R
RadonVerdict

Radon Levels Parent Guide

Radon Levels: What 2.0, 4.0, and 8.0 pCi/L Mean

Use this page to translate a radon test result into a practical next step, then open state and county pages backed by official measurement tables, CDC summaries, or official radon maps.

Interpret My Number Browse State Maps

Fast Answer

Under 2.0 pCi/L

Lower concern, but retest periodically because home levels change.

2.0 to 3.9 pCi/L

Retest or track long-term. Reduction can still be worth considering.

4.0+ pCi/L

Start mitigation planning. This is the main EPA action threshold.

Find your local answer

Popular radon level searches

These are the searches that should land on the levels hub, get a plain answer, and then continue to cost, credit, or county evidence.

Open state directory

What does 4.0 pCi/L radon mean?

It is the main EPA action threshold, so the next step is confirmation if needed and mitigation planning.

Interpret 4.0+ →

Is 2.5 pCi/L radon bad?

It is below the main action threshold, but not an all-clear. Retesting or long-term monitoring usually decides the next move.

See borderline range →

What does 8.0 pCi/L radon mean?

That is a high reading. Prioritize mitigation quotes and use the ZIP calculator to open the local cost path.

Price mitigation →

Radon levels by county

Use the state directory to open county pages backed by EPA zones, state measurement tables, CDC summaries, or official maps.

Browse counties →

Choose your next step

Start from the exact job, not another generic radon article.

Pick the situation that matches your home. Each route keeps the reading, deal side, or foundation clue attached so the next page answers the search instead of resetting the user.

Failed inspection

I need a repair or seller credit number

Open the local credit path with a 4.0+ buyer scenario already selected.

Open negotiation route

4.0+ pCi/L

I have a high result and need the cost path

Go straight to the county estimate, quote context, and contractor checklist.

Open cost route

2.0-3.9 pCi/L

I need to know if this number is bad

Use the level explanation first, then decide whether to retest, monitor, or price mitigation.

Open level route

No test yet

I need the first valid result

Start with kit placement, timing, closed-house conditions, and result interpretation.

Open testing route

Foundation fast lanes

Basement Slab Crawlspace

Deal fast lanes

Buyer ask Seller response

Already got a bid?

Check quote fairness

Official County Data

Every listed county page is tied to an official radon source

Coverage currently spans 3126 listed county pages. Measured counties use official state tables or CDC Tracking summaries; map-classified counties use official radon-potential categories when a county pCi/L table is not published.

97%

official support

Measured counties

3019

State tables

1112

Map classified

21

More county detail

86

CDC Environmental Public Health Tracking Network Radon Tests from Labs: 1907 Virginia Department of Health Radon Testing Results: 133 Missouri DHSS Residential Radon Testing in Missouri: 115 Kansas Environmental Public Health Tracking Radon Data: 105 Illinois IEMA-OHS Licensed Radon Measurement Dashboard: 100 North Carolina DHHS Radon Data Map: 100 Iowa HHS Radon Dashboard County Metrics: 99 Tennessee Environmental Public Health Tracking Radon Data: 95 Minnesota Department of Health Indoor Air Unit Radon Test Data: 87 More county detail needed: 86 Wisconsin Department of Health Services Indoor Radon Test Results: 72 Colorado Environmental Public Health Tracking Pre-Mitigation Radon Test Results: 64 New York State Department of Health Residential Radon Test Data: 62 Pennsylvania DEP Radon Test Data by ZIP Code: 50 Utah EPHT Radon Test Kit Results: 29 New Jersey DEP Radon Potential Municipality Tier Table: 21 EPA/USGS Mississippi Residential Radon Survey: 1

Open Official-Data States First

Route from the national threshold to state-specific radon data

Some states publish county measurements, while others are best read through CDC Tracking or official radon-potential maps. Start with the states below when you need county pages with clearer public data behind the recommendation.

IA Iowa HHS medians NC NCDHHS highs PA DEP ZIP data IL state results CO CDPHE data UT EPHT results

State measurements

Iowa HHS publishes county median radon values. Osceola County, IA shows an 11.4 pCi/L median, so its page should be opened before treating Iowa as only a zone-map question.

Highest measured examples

North Carolina DHHS maps the highest measured radon level by county. Rutherford County, NC shows 681 pCi/L as a high-end county signal, not a county average.

CDC and map coverage

CDC summaries and official state/federal radon-potential maps still help when a state does not publish a county measurement table. Use them as context, then let a home test decide.

National Data Guide

Start with the national action threshold, then open states with the strongest county evidence.

This page connects the plain 2.0, 4.0, and 8.0 pCi/L answer to state hubs where county evidence is strongest: 3040 of 3126 surfaced county pages have official evidence, with 3019 measured county summaries and 21 official map-classification summaries.

3019

measured counties

Official source base

Official source base: 1112 county summaries come from state-specific or federal measurement tables, 1907 use CDC Tracking, 21 use official state or federal map classifications, and 86 need more county-specific detail. That helps users tell the difference between a county with reported test data and a broader map guide.

How to use it

Official coverage is strong enough to use, but lighter-evidence counties should keep clear source caveats until more detailed county tables are available.

Where county detail is lighter

Some counties still depend on broader federal summaries or state pages without county pCi/L metrics. In those cases, use the county page as context and let a fresh home test control the decision.

Open these state hubs first

States with the strongest county evidence

Ranked by official coverage, measured county pages, elevated/high county count, and state measurement strength.

TX

254 CDC summaries

Strong evidence

254/254 counties with official support

254 measured, 0 map-classified

36 elevated/high, 27 high

TX is a strong starting point because it has 27 counties with high measured radon signals and 0 state measurement summaries.

VA

133 state measurement summaries

Start here

133/133 counties with official support

133 measured, 0 map-classified

75 elevated/high, 50 high

VA is a strong starting point because it has 50 counties with high measured radon signals and 133 state measurement summaries.

KY

120 CDC summaries

Strong evidence

120/120 counties with official support

120 measured, 0 map-classified

81 elevated/high, 62 high

KY is a strong starting point because it has 62 counties with high measured radon signals and 0 state measurement summaries.

IL

100 state measurement, 2 CDC

Start here

102/102 counties with official support

102 measured, 0 map-classified

85 elevated/high, 72 high

IL is a strong starting point because it has 72 counties with high measured radon signals and 100 state measurement summaries.

KS

105 state measurement summaries

Start here

105/105 counties with official support

105 measured, 0 map-classified

83 elevated/high, 58 high

KS is a strong starting point because it has 58 counties with high measured radon signals and 105 state measurement summaries.

MO

115 state measurement summaries

Start here

115/115 counties with official support

115 measured, 0 map-classified

75 elevated/high, 47 high

MO is a strong starting point because it has 47 counties with high measured radon signals and 115 state measurement summaries.

GA

159 CDC summaries

Strong evidence

159/159 counties with official support

159 measured, 0 map-classified

51 elevated/high, 27 high

GA is a strong starting point because it has 27 counties with high measured radon signals and 0 state measurement summaries.

MN

87 state measurement summaries

Start here

87/87 counties with official support

87 measured, 0 map-classified

85 elevated/high, 64 high

MN is a strong starting point because it has 64 counties with high measured radon signals and 87 state measurement summaries.

Direct Answer

What radon level should homeowners act on?

In US guidance, 4.0 pCi/L or higher is the main action threshold for fixing a home. Results from 2.0 to 3.9 pCi/L still deserve attention because radon risk is not zero below 4.0; retest, track long-term, or consider reduction depending on the home and situation.

Evidence Value
Under 2.0 pCi/L Lower concern; keep periodic testing
2.0 to 3.9 pCi/L Retest, track, or consider reduction
4.0+ pCi/L EPA action threshold for fixing the home
8.0+ pCi/L High reading; prioritize mitigation planning

Sources

Result Meaning

What your radon number means

No result yet? Read the testing guide
Reading
Plain meaning
Next step
Under 2.0
Below the range where most homeowners start pricing mitigation, but not a permanent all-clear.
Keep the result, retest after major home changes, and consider periodic monitoring.
2.0-3.9
Borderline range. It is below the main EPA action threshold, but risk is not zero.
Retest with a valid setup, use a long-term monitor, or price mitigation if the home has compounding risk.
4.0-7.9
Elevated result. This is where mitigation planning becomes the practical next step.
Confirm the reading if needed, then compare local mitigation costs and contractor requirements.
8.0+
High reading. Waiting usually creates more risk and more negotiation friction.
Prioritize mitigation quotes. In a real-estate deal, turn the local cost range into a repair or credit ask.

4.0+ Reading

Get a Local Action Plan

Use your ZIP, foundation type, and result band to open the right county cost page.

Buying or Selling

Calculate a Seller Credit

Turn a local mitigation range into a repair ask, credit ask, or quick-close fallback.

Trust & Sources

Read the Methodology

See how public EPA, state, housing, and cost data are used across RadonVerdict.

EPA Zone Context

EPA zones are map context, not your home result

EPA radon zones estimate county-level potential. They are useful for deciding how seriously to treat local risk, but the reading inside one basement, slab home, or crawl-space home can be higher or lower than the county prediction.

1070

Zone 1 counties

Highest predicted average potential. Testing and mitigation planning deserve early attention.

1035

Zone 2 counties

Moderate predicted average potential. Borderline readings should not be dismissed.

1033

Zone 3 counties

Lower predicted average potential. Direct testing is still the deciding evidence.

Open the official EPA Map of Radon Zones

State and County Maps

Browse radon levels by state

3126 county pages currently available in the state map directory.

AK 23 counties AL 67 counties AR 75 counties AZ 15 counties CA 58 counties CO 64 counties DE 3 counties FL 67 counties GA 159 counties HI 5 counties IA 99 counties ID 44 counties IL 102 counties IN 92 counties KS 105 counties KY 120 counties LA 64 counties MA 14 counties MD 24 counties ME 16 counties MI 83 counties MN 87 counties MO 115 counties MS 82 counties MT 56 counties NC 100 counties ND 53 counties NE 93 counties NH 10 counties NJ 21 counties NM 33 counties NV 17 counties NY 62 counties OH 88 counties OK 77 counties OR 36 counties PA 67 counties RI 5 counties SC 46 counties SD 65 counties TN 95 counties TX 254 counties UT 29 counties VA 133 counties VT 14 counties WA 39 counties WI 72 counties WV 55 counties WY 23 counties

Sources and limits

This page uses EPA radon action-level guidance and EPA zone data for public-risk context. It is not medical advice, legal advice, or a substitute for a valid home radon test. If you already have a result, your own measured level matters more than the county zone.

EPA radon resources WHO Handbook on Indoor Radon RadonVerdict methodology

Editorial and Data Transparency

Author
RadonVerdict Data Team (Public Data and Cost Modeling)
Content Review
Source-level dates shown below
Data Retrieved At
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Primary Sources