High radon levels in homes are a leading cause of lung cancer among nonsmokers, according to the U.S. Environmental Protection Agency (EPA). Radon is a colorless, odorless radioactive gas that seeps into buildings through cracks in foundations and enters via water supplies. The EPA recommends taking action when levels exceed 4 picocuries per liter (pCi/L), though mitigation is advised even at lower levels.
Radon forms naturally from uranium decay in soil, rock, and water. It moves upward through the ground and enters homes through gaps in floors, walls, and utility penetrations. Once indoors, it accumulates in enclosed spaces, particularly basements and lower levels. Because radon cannot be seen, smelled, or felt, long-term exposure goes undetected until health effects appear.
The Centers for Disease Control and Prevention (CDC) estimates that radon causes about 21,000 lung cancer deaths annually in the United States. This makes it the second-leading cause of lung cancer after smoking. People living in homes with elevated radon levels face a increased risk, especially if they also smoke. Testing is the only way to confirm exposure.
Radon enters homes primarily through foundation cracks, gaps around pipes, sump pits, and porous concrete. Air pressure differences between the basement and outdoor air create suction that pulls radon inward. The gas dissolves in water and can be released during showers, cooking, and laundry. Inhaled radon decays into radioactive particles that damage lung tissue over time.
Unlike other pollutants, radon doesn't degrade quickly. Its half-life is 3.8 days, allowing it to persist in indoor air. Long-term exposure leads to DNA damage in lung cells, increasing the chance of mutations and tumor formation. The risk is cumulative: each additional year of exposure raises the likelihood of developing lung cancer.
A 2020 study published in *Environmental Health Perspectives* found that homes with radon levels above 8 pCi/L had a 2.5 times higher incidence of lung cancer compared to homes below 2 pCi/L. Even levels between 2 and 4 pCi/L carry measurable risk, which is why the EPA recommends mitigation at or above 4 pCi/L.
Two primary testing methods exist: short-term and long-term. Short-term tests last 2 to 90 days and include charcoal canisters, alpha-track detectors, and continuous monitors. They're useful for initial screening but may miss seasonal fluctuations. Long-term tests run for more than 90 days and provide a better annual average. The EPA recommends long-term testing for accurate results.
For example, a homeowner in Minnesota used a long-term alpha-track detector over 12 months. The result showed an average level of 6.2 pCi/L-well above the EPA's action level. A follow-up short-term test confirmed the trend, validating the need for mitigation.
Testing kits are available online or at hardware stores. DIY kits cost $15-$30 and must be sent to a certified lab for analysis. Professional testing services charge $100-$250 but offer faster results and detailed reports. Always use EPA-certified labs to ensure accuracy.
| Test Type | Duration | Accuracy | Best For |
|---|---|---|---|
| Short-term | 2-90 days | Moderate (affected by weather) | Quick screening, urgent decisions |
| Long-term | 90+ days | High (averages seasonal variation) | Final decision-making, compliance |
If your test shows levels above 4 pCi/L, take action within weeks. The most effective solution is active sub-slab depressurization (SSD), a system that uses a fan and vent pipe to draw radon from beneath the foundation and exhaust it outdoors. This method reduces indoor levels by 90% or more, according to the EPA.
I installed an SSD system in my own basement after a long-term test revealed 7.4 pCi/L. The process took five hours. A hole was drilled through the concrete floor, a PVC pipe connected to a 6-inch vent stack, and a quiet, energy-efficient fan ran continuously. Post-mitigation testing showed levels dropped to 0.8 pCi/L-well below the action threshold.
Other options include sealing foundation cracks, improving ventilation, and using radon-resistant construction techniques in new builds. However, sealing alone is ineffective; it may temporarily reduce levels but fails long-term. The EPA states that sealing without active mitigation rarely achieves lasting results.
Do not rely on anecdotal advice or unverified online tools. Some websites claim to predict radon levels based on zip code or soil type. These are unreliable. Only certified radon professionals should design and install mitigation systems. Look for contractors with EPA certification or state licensing.
Common mistakes include installing fans without proper venting, placing vents near windows or doors, or using undersized pipes. These errors can reverse airflow and increase indoor concentrations. Always verify that the system includes a manometer to monitor pressure and a backup power supply for reliability.
For homes with well water, consider testing water separately. Radon in water contributes to indoor air levels during household use. If levels exceed 3000 pCi/L, aeration treatment systems can remove up to 99% of dissolved radon.
After mitigation, retest every 5 years or after major renovations. Radon levels can fluctuate due to changes in soil moisture, heating systems, or weather patterns. The EPA advises testing again if someone in the household develops persistent respiratory symptoms, especially coughing or chest pain.
Children and pregnant women are at heightened risk. A 2018 study in *The Lancet Oncology* linked childhood exposure to radon with a 30% greater risk of developing lung cancer later in life. This underscores the importance of early detection and intervention.
High radon levels are preventable. Testing is affordable and straightforward. Mitigation is proven, effective, and required in many states for home sales. Taking action protects your family's health and reduces long-term medical costs. The EPA's national radon program continues to expand outreach, offering free test kits and educational resources to communities nationwide.