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How to Test Large Buildings for Radon

Placement Protocols: Placement protocols vary from state to state.  Most states instruct people testing large buildings to:

  • Place radon detectors in every frequently occupied room where the floor has contact with the soil, including edges and corners.

  • Place radon detectors in the breathing zone, 2-6 feet above the floor, and away from drafts, exterior walls, windows, sumps, drains or doors.

  • Place one radon detector for every 2000 square feet in large rooms.

Quality Assurance and Control: Some states require testers and mitigators to follow some or all of the quality assurance procedures below:

  • Duplicate tests where two radon detectors are placed in the same location.  This tests to see if the analysis process is producing consistent results.  Usually, duplicates are placed in one of every ten locations (10%) with no limit on the total number of duplicates.

  • Blank detectors are radon detectors that are not opened until just before they are returned.  Blank radon detectors test to see if the analysis process can distinguish between tracks caused by radon and background.  Frequently, the number of blanks must equal at least 5% of the total number of detectors, possibly with a cap on total number of blanks performed.

  • Spiked detectors are exposed in a certified radon chamber.  This tests to see if the analysis process is producing accurate results.  State regulations indicate the number of spikes to be tested annually, usually about 3% of the total number of detectors, possibly with a cap on total number of spikes performed.

  • Duplicate, blank, and spike QC tests should be labeled so that the analysis lab does not know which detectors are QC tests.  This may not always be possible.

Certifications and Licensing: Many states have regulations for radon testing and mitigation.  Any state radon regulations do not apply to  home testing by an owner or occupant.  State regulations also do not apply to exclusive-use federal property.  Regulations vary among:

  • States with no regulations.

  • States that require testers and mitigators to be certified by a national professional association.

  • States that require testers and mitigators to be licensed by the state.

  • States that require a separate certification for testing schools or commercial buildings.

Contact your state radon office to learn about the requirements that apply to you.

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