Understanding radon

What Is Radon, and How Does It Get Into a House?

Radon is a naturally occurring radioactive gas that comes up from the ground. It's colorless, odorless, and tasteless — which means the only way to know if it's in your home, and how much, is to test for it. Here's what it is and how it gets in.

How radon gets from the ground into your house

Radon starts in soil and rock, and works its way indoors through ordinary openings most homes have.

In the groundRadon forms naturally as uranium in soil and rock breaks down over time.

Becomes a gasIt turns into a gas that can move freely through the soil.

Pressure pulls it upwardAir pressure inside a home is often a little lower than in the soil beneath it, which can draw soil gas up and in.

Through cracks & gapsIt enters through cracks and other openings in the foundation, and through crawl spaces.

Indoor airOnce inside, it can build up in the air you breathe every day.

Sources: U.S. EPA, "How Does Radon Get Into Your Home?" (epa.gov/radon/how-does-radon-get-your-home) — "moves up through the ground... into your home through cracks and other holes in the foundation." CDC, "About Radon" (cdc.gov/radon/about) — radon enters "through small cracks or holes," including crawl spaces.

Does radon cause symptoms?

Radon exposure does not cause immediate warning symptoms, so you cannot tell whether a home has elevated radon by how you feel. Testing is how you find out. The EPA states there are no immediate symptoms from radon exposure, and that lung cancer is the only health effect definitively linked to it — something that would usually show up years (5–25) after exposure, not right away.

Radon exposure vs. lung-cancer symptoms

Lung cancer itself can eventually cause symptoms: a cough that gets worse or doesn't go away, chest pain, shortness of breath, wheezing, coughing up blood, ongoing fatigue, or unexplained weight loss. These are possible symptoms of lung cancer generally — they are not symptoms that tell you a home has radon, and the CDC notes most people with lung cancer don't have symptoms until it's advanced. If you're experiencing any of these, that's a conversation for a healthcare professional, not something this page can assess.

You can't detect radon by symptoms — here's how to test your home.

Sources: U.S. EPA, "What Are the Health Effects from Exposure to Radon?" (epa.gov/radon/what-are-health-effects-exposure-radon) — "There are no immediate symptoms from exposures to radon... Lung cancer is the only health effect which has been definitively linked with radon exposure... would usually occur years (5-25) after exposure." CDC, "Symptoms of Lung Cancer" (cdc.gov/lung-cancer/symptoms) — symptom list and "Most people with lung cancer don't have symptoms until the cancer is advanced."

Knowing radon exists doesn't tell you your number

Almost any home can have some radon, and it depends on the specific ground beneath that specific building — not just the general area. A neighboring house's level tells you nothing reliable about yours, and because radon can't be seen, smelled, or tasted, testing is the only way to find out your own number.

Already have a number? Find out what it means.

And if that number came back at or above 4 pCi/L, interpreting it is only the first half — here's what a high result actually calls for, in the order those steps happen.

Free York homeowner resource

When you're ready to move from learning to deciding

Understanding radon and working out what to do about your own house are two different jobs. If you already have a test result, the free Radon Ready Kit covers the second one: what the number means, and the next step that follows from it.

Get the Free Radon Ready Kit

A free 16-page PDF for York-area homeowners. Nothing is passed to a contractor.