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DictionaryThe buying process

Radon: what it means

Radon is a natural radioactive gas that comes from the breakdown of uranium in soil, rock and water. You cannot see or smell it.

In Spanish it is

Radón

Also written as: radon gas · radon test

The full explanation

It usually moves up from the ground into a home through cracks and other holes in the foundation, and the home can trap it inside. Any home can have it, new or old, with or without a basement, and it is a leading cause of lung cancer. Testing is the only way to know the level. If you are buying, EPA recommends asking the seller for test results or having the home tested, and high levels can be reduced.

An example

Before closing, Luis asks the seller for the radon test results. Because the home has never been tested, his contract says who will do the test and who will pay if the radon has to be reduced.

You will see it in…

  • The radon test results the seller gives you
  • Purchase agreement clauses about radon testing
  • Information about a radon-reduction system in the home
A grandmother smiles, seated at home.

Still confused by a paper?

A HUD-approved housing counselor can walk you through it. Agencies usually charge little or nothing, many work in Spanish, and they do not sell you anything.

Official sources

We sum up what these official sources say, in plain words. We add no rules they do not state; when a rule changes, the definition and its date change.

  1. 1. U.S. Environmental Protection Agency (EPA) · Radon (external site) · in English · Verified on October 17, 2026
  2. 2. U.S. Environmental Protection Agency (EPA) · What is Radon? (external site) · in English · Verified on October 17, 2026
  3. 3. U.S. Environmental Protection Agency (EPA) · Home Buyer's and Seller's Guide to Radon (external site) · in English · Verified on October 17, 2026