Radon is a colorless, odorless, and tasteless radioactive gas that poses a significant environmental health concern in Utah. This naturally occurring substance is a byproduct of the decay chain of uranium, which is present in nearly all soil and rock. As a noble gas, radon moves easily through the ground and can enter buildings through foundation cracks and other openings. Once trapped inside a home, it accumulates to concentrations that increase the risk of lung cancer over time.
Prevalence and Risk Zones Across Utah
Radon is common across Utah, with the statewide average indoor level (4.5 pCi/L) being more than three times the national average (1.3 pCi/L). This elevated concentration means nearly one in three Utah homes tested have radon levels at or above the Environmental Protection Agency (EPA) action level of 4.0 pCi/L.
The highest potential for elevated indoor radon levels is found in the northern and eastern parts of the state, particularly along the Wasatch Front and in the mountainous regions. Counties like Wasatch, Cache, and Summit have some of the highest mean radon levels, with Wasatch County showing an estimated mean as high as 9.6 pCi/L. Many cities along the Wasatch Front corridor, including Brigham City, Heber City, and parts of Salt Lake County, also report a high percentage of homes with dangerous levels.
Exposure to elevated radon levels is the second leading cause of lung cancer after smoking. While the EPA recommends action at 4.0 pCi/L, the World Health Organization (WHO) suggests reducing levels if they are at or above 2.7 pCi/L. This indicates that even concentrations below the EPA’s threshold still pose a risk. Given the state’s high prevalence, testing a home is universally recommended regardless of its specific location.
Geological Factors Contributing to High Radon
The primary factor driving Utah’s high radon levels is the state’s underlying geology, which is rich in the source material for the gas. Uranium, which decays into radium and then into radon, is found in the state’s soil and rock formations. This includes uranium-enriched rocks such as granite, metamorphic rock, and certain black shales, which are prevalent throughout the state. Utah is historically the third-largest uranium-producing state, confirming the abundance of this source material.
Once radon is generated in the ground, its movement is facilitated by the permeability and porosity of the soil and rock. Many areas of Utah have well-drained, porous soils that allow the gas to migrate easily upwards toward the surface and into buildings. The presence of geologic fault lines and fractured bedrock can also create preferential pathways for radon to travel quickly from deep underground to the surface.
The way homes are constructed also influences how much gas accumulates indoors. Radon typically enters a home through openings in the foundation, such as cracks in the slab, construction joints, or gaps around utility pipes. Because many homes in Utah, especially those in colder climates, are tightly constructed and have basements, this combination of easy entry and limited ventilation allows the gas to become trapped and build up to high concentrations. The slight difference in air pressure between the inside of a warm home and the colder soil outside can even draw the gas indoors through a process known as the stack effect.
Essential Steps for Home Testing and Mitigation
Testing is the only method to accurately determine the radon level inside a home, as the gas is undetectable by human senses. Homeowners can obtain a do-it-yourself radon test kit from state programs, home improvement stores, or certified testing professionals. The EPA recommends starting with a short-term test, which typically takes between two and seven days to complete, to get a quick initial measurement.
If the short-term test result is 4.0 pCi/L or higher, a follow-up test is necessary to confirm the reading. This secondary test should be either a second short-term test or a long-term test conducted for more than 90 days. The long-term test provides a more accurate representation of the home’s year-round average. If the average of the two short-term tests or the result of the long-term test is 4.0 pCi/L or above, mitigation is recommended.
Mitigation involves installing a system to reduce the indoor radon concentration. The most common and effective technique is Active Soil Depressurization (ASD). This system uses a vent pipe and a continuously operating fan to draw radon from beneath the foundation and safely vent it above the roofline. Sealing obvious cracks and openings in the foundation is a secondary measure to limit entry points.
Mitigation systems are best installed by certified professionals who can tailor the design to the home’s specific foundation and geological conditions. Certified mitigators can generally reduce radon levels significantly, often to 2.0 pCi/L or below. After the system is installed, a post-mitigation test is required to confirm that the radon levels have been successfully lowered.