RadonCostGuideRadon homeowner resource center
RadonCostGuide brings the pieces homeowners usually have to research separately into one place: what radon is, how testing works, what a result means, how mitigation systems work, what affects cost, what changes during a home sale, and where to find current state and professional resources.
Radon is a naturally occurring radioactive gas that can move from soil into a building through openings in and around the foundation. EPA says any home can have a radon problem—new or old, tight or drafty, with or without a basement. A map, neighborhood average, or nearby test cannot tell you the level in a specific house.
EPA recommends fixing a home when radon is 4 pCi/L (150 Bq/m³) or higher and recommends considering reduction between 2 and 4 pCi/L (75–150 Bq/m³). That does not make readings below 4 completely safe; EPA states there is no known safe level of radon exposure.
Start here
You do not need to learn everything about radon at once. Start with the question closest to your situation, then go deeper when a test result or property decision gives you a reason to.
How radon forms, how it gets into homes, and why the only reliable way to know a home's level is to test it.
Read the guide →Test your homeShort-term, long-term, DIY, and professional testing explained in plain English.
Read the guide →Read a resultUnderstand pCi/L, Bq/m³, EPA's action level, and what a first result can mean for next steps.
Read the guide →Plan a projectSee the home and installation factors that can move a mitigation project up or down in price.
Read the guide →Reading a radon result
In the United States, radon in air is commonly reported in picocuries per liter (pCi/L). Some reports use becquerels per cubic meter (Bq/m³). EPA's public guidance uses rounded equivalents of 2 pCi/L ≈ 75 Bq/m³ and 4 pCi/L ≈ 150 Bq/m³.
EPA's recommendation to consider fixing begins at 2 pCi/L. A lower result should not be described as completely safe. Conditions can change, and retesting can still make sense over time or after major changes to the home.
EPA recommends considering fixing a home in this range. Whether you confirm with additional testing and how quickly you move toward mitigation can depend on the test type, testing history, and the circumstances of the property.
At 4 pCi/L or higher, EPA recommends fixing the home. Follow-up testing and mitigation decisions should be made using appropriate testing guidance rather than treating a single number as a diagnosis of the building.
Testing
Short-term and long-term tests answer slightly different needs. A real-estate transaction may need a quicker result and more controlled procedures, while a homeowner who is not under a deadline may benefit from a longer measurement. Always follow the device instructions and applicable state requirements.
| Testing approach | What it is useful for | What to keep in mind |
|---|---|---|
| Short-term test | A quicker first measurement or time-sensitive situation. | EPA describes short-term devices as running from 2 to 90 days depending on the device. Shorter tests can be more affected by temporary conditions. |
| Long-term test | Understanding average conditions over a longer period. | Long-term tests run more than 90 days and can better reflect changing conditions across seasons and normal living patterns. |
| DIY test kit | Homeowners who can carefully follow device and laboratory instructions. | Check whether analysis, return shipping, or registration is included and whether your state has device/lab requirements. |
| Professional measurement | Real-estate transactions, complicated situations, or owners who want a professional process. | State credentialing and testing rules vary. Confirm the professional's current qualifications and the test protocol that will be used. |
EPA's current home-buying guidance says that for short-term tests lasting less than four days, windows and outside doors should be closed at least 12 hours before the test begins and remain closed except for normal entry and exit. Testing instructions and applicable professional standards should control the exact procedure for the device being used.
Mitigation
EPA generally recommends methods that prevent radon from entering the building. A common approach is soil suction: a fan and pipe system draws radon-containing soil gas from beneath the house and vents it outdoors. Crawlspace homes may use a membrane with suction beneath it. Sealing is often part of the system, but typically is not treated as the only reduction method.
The installer evaluates the slab, basement, crawlspace, additions, sump, drain tile, and other features that affect how air moves beneath the home.
One or more suction points may be connected to piping and a continuously operating fan so radon-containing soil gas is captured before it enters occupied space.
The system should have an indicator that helps show whether it is operating, and post-mitigation testing is used to determine the radon level after the work.
System performance depends on the home and installation. EPA says radon reduction systems can be highly effective, but homeowners should verify performance with testing and continue appropriate system checks and periodic retesting.
Understanding cost
EPA says mitigation cost varies with the size and design of the home and the reduction method needed. RadonCostGuide adds homeowner planning factors so you can understand why two homes—or two contractor proposals—may not cost the same.
Basement, slab, crawlspace, or mixed foundations can require different approaches.
Additions and separated slabs may require additional diagnostics or suction points.
Crawlspace systems can involve membrane work and additional sealing details.
Finished basements can make pipe routing and access more complicated.
A sump may need an appropriate sealed cover as part of the system design.
Interior and exterior routing choices can affect labor, materials, and appearance.
A fan requires a compliant power source; local electrical requirements may affect the job.
Requirements vary by jurisdiction and should be confirmed before work begins.
Important
A 12 pCi/L result does not automatically mean the system should cost three times as much as a system for a 4 pCi/L result. The contractor still has to design a system that reduces the home's radon, but project pricing is primarily driven by the physical design and installation requirements of the home.
RadonCostGuide calculator results and cost ranges are planning estimates, not contractor quotes or government-set prices. Confirm the actual scope, permits, electrical work, warranty, testing, and price with the professionals you are considering.
Buying or selling a home
EPA's Home Buyer's and Seller's Guide recommends knowing the indoor radon level of a home you are considering buying. Existing test results can be useful, but a buyer may reasonably request a new test when the previous test is old, the home has changed, test conditions are uncertain, or the buyer will occupy a lower level that was not previously tested.
Real-estate testing may also be subject to state-specific rules, professional standards, device requirements, disclosure laws, or contract deadlines. Treat those as transaction requirements—not as universal rules for every DIY homeowner test.
Read the selling-a-house-with-radon guide →State & local guidance
State programs can have different requirements for radon measurement providers, mitigation professionals, laboratories, devices, reporting, real-estate testing, permits, and public test-kit programs. EPA currently tells homeowners looking for a qualified radon service provider to start with their state radon contact and then consult the national proficiency programs.
RadonCostGuide state pages are meant to help homeowners find official state resources and public professional information. They do not replace the state agency, a credential issuer, or local permitting authority.
Hiring a radon professional
Before hiring, confirm the company is currently allowed or qualified to provide the service where your home is located, understand what the estimate includes, and make sure the proposed scope fits your home's foundation and testing history.
Common misunderstandings
EPA says its Radon Zones map is for planning and resource targeting, not for deciding whether an individual home needs testing.
Radon entry depends on the individual building and soil conditions. Nearby homes can have different results.
EPA says any home may have a radon problem, including new homes and homes without basements.
A mitigation system needs basic monitoring, and EPA recommends periodic retesting to confirm radon remains reduced.
Frequently asked questions
No. Radon cannot be reliably judged from the age of the home, whether it has a basement, a neighbor's test, or a radon-zone map. EPA says any home may have a radon problem and recommends testing homes rather than using the zone map to decide whether an individual home needs a test.
EPA uses 4 pCi/L (150 Bq/m³) as its action level and recommends fixing at or above that level. EPA also recommends considering radon reduction between 2 and 4 pCi/L because there is no known safe level of radon exposure.
Short-term tests usually run from a few days to 90 days depending on the device and are useful when a quicker result is needed. Long-term tests run more than 90 days and can provide a better picture of average conditions over time.
Not by itself. System price is driven mainly by the home and installation: foundation layout, number of sections, crawlspaces, routing, access, electrical work, permits, and the reduction method needed. A contractor still needs to design a system capable of reducing the measured level.
Sealing can be an important part of some mitigation systems, but EPA's consumer guidance generally treats sealing as a companion to other reduction techniques rather than a stand-alone solution for elevated radon.
Yes. Post-mitigation testing confirms the result of the work. EPA also advises checking the system's warning device and retesting periodically; its current FAQ says retesting at least every two years is a good idea.
Yes. States can differ in credentialing requirements, approved test devices or laboratories, real-estate procedures, disclosure rules, public test-kit programs, and other requirements. Check the official state radon program when a state-specific rule matters.
No. Directory information is informational. Homeowners should independently confirm current services, credentials, insurance, service area, permits, warranties, pricing, and availability before hiring.
Primary sources
RadonCostGuide distinguishes federal and state guidance from its own educational explanations and planning estimates. These EPA pages are the primary federal sources supporting the core guidance above.
Federal guidance reviewed August 22, 2026. State rules and program availability should be checked against current official state sources before publication or when a homeowner needs a state-specific answer.