York RadonPractical radon guidance for York, PA homeowners

Interpreting a radon test result

What Does My Radon Level Mean?

Your test came back with a number in picocuries per liter (pCi/L) — the unit used to measure radon in air. The higher the number, the more radon is present. Here's what that number actually means, using EPA guidance.

The radon scale

The EPA groups radon results into three ranges. Where your number falls determines what, if anything, you should do next.

pCi/LOpen-ended — there is no upper limit
  • Under 2 pCi/L — the EPA notes that reducing radon below 2 pCi/L is difficult even with mitigation, so this range is not generally a trigger for action. That said, the EPA is explicit that there is no known safe level of radon exposure — a low reading isn't the same as a zero reading.
  • 2 to 4 pCi/L — the EPA says to consider fixing your home in this range. It's a judgment call, not an automatic requirement.
  • 4 pCi/L or higher — the EPA recommends fixing your home. This is the "action level" you'll see referenced most often. There's no ceiling on this range — a 6 and a 20 get the same guidance, just with different margin above 4. If your result is in this range, here's what to do next, in order.

Direct from the EPA: "Fix your home if your radon level is 4 picocuries per liter (pCi/L) or higher. Consider fixing if your level is between 2 and 4 pCi/L."

Source: U.S. EPA, "EPA Map of Radon Zones and Supplemental Information" (epa.gov/radon/epa-map-radon-zones-and-supplemental-information)

What does your number mean?

Type your result below to see where it falls on the scale above.

Check what your number means

Whether your result is a 5 or a 20, both fall in the same 4+ range and get the same EPA guidance. EPA information indicates that commonly used mitigation techniques can reduce radon to 2 pCi/L or less in most homes — though no specific result can be guaranteed for any individual property. See how radon mitigation works.

Free York homeowner resource

Already have your result? Take it one step further.

Knowing where your number falls is the first half. The free Radon Ready Kit is the second: a one-page decision tree that turns your result — and the kind of test it came from — into the specific next step for your situation.

Get the Free Radon Ready Kit

16 pages, PDF, no cost. Your result stays with you: the kit is built so you write your own numbers down on paper.

Should you test again?

Test resultYou get a number in pCi/L
Which range is it in?Under 2 · 2–4 · 4+
At or above 4? Consider a second testEspecially if the first was a short-term test — levels can vary with season and weather
Confirmed elevated? MitigationA system is designed to bring the level down regardless of the exact starting number

A single test is a snapshot, not a certainty — a second data point helps you act with more confidence before deciding on next steps. Read the full radon testing guide for how short-term and long-term tests differ and what to do after mitigation.

General guidance drawn from EPA radon testing materials; see the Testing Guide page for detailed sourcing.

When mitigation enters the decision

If your result is at or above 4 pCi/L — confirmed by a second test if you had reason to want one — mitigation is the EPA's recommended path. A mitigation system doesn't just mask the problem; it's designed to actively reduce the radon entering your home, typically through a vent pipe and fan system that redirects soil gas away from your living space before it gets in. See exactly how that works, step by step, including how you confirm afterward that it's actually working.

Know your number. Ready for next steps?

If your result is at or above 4 pCi/L, there's a specific order to work through — confirm the result first, then decide about mitigation.

What to do after a high radon result