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What does my radon number mean?
Radon results in the U.S. are reported in picocuries per liter of air (pCi/L). EPA recommends fixing your home at 4 pCi/L or higher and says to consider fixing between 2 and 4 pCi/L (EPA).
General information only. This page summarizes public guidance from EPA and the Ohio Department of Health. It is not professional radon or medical advice. For questions about your home, contact ODH radon education staff (614-728-0272, [email protected]) or an Ohio-licensed radon professional (ODH).
The EPA reference points
| Result | What EPA says |
|---|---|
| 4 pCi/L or higher | Fix your home. This is EPA's action level (EPA Citizen's Guide). |
| 2 to under 4 pCi/L | Consider fixing (EPA). EPA says levels below 4 pCi/L still pose some risk and in many cases can be reduced (EPA Citizen's Guide). |
| About 1.3 pCi/L | EPA's estimate of the average indoor level (EPA Citizen's Guide). |
| About 0.4 pCi/L | The level normally found in outdoor air (EPA Citizen's Guide). |
EPA's position is that no level of radon is known to be safe, and that most homes today can be brought down to 2 pCi/L or below (EPA Citizen's Guide).
Why one short test isn't the final word
Radon levels vary day to day and season to season, so a short-term test is less likely than a long-term test to reflect your year-round average (EPA). EPA's steps: if a first short-term test is 4 pCi/L or higher, follow up with a long-term test or a second short-term test before deciding. If you used two short-term tests, consider fixing when their average is 4 pCi/L or higher (EPA Citizen's Guide). Results close to 4 are the least certain: EPA notes an average of 4.1 pCi/L from two short-term tests means about a 50% chance the year-round average is somewhat below 4.
See short-term vs long-term tests for how to run the test correctly.
Why EPA treats it seriously
EPA estimates radon is the second leading cause of lung cancer overall and the leading cause among non-smokers, responsible for about 21,000 lung cancer deaths a year in the U.S. (EPA). EPA also says the risk is much higher for smokers who are exposed to radon. The practical point from EPA is that the risk can be lowered by lowering the level, and reduction systems can cut levels by up to 99% in some homes (EPA Citizen's Guide).
Ohio specifics
- ODH recommends that all occupied ground-contact buildings in Ohio be tested, and says its county and ZIP code radon maps are educational only: testing is the only way to know your home's level (ODH Radon Data).
- ODH says free radon test kits are available for Ohio homeowners; call its education staff to ask how to get one (ODH).
- ODH recommends retesting single-family homes every two years, or after significant renovations that may affect airflow (ODH Radon Data).
If your number calls for action, see how mitigation works and how to find a licensed Ohio contractor.
Sources
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