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

How long does a short-term radon test stay in your home?

Two days to 90 days, depending on the device.

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  1. Only about one hour
  2. At least one full year
  3. Two days to 90 days ✔

Why: Short-term tests run from two days to 90 days. Radon changes by day and season, so a long-term test (over 90 days) better shows your year-round average.

Huh, didn't know that: Charcoal canisters are commonly used for short-term radon tests, and alpha track and electret detectors for long-term ones.

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Why did the kid throw his clock out the window? To see time fly.
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References

Answer: Two days to 90 days. Short-term tests run from two days to 90 days. Radon changes by day and season, so a long-term test (over 90 days) better shows your year-round average.

  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
    Short-term tests remain in your home for two days to 90 days, depending on the device.
    Checked 2026-10-10.

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