If you have a radon test result, the most useful question is not whether York is generally considered a radon area.
It is: What does the number measured in your home mean, and what should you do next?
Radon results are commonly reported in picocuries per liter of air (pCi/L). EPA recommends fixing a home when the radon level is 4 pCi/L or higher and considering radon reduction when the level is between 2 and 4 pCi/L.
But 4 pCi/L is an action level—not a dividing line between “safe” and “unsafe.”
This guide explains how to interpret common radon results, when another test may be appropriate, when to evaluate mitigation, and why York County maps or nearby homes cannot tell you the radon level inside your property.
What Does a Radon Test Result Mean?
A radon test measures the concentration of radon in the air.
In the United States, results are commonly reported in picocuries per liter, abbreviated pCi/L. EPA also references becquerels per cubic meter, or Bq/m³, as another unit used to express radon concentration.
The higher the measured concentration, the more radon is present in the tested air.
But interpreting a result also requires context.
The usefulness of a measurement can depend on factors such as:
- where the test was placed;
- how long the test was conducted;
- whether appropriate testing conditions were maintained; and
- whether the result should be confirmed before a decision is made.
What is pCi/L?
pCi/L stands for picocuries per liter of air. It is the standard unit commonly used to report radon concentrations in U.S. homes.
A result such as 2, 4, or 8 pCi/L describes the concentration measured during the test. It does not by itself describe the home's construction, the source of the radon, or the mitigation system that may be appropriate.
Learn More About Radon Testing in York, PAInterpretation table
Radon Level Chart — How EPA Interprets Common Results
There is no single radon number below which EPA describes exposure as completely risk-free. Instead, EPA provides an action level and guidance for reducing exposure.
| Radon level | EPA guidance | Homeowner interpretation |
|---|---|---|
| Below 2 pCi/L | Lower, but not zero risk | Continue appropriate testing practices; the result and circumstances still matter |
| 2 to under 4 pCi/L | Consider fixing | Review the result and consider reducing the radon level |
| 4 pCi/L or higher | Fix the home | Evaluate radon reduction and mitigation options |
| Much higher levels | Fix the home | A higher measured concentration gives additional reason to address the result and evaluate mitigation |
The number to remember: 4 pCi/L
EPA recommends fixing a home when its radon level is 4 pCi/L or higher.
EPA also recommends considering radon reduction when levels are between 2 and 4 pCi/L.
That means 4 pCi/L should be understood as an action level, not a boundary between harmless and harmful exposure.
What Radon Level Needs Mitigation?
For a straightforward homeowner decision point, EPA's guidance is:
4 pCi/L or higher
Fix the home.
Between 2 and 4 pCi/L
Consider fixing the home to reduce radon exposure.
What happens before mitigation may depend on the testing circumstances.
For example, you may need to consider how the original measurement was obtained and whether follow-up testing is appropriate before choosing a mitigation approach.
Once mitigation is the appropriate next step, the system itself should be designed around the property rather than selected solely from the radon number.
Why a Result Below 4 pCi/L Is Not the Same as Zero Risk
One of the most important distinctions when interpreting radon is the difference between an action level and a safe level.
EPA states that there is no known safe level of radon exposure.
That is why a result below 4 pCi/L should not be labeled “safe” or “harmless.”
In general, reducing radon concentration reduces exposure. EPA recommends considering reduction when a home tests between 2 and 4 pCi/L, even though that range is below the 4 pCi/L action level.
For homeowners, the practical interpretation is:
- lower is preferable to higher;
- 4 pCi/L is EPA's action level;
- 2–4 pCi/L is a range where reduction can still be considered; and
- no test result should be described as proof of zero radon risk.
Reference scale
How Does 4 pCi/L Compare With Typical Radon Levels?
EPA provides two useful national reference points.
~0.4
pCi/L
Typical outdoor reference
~1.3
pCi/L
U.S. indoor average
4.0
pCi/L
EPA action level
The average indoor radon concentration in U.S. homes is approximately 1.3 pCi/L.
The average outdoor radon concentration is approximately 0.4 pCi/L.
These numbers can help put a test result into context, but they need to be interpreted correctly.
1.3 pCi/L is a U.S. indoor average. It is not a York, Pennsylvania average. Likewise, the outdoor figure is a general reference point, not a prediction of the concentration at a particular York property.
A simple comparison
- ~0.4 pCi/LTypical outdoor concentration
- ~1.3 pCi/LU.S. indoor average
- 4.0 pCi/LEPA action level
These reference points help explain the scale. Your home's actual test result is what matters for a property-specific decision.
Why Your Neighbor's Result Does Not Predict Yours
Two nearby homes can produce different radon test results.
That is one reason a neighborhood, ZIP code, county statistic, or nearby test should not be substituted for testing your own property.
EPA's Map of Radon Zones was developed to identify areas with the potential for elevated indoor radon and to help governments and organizations target resources.
It was not designed to determine the radon level in an individual home.
EPA recommends that homes be tested regardless of their radon-zone designation.
Home result vs. area data
Area-level information can tell you
Whether an area has broader potential for elevated radon and provide planning context.
Area-level information cannot tell you
The radon concentration currently measured inside your home.
An individual test can tell you
The concentration measured in your property under the conditions of that test.
For a York homeowner trying to decide what to do next, the individual test result is therefore more useful than assuming your result from the surrounding area.
Local limitation
What About York County Radon Maps or Zone Data?
Radon maps can be useful for understanding broad geographic potential.
They should not be treated as home-level diagnostic tools.
A map cannot establish that a particular York home:
- has elevated radon;
- is below EPA's action level;
- needs mitigation; or
- does not need testing.
The same caution applies to county averages, ZIP-code statistics, and neighborhood-level claims.
Source limitation
We do not have a verified York-specific average from a primary source in this source pack, so we do not present one as fact.
That means this page does not claim a York County average, a York ZIP-code average, or a percentage of York homes above 4 pCi/L.
If reliable York-specific data is added in the future, it should be accompanied by its source, geography, measurement period, and methodological limitations.
When Should You Test Again?
A radon result sometimes raises a second question: Should I act on this number now, or should I test again?
Follow-up testing may be relevant when:
- an initial elevated result needs confirmation under applicable guidance;
- the original testing conditions are questionable;
- different tests produced inconsistent results;
- additional information is needed before making a mitigation decision;
- a real-estate transaction requires testing under a particular process; or
- a mitigation system has been installed and its effect needs to be measured.
The appropriate testing approach depends on the circumstances and the result.
A professional tester may also be useful when you want an independent measurement or need help following the applicable testing protocol.
What about testing after mitigation?
A mitigation system that appears to be operating does not tell you the actual indoor radon concentration.
Post-mitigation testing is used to measure the result after the system has been installed.
See How Radon Mitigation WorksAction sequence
If Your Result Is 4 pCi/L or Higher
A result at or above EPA's action level gives you a clear reason to evaluate the next step.
Confirm the Test Circumstances
Review where the test was placed, the type and duration of the test, and whether the applicable testing conditions were followed.
Determine Whether Follow-Up Testing Is Appropriate
Depending on the circumstances, another measurement may be useful before deciding how to proceed.
Review Radon Testing GuidanceEvaluate Mitigation
If mitigation is appropriate, learn how common systems reduce radon and what property conditions can affect the proposed design.
How Radon Mitigation WorksVerify Provider Certification
Pennsylvania maintains certification requirements and an official directory for professional radon services. Verify the appropriate certification rather than relying solely on a company's advertising.
How to Choose a Radon Mitigation ContractorUnderstand the Scope and Cost
A mitigation proposal should explain what system is being proposed and what is included. Cost can vary based on the property and system design.
See Radon Mitigation Cost Factors in York, PAPlan for Post-Mitigation Testing
Ask how the radon level will be measured after installation so you understand how the result of the mitigation work will be evaluated.
Verify Pennsylvania Radon Professionals
Pennsylvania DEP maintains an official Radon Services Directory that homeowners can use when checking radon professionals.
The directory includes certified radon:
- testers;
- mitigators;
- firms; and
- laboratories.
PA DEP states that the directory is updated monthly, so certification status should be checked rather than assumed from an old advertisement, website badge, or previous listing.
Official verification
PA DEP Radon Services Directory
Open PA DEP Radon Services DirectoryCertification is an important verification step, but it does not replace reviewing a proposed scope, pricing, testing plan, warranty terms, or other details before hiring a provider.
Frequently Asked Questions
Decision guide
Know the Number. Then Decide What Comes Next.
A York County map, statewide statistic, or neighbor's test can provide context, but none of them can tell you the radon concentration inside your home.
Start with the actual result.
Remember the key decision points:
Below 2 pCi/L
lower concentration, but not zero risk.
2 to under 4 pCi/L
EPA recommends considering reduction.
4 pCi/L or higher
EPA recommends fixing the home.
If your result indicates that mitigation may be appropriate, learn how the process works, understand likely cost factors, and verify the professional you are considering before committing to work.