---
title: "What Is Radon? A Pennsylvania Homeowner's Guide"
description: "Radon is a natural radioactive gas and a leading cause of lung cancer. Learn how it enters PA homes and what EPA and PA DEP recommend."
canonical: https://radonroster.com/what-is-radon/
---

# What is radon?

Radon is a radioactive gas that comes from the natural breakdown of uranium in soil and rock. You can't see, smell or taste it. It moves up through the ground and can enter homes through cracks in foundations, gaps around pipes, sumps and other openings, and it can build up indoors.

## Why it matters

EPA identifies radon as the leading cause of lung cancer among non-smokers and estimates it causes about 21,000 lung cancer deaths in the U.S. each year ([EPA: Health Risk of Radon](https://www.epa.gov/radon/health-risk-radon)).

## Radon in Pennsylvania

PA DEP says Pennsylvania has one of the most serious radon problems in the country, with an estimated 40% of homes tested above EPA's action guideline of 4 picocuries per liter (pCi/L) ([PA DEP Radon Division](https://www.pa.gov/agencies/dep/programs-and-services/radiation-protection/radon-division)). See [radon test data for your county](https://radonroster.com/pa/radon-levels-by-county/).

## What to do

1. Test your home (DIY kit or a [DEP-certified tester](https://radonroster.com/pa/counties/)).
2. If results are 4 pCi/L or higher, confirm with a second test as PA DEP describes on its [Radon in the Home](https://www.pa.gov/agencies/dep/programs-and-services/radiation-protection/radon-division/radon-in-the-home) page.
3. If confirmed, hire a DEP-certified mitigator. Pennsylvania law requires anyone doing radon testing, mitigation or lab analysis for the public to be DEP-certified ([25 Pa. Code Chapter 240](https://files.dep.state.pa.us/RadiationProtection/BureauOfRadiationProtection/BRPPortalFiles/Chapter_240_2015-04-23.pdf)).

PA DEP Radon Hotline: 800-237-2366.