Why radon runs high in York County

Why does radon run high in York County?

EPA puts all of York County in Zone 1, its highest radon potential. In Zone 1 counties, EPA predicts the average indoor screening level is above 4 pCi/L. That's the level where EPA says to fix your home.

PA DEP's own test results say the same thing. DEP publishes radon results by zip code, from short-term tests taken between January 1990 and December 2025. Of the 42 zip codes mostly inside York County, DEP has results for 36. In every one of those 36, the average basement result is 4 pCi/L or higher. The zip averages run from 4.3 to 24 pCi/L.

A zip average isn't your house. PA DEP says radon levels can vary greatly from home to home, and the only way to know your level is to test.

What is radon?

Radon is a radioactive gas. You can't see it, smell it or taste it. It comes from the natural breakdown of uranium in soil, rock and water, and gets into the air you breathe.

How does radon get into a house?

PA DEP says the air pressure inside your home is usually lower than in the soil around the foundation. So your house acts like a vacuum and draws radon in through cracks and other openings.

DEP lists these ways in:

• Cracks in solid floors
• Construction joints
• Cracks in walls
• Gaps in suspended floors
• Gaps around service pipes
• Cavities inside walls
• The water supply

Soil gas is the main cause of radon problems. Radon can also come in through well water, and in a small number of homes from building materials, though DEP says those rarely cause a problem by themselves.

Why is radon a health risk?

When you breathe radon, it breaks down into radioactive particles that can get trapped in your lungs. PA DEP says these release small bursts of energy that can damage lung tissue and lead to lung cancer over a lifetime.

Your risk depends mostly on three things, according to DEP:

• How much radon is in your home
• How much time you spend at home
• Whether you smoke or have ever smoked

If you smoke and your home has high radon, DEP says your risk of lung cancer is especially high.

What should you do next?

Test your home. EPA says all homes should be tested, whatever the zone. Then compare your number with what your radon number means.