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Radon testing when buying or selling a home: EPA guidance

EPA publishes radon testing guidelines specific to real estate, where time is short and tests can be disturbed. Ask the assistant how buyers and sellers get a reliable result.

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Answers are written by a language model solely from this base's documents, with numbered sources. They can be wrong and aren't legal, medical or financial advice: check the sources before any important decision.

Three short-term testing options for real estate

EPA's real estate radon guide offers three short-term options when results are needed quickly: two passive tests at the same time in the same place for at least 48 hours; one passive test of at least 48 hours followed immediately by a second identical test in the same spot; or a continuous monitor for at least 48 hours. With two tests, fix the home if their average is 4 pCi/L or more.

Test in the lowest level that could be used regularly, finished or unfinished, since a buyer may live lower in the home than the seller did.

Seller's results, contracts and interference

A buyer may accept the seller's earlier test if it followed the Radon Testing Checklist, but may ask for a new one if it is not recent (for example, within two years), if the home was renovated, or if a lower level will be used.

If the home is untested, EPA suggests contract provisions on where, when and by whom the test is done, how results are shared and when mitigation happens.

To prevent interference, the guide lists motion or proximity detectors and a non-interference agreement signed by the seller.

Frequently asked questions

How long must a radon test last during a home sale?

EPA says all radon tests, whether done yourself or by a qualified tester, should last a minimum of 48 hours.

How do I find a qualified radon tester or mitigation contractor?

Call your state radon office first: many states require radon professionals to be licensed, certified or registered. Elsewhere, ask about a proficiency credential or formal radon training.

What if I am buying a newly built home?

Ask the owner or builder whether it has radon-resistant features. Even a radon-resistant home should be tested after occupancy, and if a passive system tests at 4 pCi/L or more, a vent fan can make it active.

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