and the number two cause of lung cancer (after smoking) in the United States. Up to 20,000 Americans may die each year as a result of radon exposure. The Environmental Protection Agency (EPA) considers radon to be the most significant environmental health risk we face today.

Radon comes primarily from the soil under a building. Radon can be found almost anywhere because radium, the "parent" of radon, is present in most soils. Average concentrations of radium are usually low, and radon gas will usually migrate harmlessly into the atmosphere through the soil. However, if a building is erected over a source of radon, the gas can become trapped inside and build to hazardous levels. The highest concentrations of radon are typically found in basements, however heating and air conditioning systems can quickly spread radon to other parts of a building.

Radon usually enters buildings mixed in with gasses from the soil. However well water can also be a source. Common entry points include: cracks in basement floors, slab joints, floor drains, sump pits and porous cinder block walls. Radon is drawn through these openings as a result of the "stack effect" which is caused by the difference in air temperatures indoors and outdoors. As heated air rises and leaves the building, (much like a hot air balloon) radon is drawn in at the lower points of the foundation. The operation of fireplaces, heating and cooling systems, clothes dryers and exhaust fans can increase the rate of radon entry.

One of the most common radon test types is the activated carbon test. Using this technique, a small canister of activated charcoal is placed in the lowest livable area of a home or commercial building (the basement, if you have one) for several days. After exposure, the canister is sealed and sent to a laboratory for analysis. Charcoal canister tests help you determine the radon concentration present at the time of the test.

Other test devices include electronic continuous radon monitors (CRM's), which can be used to detect and document radon levels on an hourly basis. This type of test is especially valuable when you are involved in purchasing a home and want to prevent tampering with the test device. Certain monitors can also be used to locate primary radon entry points.

The Environmental Protection Agency's website is an excellent source of up to date information.