Radon gas is an invisible health hazard that may be lurking right under your feet. Found in homes across all 50 states, radon is the second leading cause of lung cancer in the United States, after smoking. But how do you know if you’re at risk?
The answer starts with a radon levels map—a tool designed to show where radon exposure is most likely, down to the state and even zip code level.
In this guide, we’ll explain what radon is, how to interpret EPA radon maps, and most importantly, what steps you can take if your home is in a high-risk zone.
Radon is a naturally occurring, radioactive gas that forms when uranium breaks down in soil, rock, and groundwater. It moves up through the ground and can enter homes through cracks in foundations, crawlspaces, and well water systems.
Once inhaled, radon gas decays into radioactive particles that can damage lung tissue, leading to lung cancer over time. According to the EPA, radon causes over 21,000 lung cancer deaths in the U.S. annually.
A radon levels map visually shows regions of the U.S. based on their average indoor radon concentrations. The Environmental Protection Agency (EPA) uses a 3-zone system to classify radon risk by county:
Zone | Radon Potential (pCi/L) | Color on Map |
Zone 1 | > 4.0 pCi/L (High Risk) | Red |
Zone 2 | 2.0–4.0 pCi/L (Moderate) | Orange/Yellow |
Zone 3 | < 2.0 pCi/L (Low Risk) | Green |
📍 How to use it:
Zone | Meaning |
Zone 1 | Testing is strongly recommended. Most homes will have radon levels above the EPA action level (4.0 pCi/L). |
Zone 2 | Testing still recommended. Homes may test above or below action level. |
Zone 3 | Lower average risk, but testing is still advised, especially in homes with basements or crawlspaces. |
🚨 Important: No zone is considered radon-free. The EPA recommends testing every home, regardless of location.
The following states have the highest proportion of Zone 1 counties:
Even within states with generally low radon levels (e.g., Florida, Texas), localized geological conditions can lead to elevated readings in certain zip codes.
Radon gas does not cause immediate symptoms, which is why it’s often called the “silent killer.”
🧠 Fact: The risk of lung cancer increases 10x when a smoker lives in a home with high radon levels.
Testing is easy, affordable, and can save your life.
Method | Cost | Accuracy | Time Required |
DIY Short-Term Kit | $15–$25 | Moderate | 2–7 days |
DIY Long-Term Kit | $25–$40 | High | 90+ days |
Professional Test | $150–$250 | Highest | 2–7 days |
The EPA recommends action if your radon levels test at 4.0 pCi/L or higher. However, even levels between 2.0–4.0 may still pose health risks.
🛠️ Cost to fix: Professional radon mitigation ranges from $800 to $2,500, depending on the home.
You can’t see, smell, or taste radon—but it may be present in your home right now. Knowing your area’s radon level is the first step toward protecting your family’s health.
✅ Check the EPA radon map
✅ Order a radon test kit
✅ Act quickly if levels are elevated
👉 Take control of your indoor air quality. Test your home for radon in 2025 and stay safe.