Frequently Asked Questions

Radon is a naturally occurring radioactive gas produced by the decay of uranium found in soil, rock, and water. It is colorless, odorless, and tasteless — completely undetectable without specialized equipment. Radon can seep into homes through cracks in foundations, gaps around pipes, and other openings, where it can accumulate to dangerous levels.

When radon is inhaled, it decays into radioactive particles that can lodge in lung tissue and emit radiation. Over time, this radiation damages DNA and can lead to lung cancer. The EPA estimates radon causes approximately 21,000 lung cancer deaths per year in the United States, making it the second leading cause of lung cancer after cigarette smoking.

The EPA recommends taking action to reduce radon levels if your home tests at 4 pCi/L (picocuries per liter) or higher. They also suggest considering mitigation for levels between 2 and 4 pCi/L, especially if anyone in the household is a smoker. The average indoor radon level in the US is about 1.3 pCi/L; outdoor air is typically around 0.4 pCi/L.

The EPA recommends testing every two years as a general guideline. You should also retest after any significant home renovation (especially to below-grade spaces), after installing or replacing a radon mitigation system, if you make changes to your HVAC system, or when buying or selling a home. If you've never tested, do it now — radon levels can vary significantly between similar homes on the same street.

Professional radon testing should be performed by a certified radon measurement professional. The two nationally recognized certification programs are NRPP (National Radon Proficiency Program, operated by the NRSB) and AARST-NRSD. Both programs require candidates to complete training and pass standardized exams. You can verify a tester's credentials on the certifying organization's website using their certification number.

DIY radon test kits are available at hardware stores and online for $15–$40 plus a lab fee. They are accurate when used correctly and are fine for routine home monitoring. However, for real estate transactions, most buyers, sellers, and lenders require a certified professional using a continuous electronic monitor — DIY kits are not accepted in many real estate contexts. A professional test runs $100–$300.

Professional radon testing typically costs $100–$300 depending on your location, the type of device used, and how quickly results are needed. Short-term tests using charcoal canisters tend to cost less; continuous electronic monitoring (common for real estate) costs more but provides tamper-evident results and faster turnaround. Testing additional areas of the same home may add $50–$100 per area.

Short-term tests run for 2–7 days and provide quick results. They capture a snapshot of radon levels during the test period, which can be influenced by weather, seasons, and home conditions. Long-term tests run for 90 days to a year using alpha track detectors and provide a more accurate picture of year-round average exposure. For initial screening or real estate, short-term tests are typical; for the most accurate assessment, a long-term test or two consecutive short-term tests are recommended.

Radon testing is not federally mandated for real estate transactions, but it is strongly recommended and widely practiced. Many buyers request it as part of their home inspection contingency. Some states have disclosure requirements related to known radon issues. For real estate transactions, the test must typically be performed by a certified professional using a continuous electronic monitor, and results are usually required within 24–48 hours of test completion.

Radon mitigation refers to methods used to reduce indoor radon concentrations. The most common and effective method is sub-slab depressurization (SSD): a pipe is inserted through the concrete floor slab, routed to the exterior above the roofline, and a continuously running fan creates negative pressure under the slab — drawing radon gas out before it enters the living space. A well-installed SSD system can reduce radon levels by 50–99%. Other methods include crawl space encapsulation, block wall suction, and heat recovery ventilators.

Radon mitigation for a typical single-family home costs $800–$2,500. The most common installation — sub-slab depressurization — typically runs $800–$1,500. More complex homes, crawl spaces, or situations requiring multiple suction points may cost more. Always get at least two quotes from certified mitigators. After installation, a post-mitigation retest is essential to confirm the system is working.

Yes — retesting after mitigation is critical and should never be skipped. Wait at least 24 hours after installation, then conduct a short-term radon test. This confirms the system is functioning correctly and that levels have dropped to an acceptable range (below 4 pCi/L, ideally below 2 pCi/L). If levels remain elevated, the system may need adjustment — a stronger fan, additional suction points, or improved sealing. Most certified mitigation contractors will work with you until your post-mitigation test results are satisfactory.