Radon Action Level Calculator
Enter your radon test result to see EPA-aligned guidance on what it means and what to do next. Based on the EPA "A Citizen’s Guide to Radon."
This tool is for general guidance based on EPA thresholds and is not a substitute for professional testing or advice.
What Each Radon Level Means
| Result (pCi/L) | Status | EPA-aligned guidance |
|---|---|---|
| Less than 2.0 pCi/L | Low | Below the level where the EPA suggests considering action. Re-test about every two years, since levels can change. |
| 2.0 to 3.9 pCi/L | Consider mitigation | Below the 4.0 action level but elevated. The EPA notes you may wish to consider fixing the home, since there is no risk-free level. |
| 4.0 pCi/L and above | EPA action level | At or above the EPA action level. The EPA recommends fixing the home. Connect with a credentialed specialist for a mitigation quote. |
Source: US EPA, "A Citizen’s Guide to Radon." The action level is 4.0 pCi/L.
What pCi/L Actually Means
Every US radon result comes back in pCi/L, which is short for picocuries per liter of air. A curie is a measure of how fast a radioactive material decays; a picocurie is a trillionth of one; and the "per liter" part makes it a concentration, how much radon is sitting in a given volume of the air in your house. Nothing about the number is visible or smellable, which is why testing is the only way to know it.
A bare number means nothing without something to compare it to. Here is the scale the EPA publishes, with the international unit alongside, because most of the world reports radon in becquerels per cubic meter instead:
| Reference point | pCi/L | Bq/m3 |
|---|---|---|
| Average outdoor level | 0.4 | 15 |
| Average indoor level | 1.3 | 50 |
| Level at which the EPA recommends fixing the home | 4 | 150 |
| Iowa state average | About 8.5 | Not published in these units |
Outdoor, indoor and 4 pCi/L rows with their Bq/m3 equivalents: US EPA, Health Risk of Radon, read 2026-08-13. Iowa average: Iowa HHS.
Read the Iowa row against the one above it. The state average is roughly six times the national indoor average and about twice the level at which the EPA recommends fixing a house. A number that would be a bad result almost anywhere else is an ordinary Tuesday in Iowa, and a result close to the national average is a genuinely good one here.
Remember that all 99 Iowa counties are EPA Radon Zone 1, and the Iowa state average is around 8.5 pCi/L per Iowa HHS, so elevated results are common here. Testing is the only way to know your home’s level. If your result is at or above 4.0 pCi/L, the next step is radon mitigation in Iowa, and the cost guide covers what a system typically runs.
Frequently Asked Questions
What is the EPA radon action level?
The EPA action level is 4.0 pCi/L. At or above that level, the EPA recommends taking steps to reduce radon in the home. Per the EPA Citizen’s Guide to Radon, homeowners may also consider fixing between 2.0 and 3.9 pCi/L.
What does pCi/L mean?
It is the unit every US radon result is reported in: picocuries per liter of air. A curie measures how fast a radioactive material decays, a picocurie is a trillionth of one, and the "per liter" makes it a concentration, how much radon is in a given volume of the air you breathe. So a result of 6 pCi/L is not six of anything you could see. It is a decay rate in your air, and the number is only meaningful next to the EPA reference points below.
What is a normal radon level, and what is high?
The EPA publishes two reference points: the average indoor level is 1.3 pCi/L and the average outdoor level is 0.4 pCi/L, with remediation recommended at 4 pCi/L (read from the EPA health risk of radon page, 2026-08-13). Iowa sits far above the national picture: the state average is around 8.5 pCi/L per Iowa HHS, so a result that would be alarming elsewhere is ordinary here, and a result near the national average is unusually good for an Iowa house.
How do I convert pCi/L to Bq/m3?
Bq/m3, becquerels per cubic meter, is the unit used in most of the world outside the US, and you will meet it in international guidance. The EPA prints both side by side: 4 pCi/L is 150 Bq/m3, the average indoor 1.3 pCi/L is 50 Bq/m3, and the average outdoor 0.4 pCi/L is 15 Bq/m3 (read from the EPA health risk of radon page, 2026-08-13).
Is any level of radon safe?
There is no completely risk-free level of radon, so lower is always better. The 4.0 pCi/L action level is the point at which the EPA recommends action, not a guarantee of safety below it.
My result is high. What now?
If your result is at or above 4.0 pCi/L, the recommended next step is mitigation. We can connect you with an NRPP-certified, Iowa HHS-credentialed specialist for a free quote.
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