Radon is a colorless, odorless, and tasteless naturally occurring radioactive gas. It forms from the breakdown of uranium, which is present in nearly all soil and rock. This gas moves up through the ground and can enter a building through cracks and other openings in the foundation. Understanding the potential for exposure is an important step in protecting indoor air quality, especially for Texas residents, where the state’s diverse geology means that radon prevalence is highly localized.
Radon Levels and Geographic Distribution in Texas
While Texas is often viewed as having a relatively low geologic potential for radon compared to other parts of the country, elevated indoor levels have been found in every region. The state’s average indoor radon concentration is approximately 2.1 picocuries per liter (pCi/L), which is higher than the national indoor average of 1.3 pCi/L. The U.S. Environmental Protection Agency (EPA) classifies counties into three zones based on their predicted average indoor radon screening levels.
The majority of Texas counties fall into Zone 2 (moderate potential, 2–4 pCi/L) or Zone 3 (low potential, below 2 pCi/L). However, even in Zone 3 counties, individual homes can register high concentrations due to specific local soil conditions and house construction characteristics. The concentration of uranium in the underlying soil, rock, and water dictates the radon potential, which varies significantly across the state.
For instance, parts of the Panhandle area show moderate to high average radon levels. The Texas Coastal Plain, while generally lower risk, contains localized areas where specific geological formations, such as glauconitic sands and carbonaceous shales, can contribute to higher radon potential. Radon entry is a highly localized phenomenon, meaning two houses built side-by-side can have vastly different indoor levels. Factors such as foundation type, the presence of cracks, and the degree of ventilation all influence how much gas accumulates indoors.
The Health Risks of Radon Exposure
Exposure to elevated indoor radon levels is a recognized health hazard because the gas is radioactive. Once radon is breathed in, it decays into solid, highly radioactive particles called radon progeny. These decay products attach to dust particles in the air, which are then inhaled.
When these particles are inhaled, they can lodge deep within the lungs and emit alpha radiation. This radiation damages the cells lining the lung tissue, which can ultimately lead to the development of lung cancer. Radon exposure is considered the leading cause of lung cancer among non-smokers in the United States.
The health risk associated with radon is cumulative; the longer a person is exposed to high concentrations, the greater the likelihood of cellular damage. The EPA estimates that radon is responsible for thousands of lung cancer deaths annually, making it the second-leading cause of the disease overall, after smoking. The risk is especially pronounced for individuals who smoke, as the combined exposure creates a powerful synergistic effect that significantly increases the risk of lung cancer.
Testing and Mitigation for Texas Homeowners
The only reliable way for a homeowner to know the radon level inside their house is through testing. Testing is a simple process using either short-term or long-term kits, which are available to consumers. Kits should be placed in the lowest lived-in level of the home. Short-term tests measure concentration over two to ninety days, while long-term tests are conducted for more than ninety days, providing a more accurate representation of the annual average exposure.
Test results are measured in pCi/L. The EPA recommends that a homeowner take action to reduce the concentration if the level is 4 pCi/L or higher. Because there is no known safe level of radon exposure, the agency also suggests considering mitigation for levels between 2 pCi/L and 4 pCi/L. Professional testing is routinely recommended during real estate transactions to ensure accurate measurements.
Mitigation Techniques
If testing reveals an elevated radon level, the most effective method for reduction is Sub-Slab Depressurization (SSD). The SSD system works by installing a vent pipe and a specialized fan that draws air from beneath the home’s concrete slab or foundation. This active suction creates a negative pressure field under the house, preventing the radon gas from entering the structure.
The fan safely exhausts the collected radon gas through the vent pipe, typically above the roofline, where it quickly dissipates into the outdoor air. This method is highly efficient and can consistently reduce indoor radon levels to below the 4 pCi/L action level. Secondary mitigation efforts include sealing visible cracks and openings in the foundation to limit entry points for the gas. Improving home ventilation can also help to dilute the concentration of radon that has already entered the indoor air.