Post-mitigation testing · Lincoln, Nebraska
Verify the reduction—then keep checking the system.
A pressure gauge can show that an active system is moving air. Only a new radon measurement shows whether the level in the home was reduced.
The first verification window
Test soon enough to check the installation.
EPA’s Consumer’s Guide says a post-mitigation radon test should be completed within 30 days of installation, but no sooner than 24 hours after the system is operating with its fan on, when it has one.
For this effectiveness check, EPA recommends a two- to seven-day measurement. The guide also recommends an independent follow-up measurement to avoid a potential conflict of interest.
Follow the device and professional protocol. EPA’s guide calls for closed windows and doors for 12 hours before and during this test, except for normal entry and exit.
- 01
Let the system operate
Keep an active fan running continuously and wait at least 24 hours before the first verification measurement.
- 02
Protect test conditions
Confirm the device instructions, test location, start time, end time, and required closed-building conditions.
- 03
Keep the result
Save the report with the system diagram, installer information, operating instructions, and warranty records.
The ongoing check
A passing first test is a baseline—not the end of testing.
EPA says it is a good idea to retest a mitigated home at least every two years to make sure radon levels remain low. Keep checking the system’s visible warning device between measurements.
If the indicator changes, the fan becomes unusually quiet or noisy, or a later result rises, review the whole-system check before assuming the fan alone is the cause.
Changes that reset the baseline
Retest after work that can change the pressure boundary.
EPA advises retesting after major structural changes or a remodel to confirm that construction did not reduce the system’s effectiveness. Examples can include finishing a basement, changing a foundation area, or adding new conditioned space; ask a qualified professional how the specific project affects the system.
Keep one property record
- Pre-mitigation result and test conditions
- System layout and operating instructions
- First post-mitigation result
- Dated two-year retest results
- Repairs, remodels, and system changes
Official guidance
Use current public sources and licensed businesses.
EPA provides the timing and maintenance guidance used on this page. Nebraska DHHS maintains state radon information and lists of licensed measurement and mitigation businesses.
- EPA: Consumer’s Guide to Radon Reduction
- Nebraska DHHS: Radon program and licensed-business resources
- Lincoln-Lancaster County Health Department: indoor air and radon guidance
Source review: July 19, 2026. This page is general planning information, not a test report, system inspection, or represented contractor service.
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