Frequently Asked Questions

The following information has been provided by the United States Environmental Protection Agency.

For more information, please visit www.EPA.gov/Radon.

1. What is radon?

Radon is a naturally occurring, colorless, odorless, tasteless gas. It is formed from the radioactive decay of uranium in the ground. Because uranium is essentially ubiquitous (being or seeming to be everywhere at the same time) in the earth's crust, radium-226 and radon-222 are present in almost all rock and all soil and water.

The amount of radon in the soil depends on soil chemistry, which varies from one house to the next. Radon levels in the soil range from a few hundred to several thousands of pCi/L (pico Curries per Liter). The amount of radon that escapes from the soil to enter the house depends on the weather, soil porosity, soil moisture, and the suction within the house.

2. How does radon enter my home?

Radon gas can move through small spaces in the soil and rock on which a house is built. It can seep into a house through dirt floors, cracks in concrete floors and walls, floor drains, sumps, sump pumps, joints, tiny cracks, or pores in hollow-block walls.

In outdoor air, radon is diluted to such low concentrations that it does not present a safety hazard. However, once inside an enclosed space (such as a house), radon can accumulate. Indoor levels depend on a building’s construction and the concentration of radon in the underlying soil.

3. What are the dangers of radon exposure?

There are no immediate symptoms from exposures to radon. The only known health effect associated with exposure to elevated levels of radon is an increased risk of developing lung cancer. Based on an updated Assessment of Risk for Radon in Homes (see www.epa.gov/radon/risk_assessment.html ), radon in indoor air is estimated to cause about 21,000 lung cancer deaths each year in the United States. Smokers are at higher risk of developing radon-induced lung cancer. Not everyone exposed to elevated levels of radon will develop lung cancer, and the time between exposure and the onset of the disease may be many (5-25) years.

See also radon health risks at www.epa.gov/radon/healthrisks.html

Read "A Citizen's Guide to Radon" at www.epa.gov/radon/pubs/citguide.html

4. What can I do to protect myself and my family from radon?

The first step is to test your home for radon and have a remediation system installed if it is at or above EPA's Action Level of 4 picocuries per liter. There is no safe level of radon, so you may want to take action if the levels are in the range of 2-4 picocuries per liter. Generally, levels can be brought below 2 pCi/l fairly simply.

The best method for reducing radon in your home will depend on how radon enters your home and the design of your home. For example, sealing cracks in floors and walls may help to reduce radon. There are also systems that remove radon from the crawl space or from beneath the concrete floor or basement slab that are effective at keeping radon from entering your home. These systems are simple and don't require major changes to your home. Other methods may be necessary.

People who have private wells should test their well water to ensure that radon levels meet EPA's newly proposed standard.

In 1988, EPA and the U.S. Surgeon General issued a Health Advisory recommending that all homes be tested below the third floor for radon. They also recommended fixing homes with radon levels at or above 4 picocuries per liter (pCi/L), EPA's National Voluntary Action Level. EPA and the Surgeon General also recommend that schools nationwide be tested for radon.