SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/home-a-radon-closed

Before a 2 or 3 day radon test, how long should windows and doors stay closed?

At least 12 hours before the test begins.

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  1. Only the minute you start
  2. At least 12 hours before starting ✔
  3. At least one full week before

Why: For a short test of 2 or 3 days, close windows and outside doors at least 12 hours before starting and keep them closed as much as possible during it.

Huh, didn't know that: Do not run fans or machines that bring in outside air during a short-term test. Fans in a radon system are fine.

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References

Answer: At least 12 hours before starting. For a short test of 2 or 3 days, close windows and outside doors at least 12 hours before starting and keep them closed as much as possible during it.

  1. EPA: A Citizen's Guide to Radon (2016) www.epa.gov/sites/default/files/2016-12/documents/2016_a_citizens_guide_to_radon.pdf
    be sure to close your windows and outside doors at least 12 hours before beginning the test
    Checked 2026-10-10.

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