Radon Exposure: Why a 48-Hour Test Might Be Misleading When Buying a Home
Radon Testing When Buying a Home: What You Should Know
When buying a home, you’re advised to check for everything—leaks, cracks, structural concerns—but what about radon? Should you test for radon if you live in North Carolina? The short answer: yes. But with a caveat.
Radon, an odorless and colorless radioactive gas, forms naturally when uranium, thorium, and radium in soil, rock, and water breaks down. It can enter homes through cracks in the foundation, gaps in walls, and other openings. Long-term exposure to elevated radon levels is the second leading cause of lung cancer in the U.S. after smoking, according to the Environmental Protection Agency (EPA) and American Lung Association. So, clearly, radon is worth taking seriously. But there’s a catch: the timing and type of radon testing make all the difference.
The Limitations of Short-Term Radon Testing
Most radon tests conducted during real estate transactions last only 48 hours. While short-term testing is convenient, it comes with limitations. Radon levels fluctuate dramatically due to various factors:
Weather: Rain, snow, and high winds can affect how radon enters a home.
HVAC Usage: Heating and cooling systems can influence air pressure and radon levels.
Seasonal Variations: Winter typically sees higher radon levels due to closed windows and reduced ventilation.
These fluctuations mean a 48-hour test may not represent the home’s long-term radon levels. According to the EPA, long-term exposure—measured as the annual average—is what determines health risks. A short-term test could capture a transient peak or valley, giving an incomplete picture of the home’s radon levels.
What to Do Instead
If you’re buying a home, consider the following:
1. Shift Your Perspective
Treat radon testing as part of the bigger picture, not the sole deciding factor for purchasing a home. A "normal" short-term radon test result doesn’t guarantee consistently low radon levels year-round. Similarly, a high result doesn’t mean the home is unlivable.
Instead of walking away from a potential dream home due to radon concerns, plan for the possibility of future mitigation. Radon mitigation systems are effective and relatively affordable, typically costing between $800 and $2,500, according to the National Radon Program Services. This cost can often be negotiated during the homebuying process. Curious about radon levels here in Wake County and other areas of North Carolina? Check out the EPA’s Map of Radon Zones - North Carolina.
2. Invest in a Continuous Radon Monitor (CRM)
After purchasing your home, a continuous radon monitor (CRM) provides ongoing data about radon levels. CRMs are small devices that track radon fluctuations over time, giving you a comprehensive picture of exposure.
When choosing a CRM, know that there are plenty of monitors on the market that aren’t very accurate. It’s best to consult the National Radon Protection Program’s List of Approved Devices prior to making any purchases.
Proper Placement and Use of CRMs
To get reliable radon readings, placement of your CRM is critical. Here are best practices:
Choose the Right Location: Place the CRM in the lowest livable area of the home where people spend at least four hours per day. Avoid basements used only for storage.
Avoid Interference: Keep the monitor away from exterior walls, vents, windows, or HVAC systems, which could skew readings.
Height Matters: Place the device at least 20 inches above the floor—radon is heavier than air and concentrates at lower levels.
Rotate the Monitor: Consider moving the monitor every six months to check for spatial variability in radon levels.
Why Continuous Monitoring Matters
Radon levels can change over time due to shifting soil, home renovations, or HVAC changes. A CRM ensures you stay informed about these fluctuations and can act quickly if levels rise above the EPA’s action level of 4.0 pCi/L (picocuries per liter).
Final Thoughts
Radon testing is a crucial step when buying a home, but it’s not a perfect science. A short-term test offers a snapshot, but the long-term picture matters more. By approaching radon testing with the right mindset and investing in a quality continuous radon monitor, you can ensure your home remains a safe and healthy place to live.
If radon levels ever rise, mitigation is a manageable, cost-effective solution. And remember, knowledge is power—understanding radon’s risks and behaviors helps you take control of your home’s air quality and your family’s health.
