Short-Term vs Long-Term Radon Testing
Compare short-term radon tests, long-term tests and continuous monitors — how long they take, how accurate they are and when to use each.
Short-term radon tests are fast; long-term tests are more representative. Because radon changes with weather and season, the longer you measure, the closer you get to your home’s true average.
Comparison
| Short-term test | Long-term test | Continuous monitor | |
|---|---|---|---|
| Duration | 2–90 days | More than 90 days | Ongoing |
| Result | One average | One average | Repeated readings and trends |
| Best for | A quick first check, home sales | Your year-round average | Understanding changes and verifying mitigation |
Which should you use?
Start with a short-term test if you need a quick answer. If the result is 4 pCi/L or higher, the EPA recommends a follow-up test. If the result is borderline, a long-term test or continuous monitor will tell you whether action is needed.
After mitigation, a continuous monitor lets you confirm the system keeps working through every season.
Sources
- A Citizen's Guide to Radon — U.S. EPA