What is radon? Radon is a radioactive gas that has no smell, taste, or color. It comes from the natural decay of uranium that is found in nearly all rock and soil. When geologic conditions are favorable, the potential increases for high indoor levels of radon.

If radon is natural, why is it a hazard? Outdoor radon levels never reach dangerous concentrations because air movement scatters radon into the atmosphere. Radon is a hazard in buildings because the gas collects in enclosed spaces.

What conditions must be present for high indoor-radon levels? Four conditions must be present. The building must:

1. be built on ground that contains sufficient uranium.
2. have underlying soil that allows easy movement of radon.
3. have porous building materials, cracks, or other openings below the ground surface that allow radon from soil to enter the building.
4. have a lower air pressure inside than in the soil around the foundation.

Can radon enter buildings in water? Radon is easily dissolved in water and is released into the air during water use. However, water rarely contributes significantly to high indoor-radon levels. High levels of radon have never been found in Utah's public-water supplies, but may be present in well water. If indoor-radon levels are not high, don't be concerned with radon in water.

What are the health risks of radon? Radon decays into radioactive particles that can be trapped in the lungs when inhaled. These particles release small bursts of energy that damage lung tissue and may lead to lung cancer. Radon is the second leading cause of lung cancer in the United States. Only smoking causes more lung-cancer deaths, and smoking combined with radon is a particularly serious health risk. Chances of getting lung cancer are higher from the combination of smoking and radon than from either source alone. Not everyone who is exposed to radon develops the disease, but the chances increase with increasing levels of radon and length of exposure. The amount of time between exposure and onset of the disease is usually many years.

How do I test for radon? There are two general ways to test for radon: (1) short-term testing takes from two to 90 days, depending on the device; (2) long-term testing takes more than 90 days. The U.S. Environmental Protection Agency (EPA) recommends a short-term test first and, if high levels of radon are found, follow up with either a long-term test or a second short-term test. Low-cost, "do-it-yourself" radon test kits are available both through the mail and in retail outlets, or you can hire a trained contractor. Make sure the test kit has passed EPA's testing program or the contractor is EPA qualified.

What can I do if my home has high levels of radon? Levels of radon gas are measured in picocuries per liter of air (pCi/L). The EPA suggests that occupants of homes with radon levels above 4 pCi/L take action to reduce indoor-radon concentrations. There are several hazard-reduction techniques that cost about the same as other common home repairs.

By Barry J. Solomon, Utah Geological Survey

For testing procedures in Utah contact:
Division of Radiation Control, P.O. Box 144850, Salt Lake City, UT 84114-4850, (801) 536-4250

Radon Maps

Radon-hazard potential in the Sandy-Draper Area, Salt Lake City, Utah; UGS Public Information Series #18, September, 1993 pdf
In the Sandy-Draper area, soil with the greatest potential for high indoor-radon levels is common on the east bench at the mouth of Little Cottonwood Canyon. This soil is derived from granitic rock in the canyon in the Wasatch Range.

Radon-hazard potential in the Provo-Orem Area, Utah County, Utah; UGS Public Information Series #21, November, 1993 pdf
In the Provo-Orem area, soil with potential for higher indoor-radon levels is common on the east bench and on alluvial fans along the Wasatch Range front. This soil is derived from black shale and metamorphic rock in the mountains.

Radon-hazard potential in the St. George area, Washington County, Utah, B.J. Solomon, fold-out, 1996, Public Information Series #35 Free pdf

Radon-hazard potential in Ogden Valley, Weber County, Utah, by B.J. Solomon, 2 p. 1996, PI-36 Free pdf

Radon-hazard potential in western Salt Lake Valley, Salt Lake County, Utah, by B.D. Black, 2 p. PI-43 Free pdf

Radon-hazard potential in Tooele Valley, Tooele County, Utah, by B.D. Black, 2 p. PI-44 Free pdf

Radon-hazard potential in the lower Weber River area, Weber and Davis Counties, Utah, by B.D. Black, 2 p. PI-45 Free pdf

Radon-hazard potential in southeastern Cache Valley, Cache County, Utah, by B.J. Solomon and B.D. Black, 2 p. PI-46 Free pdf

Radon-hazard potential in the central Sevier Valley, Sevier County, Utah, by B.J. Solomon, 2 p. PI-47 Free pdf

Related Publications and Maps

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Related Websites

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