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RADON411

Independent U.S. radon data

Radon levels by county and ZIP code, and how to test and fix your home

Radon411 is an independent U.S. radon data site: the EPA radon zone and reported radon tests for every county, plain guides to radon testing and radon mitigation, and certified radon professionals with their published certifications. A dated PDF report for one place costs $5.

See the radon levels for your county or ZIP code

Radon in 30 seconds

The second leading cause of lung cancer, and you cannot see, smell or taste it

Radon is a colorless, odorless, tasteless gas produced by the decay of naturally occurring uranium in soil and water. It is the second leading cause of lung cancer after smoking, and testing is the only way to know your level.

How to test for radon

EPA estimate

About21,000

lung cancer deaths a year in the U.S. are caused by radon.

  • Second only to smoking as a cause of lung cancer.
  • The number one cause among people who never smoked: about 2,900 deaths a year.
EPA estimates of U.S. lung cancer deaths a year: radon about 21,000, with an uncertainty range of 8,000 to 45,000; secondhand smoke about 3,000.
How radon causes lung cancer

EPA estimate

Nearly1 in 15

U.S. homes is estimated to have an elevated radon level.

Testing is the only way to know, and every radon test runs for at least 48 hours.

How to test your home

EPA action level

4pCi/L

Fix a home at or above it. Consider a fix between 2 and 4.

On a scale of radon in picocuries per liter: outdoor air about 0.4, the average home about 1.3, consider fixing between 2 and 4, fix at 4 or higher.

Up to 99% lower: some radon reduction systems can cut a home's level that far, EPA says.

What your level means

Radon products

Every radon test kit, monitor and fan we cover

Each one has its own page with the maker's figures, how it measures and its independent test status.

See all products

Compare up to four side by sideWhich test to use

Short-term kitFirst Alert

RD1 short-term charcoal radon test kit

  • Lab fee included

The First Alert RD1 is a short-term, do-it-yourself charcoal radon test: you leave the sampler on the lowest level of your home for two to four days, then mail it to the laboratory, and the lab fee is included except for New Jersey's state fee.

Measures by:
Activated charcoal
In the home:
2 to 4 days
Check price on Amazon (opens in a new tab)

Short-term kitKidde

442020 short-term charcoal radon test kit

  • Lab fee included

Kidde's 442020 is a mail-in, short-term radon test: an activated charcoal sampler bag you leave in place for three days, then post to Alpha Energy Laboratories, which mails the result back.

Measures by:
Activated charcoal sampler
In the home:
3 days

Long-term kitPRO-LAB

RL116 long-term radon test kit

The PRO-LAB RL116 is a long-term, do-it-yourself radon test: one detector that starts the moment you open its bag, stays in place for three to twelve months, and goes back to PRO-LAB's laboratory in a prepaid envelope.

Measures by:
Passive detector in a sealed bag
In the home:
3 to 12 months

MonitorAirthings

Corentium Home 2 battery digital radon monitor

C-NRPP 2024/25: Not included
  • Battery
  • Screen and app
  • Bluetooth

The Corentium Home 2 is Airthings' battery-powered radon detector: two AA batteries, an alpha spectrometry sensor, an LCD screen with 24-hour to long-term averages, and Bluetooth to the Airthings app, plus temperature and humidity.

Measures by:
Alpha spectrometry
Readings:
Samples radon every 60 minutes
Check price on Amazon (opens in a new tab)

MonitorAirthings

View Plus radon and air quality monitor

C-NRPP 2024/25: Approved
  • Battery
  • Screen and app
  • Wi-Fi and Bluetooth

The View Plus is Airthings' seven-sensor monitor: radon by alpha spectrometry, plus particulate matter (PM2.5), carbon dioxide, VOCs, temperature, humidity and air pressure, on a 2.9-inch e-paper screen with Wi-Fi.

Measures by:
Alpha spectrometry
Check price on Amazon (opens in a new tab)

MonitorAranet

Radon One battery digital radon monitor with an e-ink screen

C-NRPP 2024/25: Not included
  • Battery
  • Screen and app
  • Bluetooth

The Aranet Radon One is a battery-powered, radon-only monitor from SAF Tehnika's Aranet line: an ionization chamber that counts alpha decay events, an always-on E-Ink screen, and Bluetooth to the free Aranet Home app, with no Wi-Fi or outlet needed.

Measures by:
Alpha decay event detection with an ionization chamber
First reading:
Within 10 minutes
Check price on Amazon (opens in a new tab)

MonitorAranet

Radon Plus battery digital radon monitor with an e-ink screen

C-NRPP 2024/25: Approved
  • Battery
  • Screen and app
  • Bluetooth

The Aranet Radon Plus is a battery-powered radon monitor from SAF Tehnika's Aranet line: an ionization chamber that counts alpha decay events, an always-on E-Ink screen, temperature and humidity, and Bluetooth to the free Aranet Home app.

Measures by:
Alpha decay event detection with an ionization chamber
First reading:
Within 10 minutes
Check price on Amazon (opens in a new tab)

MonitorForensics Detectors

FD-65-RADON rechargeable radon detector with a color screen

C-NRPP 2024/25: Not included
  • Battery
  • Screen

The FD-65-RADON is a pocket-sized radon detector from Forensics Detectors, a California maker of gas detectors: a semiconductor sensor that counts alpha decay by natural diffusion, a 2-inch color screen, an alarm, and a built-in battery charged over USB-C.

Measures by:
Alpha-decay event detector with a radon semiconductor sensor
First reading:
Within 6 hours
Check price on Amazon (opens in a new tab)

MonitorX-Sense

XR0A-iR Wi-Fi battery radon detector with a screen

C-NRPP 2024/25: Not included
  • Battery
  • Screen and app
  • Wi-Fi

The XR0A-iR is X-Sense's Wi-Fi radon detector: the same passive diffusion chamber and continuous alpha spectrometry X-Sense lists for its other radon detectors, a digital display, three AA batteries, and remote readings and alerts in the X-SENSE Home Security app.

Measures by:
Continuous alpha spectrometry
First reading:
Within 24 hours
Check price on Amazon (opens in a new tab)

MonitorX-Sense

XR0B-SR battery digital radon monitor with an alarm

C-NRPP 2024/25: Not included
  • Battery
  • Screen

The XR0B-SR is X-Sense's battery radon detector with a built-in alarm: three AA batteries, a passive diffusion chamber read by continuous alpha spectrometry, and an LCD screen that pairs a long-term average with rolling 1, 7, 30 and 90-day averages.

Measures by:
Continuous alpha spectrometry
First reading:
Within 24 hours
Check price on Amazon (opens in a new tab)

Radon fanFantech

Rn2 inline radon mitigation fan

  • 3 or 4 in. schedule 40 PVC, with Fantech LDVI couplings (sold separately)
  • 59 W

The Rn2 is Fantech's mid-range inline fan for active soil depressurization: a sealed plastic housing with an external rotor motor, made for 3 or 4 inch PVC pipe and rated by Fantech for indoor, outdoor and wet locations.

Check price on Amazon (opens in a new tab)

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Start here

Start with your situation

Choose the one closest to yours. Each opens the guide written for it.

Your area

Radon zones and tests for all 3,231 U.S. counties

EPA puts every county in one of three zones by its predicted average indoor radon level. A zone is a prediction for the whole county, not a reading of any home. Every state and county has a free page: choose yours on the map, type it, or find it in the list.

Map of the United States with every county shaded by its EPA radon zone: Zone 1 red, Zone 2 amber, Zone 3 pale.AlabamaAlaskaArizonaArkansasCaliforniaColoradoConnecticutDelawareDistrict of ColumbiaFloridaGeorgiaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaPuerto RicoRhode IslandSouth CarolinaSouth DakotaTennesseeTexasU.S. Virgin IslandsUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming
Predicted: EPA Map of Radon Zones, every U.S. county. Choose a state in the field above or the list to open its page.Choose a state to open its page.
  • Zone 1Highest predicted potential, predicted greater than 4 pCi/L1,071counties
  • Zone 2Moderate predicted potential, predicted 2 to 4 pCi/L1,034counties
  • Zone 3Lower predicted potential, predicted less than 2 pCi/L1,033counties
  • No zone on fileEPA has published no zone for these93counties

Measured: tests of other buildings are on file for 2,862 counties, never a reading of your home.

An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.

Open the radon map
Every state and territory, by region56
Northeast9
Midwest12
South17
West13
Territories5

Four steps

Learn, test, fix, find a pro

The whole path, from a county report to a confirmed fix in your own home.

  1. Learn

    Know what radon is

    What radon is, how it gets indoors, and why a county zone is not a reading for your home.
    Learn about radon

  2. Test

    Test the building you live in

    Short-term or long-term, where the device goes, and closed-house conditions.
    How to test

  3. Fix

    Bring a high level down

    How a mitigation system works, and the retest that confirms it.
    How mitigation works

  4. Find a pro

    Hire a certified professional

    Measurement and mitigation professionals by state, with their certifications.
    Find a professional

Guides

A guide for every topic

Plain answers on what radon is, how to test a home and how to bring a high level down.

See all guides, by topic

Get help

People and tools for the job

Radon411 does not certify anyone or perform tests. It lists what is published, so you can compare and choose.

  • Professionals

    Certified radon professionals

    2,461 measurement and mitigation businesses are listed, each with its certification shown the way the certifying body published it.

    Find a professional

  • Products

    Test kits, monitors and fans

    23 radon products are compared on their published specifications, each on its own page with how it works and, for a monitor, its independent test status. Affiliate links are labeled where they appear.

    See every product

Your next step

Look up the place you care about

Every state and county has a free report: its predicted zone, the tests on file and what to do next.

Find your county