What is radon?
Radon is a colorless, odorless radioactive gas produced naturally as uranium in soil and rock breaks down. It can enter buildings through cracks, joints, gaps around service penetrations, crawl spaces and other openings in contact with the ground.
The established health risk is lung cancer.
EPA identifies radon as the second leading cause of lung cancer in the United States and the leading cause among people who have never smoked. EPA estimates roughly 21,000 U.S. lung-cancer deaths each year are radon-related. There are no immediate symptoms from radon exposure; the risk develops over years of exposure.
Why radon deserves special attention in Iowa
Iowa HHS reports that the Iowa Radon Survey found approximately 71.6% of Iowa homes at or above the EPA action level of 4.0 pCi/L. Iowa is also entirely EPA Zone 1 for radon potential. That does not mean every Iowa home is high — it means testing is especially important because neighboring homes can have very different results.
What does a result mean?
| Measured level | General interpretation |
|---|---|
| Below 2.0 pCi/L | Lower result, but radon varies over time; retesting is still recommended periodically and after major building changes. |
| 2.0–3.9 pCi/L | Below the EPA action level. EPA advises considering reduction in this range. |
| 4.0 pCi/L or higher | EPA recommends action to reduce radon. Follow-up testing and mitigation decisions depend on the measurement context. |
Radon risk is not a reason for panic. It is a reason to measure. Elevated radon can usually be reduced effectively with properly designed mitigation systems.