Radon is a naturally occurring, odorless, colorless, and radioactive gas that originates from the decay of uranium found in soil and rock formations beneath the earth’s surface. This gas can seep into any building through cracks in the foundation, construction joints, or other openings, accumulating to dangerous levels indoors. While the average indoor radon concentration in Texas is generally lower than the national average, the gas is definitively present across the state. Homeowners should understand that the state’s geology creates varying degrees of risk, confirming the need for localized testing.
How Radon Levels Vary Across Texas
The risk of elevated indoor radon levels is not uniform across Texas but is highly dependent on local geology and soil composition. The U.S. Environmental Protection Agency (EPA) uses a system of three zones to classify radon potential, with most of Texas falling into Zone 2 (moderate potential) or Zone 3 (low potential). However, this broad classification can be misleading because radon exposure is extremely localized, and high readings can occur even in Zone 3 areas.
Specific geological features contribute to higher-risk pockets, such as the uranium-bearing granite deposits found in the Central Texas Llano Uplift region. The most significant area of elevated concern is the Panhandle, where a sizable number of homes have reported high radon concentrations. The Panhandle is the only region in Texas to report a significant number of homes with readings exceeding 20 picocuries per liter (pCi/L). Other areas with suspected potential for elevated levels, based on geology and survey results, include the Big Bend area and regions with historical uranium mining activity in South Texas.
Understanding the Health Risks
Radon poses a health risk because, as the gas decays, it produces tiny, solid radioactive particles called decay products. When these particles are inhaled, they become trapped in the lungs, where they continue to emit radiation. This radiation damages the DNA of the cells lining the airways, which can lead to the development of lung cancer over many years of exposure.
Radon exposure is estimated to be the second leading cause of lung cancer in the United States, after cigarette smoking. Scientists estimate that radon is responsible for approximately 21,000 lung cancer deaths annually. This makes the invisible gas the leading cause of lung cancer among people who have never smoked. The risk is significantly compounded for current or former smokers, as the synergistic effect of radon and tobacco smoke dramatically increases the likelihood of developing the disease.
Simple Steps for Home Testing
The only reliable way to determine the radon level inside a home is through testing, which is both simple and inexpensive. Two primary methods are available: short-term tests and long-term tests.
Short-term test kits, often using a charcoal canister, remain in the home for a duration of two to seven days and are commonly used for initial screenings or real estate transactions. These tests provide a quick snapshot of the radon concentration but may miss fluctuations caused by daily or seasonal weather changes.
Long-term tests, which typically use an alpha track detector, are conducted for 90 days or longer and provide a more accurate annual average reading. Because radon levels can fluctuate significantly throughout the year, the long-term test is generally considered the best measure for assessing the true health risk.
Testing must be performed on the lowest occupied level of the home under “closed-house conditions,” meaning windows and exterior doors are kept closed as much as possible during the testing period. Test kits are easily accessible from online retailers, hardware stores, and state or local health departments.
When Mitigation is Necessary
The EPA has established an action level of 4.0 pCi/L, which is the threshold at which homeowners are strongly advised to take steps to reduce the radon concentration. Even if test results are between 2.0 and 4.0 pCi/L, the EPA recommends considering remediation, as there is no known safe level of exposure. The goal of mitigation is to lower the indoor radon level to below the 4.0 pCi/L action level, though lower levels are always more desirable.
The most common and effective method for reducing radon levels is a technique called Sub-Slab Depressurization (SSD). This system involves installing a vent pipe and fan to draw the radon gas from beneath the foundation and safely vent it outside the home. While sealing foundation cracks and other entry points can help, it is rarely sufficient on its own and is typically used in conjunction with an SSD system. Any mitigation system should be installed by a qualified, EPA-certified, or state-licensed professional.