How Much Radon Is Too Much in a Pennsylvania Home?

When most homeowners hear the word radon, their first thought is: “Should I be worried?” And the honest answer is — it depends on how much is in your home and how long you’ve been exposed.

But let’s back up for a second.

A Real Story From the Field

A few months ago, I inspected a home in Cranberry Township where the sellers were confident their basement was safe. They’d lived there for 20 years without a single test. Out of curiosity, they added a radon test to their pre-listing inspection.

When the results came back, the levels were 6.8 pCi/L — more than one and a half times the EPA action level. They had no idea.

The look on their faces said it all: shock, worry, and relief that they caught it before listing. That moment is why I take radon testing so seriously — because you can’t see, smell, or taste it. It’s invisible, but it’s real.

What the Numbers Mean

• 0 – 1.9 pCi/L: Excellent. Typical outdoor levels.

• 2 – 3.9 pCi/L: Below EPA action level, but mitigation can still reduce exposure.

• 4 pCi/L and above: The EPA recommends corrective action — usually through a mitigation system that vents gas safely outside.

Even if your level is under 4, the World Health Organization suggests mitigation at 2.7 pCi/L or higher.

Why Radon Levels Vary So Much

• Soil composition – Western Pennsylvania’s glacial soils and shale pockets trap radon.

• Foundation style – Basements, crawlspaces, and even slabs can act like chimneys.

• Seasonal pressure changes – Cold-weather heating draws more gas inside.

That’s why testing is recommended every two years or any time a home’s structure or HVAC system changes.

What Testing Looks Like

At Keystone Castle Inspections, we use Continuous Radon Monitors (CRMs) that record hourly readings over 48 hours. They’re tamper-resistant and provide a detailed graph showing how levels fluctuate day and night. Once testing ends, we review the data and deliver a clear report with next-step recommendations.

What to Do If Levels Are High

1. Don’t panic. Radon is common and highly fixable.

2. Hire a DEP-certified mitigation professional. Most systems install in a day or two.

3. Retest afterward to verify results drop below 4 pCi/L (ideally under 2).

The cost usually ranges between $900 – $3,000, depending on foundation type and layout — a small investment in your family’s health and property value.

The Takeaway

The only way to know your home’s radon level is to test it. It’s not about fear — it’s about awareness.

Just like those sellers in Cranberry Township, peace of mind starts with information.

Thinking about testing your home?

📅 Schedule a Continuous Radon Monitor test online at www.keystonecastleinspections.com — it takes less than two minutes to book, and results are typically ready within 48 hours.