Your radon test came back at or above 4.0 pCi/L. Now what? A high radon result is not a reason to panic, but it is a reason to act. Radon exposure accumulates over time, and a confirmed elevated level means the timeline for addressing it should be measured in weeks, not years.
Here is a clear, step-by-step breakdown of what to do after getting a high radon test result.
What a High Radon Level Actually Means
The Environmental Protection Agency sets 4.0 pCi/L (picocuries per liter) as the action level for indoor radon. At or above this concentration, the EPA recommends installing a radon mitigation system to reduce indoor levels. This threshold is based on the point where risk is significant enough and the cost of mitigation is low enough to make action clearly warranted.
Here is a basic reference for understanding radon levels:
| Radon Level | What It Means |
|---|---|
| 0.0 to 1.9 pCi/L | Low risk. No action required. |
| 2.0 to 3.9 pCi/L | Moderate. EPA recommends a follow-up long-term test to confirm annual average. |
| 4.0 pCi/L and above | At or above the EPA action level. Mitigation is recommended. |
| Above 8.0 pCi/L | Significantly elevated. Mitigation should be prioritized. |
The Centers for Disease Control and Prevention identifies radon as the second leading cause of lung cancer in the United States, responsible for approximately 21,000 deaths annually. Exposure does not cause immediate symptoms — the health effects develop over years and decades of cumulative inhalation. A confirmed elevated result is the point where that accumulation stops being theoretical and becomes something to address.
Step 1: Confirm the Result
Before scheduling mitigation work, confirm your result. Short-term radon tests conducted under proper closed-building conditions are reliable, but a single reading can reflect unusual conditions during the test window. If your initial test was a DIY charcoal canister kit, consider confirming with a professional test before investing in mitigation. If your result was produced by a professional continuous radon monitor under documented closed-building conditions, that result is already reliable and you can proceed to the next step.
The EPA recommends confirming with a second short-term test rather than waiting 90 days for a long-term result if the first test was at or above 4.0 pCi/L. Two consistent short-term results are enough basis for a mitigation decision.
Step 2: Do Not Attempt DIY Mitigation
Radon mitigation is not a DIY task. Sealing visible cracks in a foundation slab without a suction system underneath can temporarily reduce radon entry at specific points but does not reduce the negative pressure differential that draws radon into the home. Opening windows increases ventilation and lowers radon levels while the windows are open, but radon returns to prior levels when they are closed. Neither approach constitutes a solution.
Effective radon mitigation requires designing and installing a system that addresses the pressure dynamics beneath the foundation. That requires site assessment, appropriate pipe routing, and fan sizing — the work of a certified radon mitigation contractor.
Step 3: Hire a Certified Radon Mitigation Contractor
Look for a contractor certified through NRPP (National Radon Proficiency Program) or NRSB (National Radon Safety Board). A certified contractor will assess your home’s foundation type and construction, design a system appropriate for your specific situation, and install it correctly.
The standard approach for most homes is sub-slab depressurization (SSD): a pipe is inserted through the foundation slab, a continuously operating fan is attached, and radon-bearing air from beneath the slab is vented above the roofline before it can enter the home. SSD systems typically reduce indoor radon levels by 80% to 99%. Installation usually takes less than a day.
Crawl space homes use variations of this approach, including crawl space depressurization combined with vapor barrier installation. The right system depends on your foundation type and how radon is entering the structure.
Step 4: Retest After Mitigation
After the mitigation system is installed, a post-mitigation retest is essential. This is not optional verification — it is the only way to confirm the system is performing correctly. A system that was installed correctly in most respects but is not fully addressing all radon entry points can still leave indoor levels elevated. The post-mitigation test catches this before you assume the problem is resolved.
The post-mitigation test should be conducted by an independent testing provider, not the same contractor who installed the system. An independent test provides unbiased documentation that radon levels have actually been reduced to an acceptable range. EnviroPro 360 can handle the post-mitigation retest and provide the documentation you need for your property records.
What If the Result Was Between 2.0 and 4.0 pCi/L?
A result in this range does not trigger the immediate action level, but it is not a clearance either. The EPA recommends a follow-up long-term test (90 days or more) to determine whether the true annual average is above or below 4.0 pCi/L. Because short-term tests reflect a specific window, a result of 3.2 pCi/L in summer might correspond to a winter average well above 4.0 pCi/L. Homeowners planning to remain in the home for many years should not dismiss a borderline result without a long-term confirmation.
Schedule a Confirming Test or Post-Mitigation Retest
EnviroPro 360 provides professional radon testing for homeowners throughout Augusta, Evans, Martinez, Grovetown, North Augusta, Aiken, and the CSRA. Whether you need to confirm an elevated DIY result or conduct an independent post-mitigation retest, EnviroPro 360 provides documented results with plain-language interpretation.
Contact EnviroPro 360 to schedule radon testing in Augusta or anywhere in the CSRA.
