Why Pennsylvania Has Some of the Highest Radon Levels in the Country

Pennsylvania consistently ranks among the top states in the nation for elevated radon levels — and most homeowners don't know it. Radon is the second leading cause of lung cancer in the United States, responsible for an estimated 21,000 deaths per year. Here's why PA is particularly at risk and what you can do about it.

What Is Radon?

Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil, rock, and water. It's invisible, odorless, and tasteless — which means the only way to know if it's in your home is to test for it.

Radon seeps into homes through cracks in foundations, gaps around pipes, sump pits, and other openings in contact with the ground. Once inside, it can accumulate to dangerous levels — especially in basements and lower floors.

Why Pennsylvania Is a High-Risk State

Several geological factors make Pennsylvania particularly susceptible to elevated radon:

• Geology: Pennsylvania sits on uranium-rich rock formations, particularly in the Reading Prong geological formation that runs through the southeastern part of the state
• Soil composition: The limestone, shale, and granite bedrock common in SE PA are known to produce higher radon levels
• Climate: Cold winters mean homes are sealed tight for months, allowing radon to accumulate without ventilation
• Basement construction: Most PA homes have basements — the lowest level where radon concentrations are highest

Radon Risk in Southeastern PA

The five counties we serve — Montgomery, Chester, Delaware, Bucks, and Berks — all have documented elevated radon levels:

• Montgomery County: Zone 1 (highest risk) — predicted average indoor radon above 4.0 pCi/L
• Chester County: Zone 1 — particularly high levels in the western and northern portions
• Bucks County: Zone 1 — elevated levels throughout, especially in upper Bucks
• Berks County: Zone 1 — consistently high readings across the county
• Delaware County: Zone 2 (moderate risk) — still above national averages

How to Protect Your Family

1. Test your home. Professional radon testing is the only way to know your levels. We use continuous radon monitors for accurate results.
2. Test every 2 years. Radon levels can change over time due to settling, construction, and seasonal variations.
3. Mitigate if needed. If levels are at or above 4.0 pCi/L, a radon mitigation system (typically sub-slab depressurization) can reduce levels by up to 99%.
4. Maintain your system. If you have a radon mitigation system, check the manometer regularly and replace the fan when needed (typically every 5-10 years).