Last updated 2026-08-19
TL;DR
Radon mitigation lowers indoor radon, usually with a sealed pipe and fan that pulls soil gas from under a slab or crawl space and vents it above the roof. Start by learning the ANSI/AARST soil-gas standard, earning NRPP or NRSB credentials if your market uses them, and checking whether your state licenses the work. Test first. Design to the house. Confirm with a post-mitigation test. No single national license exists.
What is radon mitigation?
Radon mitigation is the building work that lowers indoor radon so people breathe less of it. In existing houses that almost always means a soil suction system. A fan draws soil gas from under a slab or from a sealed crawl space and dumps it outdoors, usually above the roof. The goal is a lower, stable indoor number. It is not a magic box. It is not air freshening.
Radon is a radioactive gas that forms from uranium in soil and rock. It rides along with soil gas and collects in basements, crawl spaces, and first floors. EPA estimates radon causes about 21,000 lung cancer deaths every year in the United States. [2] On its health-risk page EPA states, "Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates." [2] That is why the trade exists. Not because a listing agent needed a checkbox.
A system does not remove every atom. It changes pressure and flow so less soil gas gets into the living space. Most residential jobs run a fan. Passive pipes without a fan show up more in new construction. Sealing cracks helps the fan work. Sealing by itself is not a system. EPA has said that for years in the Consumer's Guide. [1]
Someone tells you mitigation is an air purifier for radon? Walk away. Somebody says one national license covers every state? Walk away faster.
How do you start radon mitigation?
You start with the house science and the paper, in that order. Read ANSI/AARST SGM-SF. Take a listed mitigation course. Sit the NRPP or NRSB exam if you want a credential buyers and some state boards recognize. Then call the state radiation or health program and ask whether the trade is licensed there. [7][5]
Do not start with a truck wrap. Do not print EPA certified on a card. EPA does not certify private mitigators. EPA writes guidance and a national goal. States and two private boards handle people. [5][2]
Next, pick a legal business form, buy a general liability policy that names radon work, and learn your local permit desk. Many cities treat the fan and roof penetration as a mechanical or electrical permit even when the state has no radon license. Confirm that at the counter. Nobody here can promise you a turnaround time.
Then practice on paper. Draw a slab. Mark suction points, pipe size, fan location, and the discharge. Write the occupant notice you will leave on the system. Write the post-mitigation test plan. The paper keeps you from improvising the parts that get people sued.
Hunting a state-by-state path? Open a real state page. Colorado shows how no single radon license still leaves contractor, permit, and credential questions on the table (How to start radon mitigation in Colorado). Connecticut is the same pattern with different desks (How to start radon mitigation in Connecticut).
What radon number actually triggers a job?
EPA recommends fixing a home at 4 pCi/L. That is the number real estate deals orbit. EPA also says to consider fixing between 2 and 4 pCi/L. WHO recommends a national reference level of 100 Bq/m3 (about 2.7 pCi/L). Neither number is a safe line. Radon has no known safe concentration. [1][4]
CDC's public radon page is blunt. Testing is the only way to know the level in a building. You cannot smell it. You cannot guess it from a ZIP code. Zone maps are planning tools, not a house test. [6]
For a contractor, the trigger is whatever the client, the lender, or the state disclosure rule says, plus your own refusal line. I would not sell a system on a single 48-hour charcoal test taken during a storm if I could help it. I would retest or run a continuous monitor. EPA's measurement guidance exists for a reason. Follow it or you will argue with your own post-test. [1]
Some clients want the number as low as possible. That is closer to the federal statute than the 4 pCi/L flyer. The Indoor Radon Abatement Act sets the national long-term goal "that the air within buildings in the United States should be as free of radon as the ambient air outside of buildings." [5] Outdoor air is often about 0.4 pCi/L. You will not hit that on every slab. Say so before you take the deposit.
How does a soil suction system work in a real house?
A typical active system is a hole in the slab (or a suction pit dug into gravel), PVC pipe, a fan, and a discharge point well above the ground, away from windows. The fan runs all the time. It lowers pressure under the slab so soil gas travels up the pipe instead of into the basement. On a crawl space you seal the ground with a membrane and pull from under the plastic. That is sub-membrane depressurization. Same physics. Different fasteners. [1][7]
Pipe size, fan curve, and the number of suction points depend on what sits under the slab. Tight soils can need more pits. Clean gravel can be easy. You find out with a communication test, not with hope. I still see people pick a fan because it was on sale. That is how you earn noise complaints and a manometer that barely moves.
Discharge location is not a style choice. The standard wants the exhaust high and away from openings so you do not pull the same gas back inside. Label the system. Leave a manometer. Tell the owner the fan is supposed to run 24 hours a day. If the U-tube goes flat, call.
Sealing sumps and obvious slab openings helps. It is not the whole job. EPA's Consumer's Guide has treated sealing alone as an unreliable standalone fix. [1] I agree. Pretty caulk still fails post-tests.
Do you need a license, or is NRPP enough?
It depends on the state, and anyone who gives you one national answer is selling a myth. Some states license or certify radon mitigators by statute. Pennsylvania requires certification under 25 Pa. Code Chapter 240. Florida addresses radon programs and related duties in section 404.056, Florida Statutes. Other states have no radon-specific license at all. [10][14]
NRPP and NRSB are private national credentials. They mean you took a listed course, passed an exam, and keep up continuing education. A lot of real estate work and a lot of state applications use one of those cards as the competency proof. They are not a state license by themselves. [7][2]
| Path | Who issues it | What it is | What it is not |
|---|---|---|---|
| NRPP mitigation | NRPP (AARST) | Course, exam, CE | A state license |
| NRSB mitigation | NRSB | Course, exam, CE | A state license |
| State radon license | State health or radiation program | Legal permission in that state | Automatically valid next door |
| EPA designation | Nobody issues this to contractors | Guidance and a national goal | A contractor card |
In an unlicensed state you may still need a contractor license or a business tax account. Cities still want permits for roof jacks and electrical hookups. Confirm with the relevant board and the building department. Do not take timing promises from a website, including this one.
Look at a licensed state before you assume yours is easy. Alabama's license question is a different packet than California's (radon mitigation license in Alabama, radon mitigation license in California). Colorado and Connecticut each run their own mix (radon mitigation license in Colorado, radon mitigation license in Connecticut).
I would get the national mitigation credential first if I planned to work across state lines. Then I would add state paper where the statute requires it. Doing it backwards wastes exam money when a state wants a specific board.
What paper do first-year operators actually keep?
Keep the records that prove you built the system and checked it, plus the records that keep you legal. That means the pre-test, a design sketch, pit and discharge photos, fan model, manometer reading, occupant instructions, and the post-test. Keep your credential, insurance, permits, and any state license packet too. AARST's SGM-SF standard is built around that kind of file. Follow it even if your state is quiet. [7]
On the business side, keep CE certificates and insurance declarations with the policy number visible. If a state licenses the trade, keep the packet the way the board wrote it. Pennsylvania publishes actual code text. Use that, not a group chat summary. [10]
Contracts should say what you will build, what test protocol you will run after, and what happens if the post-test still reads at or above 4 pCi/L. Write a rework clause. I would rather come back on a stubborn house than fight a review. Nobody has clean public success rates by soil type. The closest honest line is EPA's, that most homes can be brought under 4 pCi/L and many can go lower. [1]
Device paper matters if you test. Measurement guidance covers placement, duration, and when a test is invalid. [1] Subcontract the post-test? Still keep the report.
This is the one place a kit saves time. RadonPath publishes a $149 one-time NRPP Mitigation Kit aimed at the national credential packet. You can also print the same public applications off the NRPP site yourself. [2]
How much does a mitigation system cost the homeowner?
EPA's Consumer's Guide to Radon Reduction has published a typical range of about $800 to $2,500 for a mitigation system. That band is old enough that many markets now bid higher on large footprints and two-fan houses. Treat it as EPA's published range, then price your actual labor and materials. [1]
Your job cost is pipe, fittings, a fan, electrical, flashing, sealant, a manometer, labor, permit fees, drive time, and the post-test. Cheap fans are a false saving. A noisy fan on a bedroom wall is a callback. I would spend more on the fan and the flashing and less on vinyl lettering for the van.
Do not quote a national average on the phone. Walk the house. Look at the slab, the sump, the crawl height, the roofline, and the electrical panel. Then write a number. If a competitor is hundreds under everyone, they are skipping the post-test, the permit, or the discharge height.
| Cost piece | What it is | What I'd cheap out on |
|---|---|---|
| Fan and fittings | Continuous duty, sized to the pit | Nothing. Buy a real radon fan. |
| Electrical | Disconnect, permit if required | Decorative covers |
| Flashings and hangers | Roof weather and pipe support | Fancy pipe colors |
| Diagnostics and post-test | Communication test plus a real post-test | This is how you get sued |
| Marketing | Truck wrap, lead portals | Most of it, year one |
Confirm permit fees with the local department. They change. I will not invent them here.
Which standard should you build to?
Build residential existing-home jobs to the current ANSI/AARST SGM-SF soil gas mitigation standard. That is the document trainers, inspectors, and a growing list of state rules point at. EPA's Consumer's Guide is the homeowner explanation. It is not a construction spec. Use the guide to talk. Use SGM-SF to build. [1][7]
New construction rough-in? That is a different AARST standard family. Do not mix them. A passive stack with no fan is not an active system. Do not sell it as one.
ASTM E2121 still exists as a practice for installing systems in existing low-rise buildings. Some bid forms still name it. I would know both numbers. I would still keep SGM-SF on the truck.
Training courses that feed NRPP and NRSB are supposed to teach to these standards. If a weekend course skips diagnostics and only shows pretty pipe, pick another course. The exam will not skip it. [7][2]
Kansas State University runs National Radon Program Services, the national help desk many health departments still point to. Their mitigation page is a clean public explainer if you need something to hand a nervous seller. [12]
How do you prove the system worked?
You prove it with a post-mitigation test in the living space after the system has run long enough to stabilize. A manometer shows the fan is moving air. It does not show the indoor radon number. Follow measurement guidance. If the after result still reads 4 pCi/L or higher, go back and fix it. [7][1]
I would not start a two-day test the afternoon I left if I could avoid it. Give the house a day. Follow closed-house conditions. If a state conflict-of-interest rule stops you from testing your own work, hire an independent tester and put that in the contract. Confirm the current rule with the board. Do not guess.
Keep the before and after reports together. An install without a number is how this trade earned a bad name. CDC's basic public line still holds. Test to know. That applies after the fan as much as before. [6]
What first-year expenses are worth it, and what is a waste?
Spend money on the listed course, the exam, real fans, a micromanometer, liability insurance that names radon work, and a short contract with a rework clause. Skip most lead portals in year one. Skip any class that promises you will be EPA certified. EPA does not certify private mitigators. [2]
A waste: wrap advertising before you have ten clean post-tests, and any expensive camera pitch that substitutes for learning pressure fields. Diagnostic tools pay for themselves. A cheap micromanometer teaches you more than another logo. So does a smoke pencil.
CE is not optional if you hold NRPP or NRSB. Budget it. State licensed programs add their own renewal cycles. Confirm those dates and fees with the board. I will not invent a renewal fee here because boards change them.
Weekend work only? Still carry the insurance. One roof leak will erase a year of side-job profit. A second person on crawl jobs is worth it.
How do state rules differ from the national myth?
The myth is that radon work is federally licensed. It is not. The Indoor Radon Abatement Act set a national indoor-air goal and funded state programs. It did not create a federal contractor card. What you meet on the ground is a patchwork of state licenses, private credentials, local permits, and real estate disclosure rules. [5]
Some health departments license people. Some only list NRPP or NRSB holders. Some do almost nothing beyond public education. Building departments still own the permits. Those are different desks.
WHO's fact sheet estimates radon causes 3% to 14% of lung cancers in a country, depending on average levels and smoking rates. That is a population statement. It tells you nothing about how two neighboring states write contractor rules. [4]
So you read the state page, then the statute, then you call. I would do that before I printed invoices. Arizona's start path is not Arkansas's (how to start radon mitigation in Arizona, radon mitigation license in Arkansas). For another contrast, read Connecticut's paper path next to a state that barely mentions the trade (How to start radon mitigation in Connecticut).
Myth number two is that Zone 3 houses do not need mitigation. False. Zone maps are county-level estimates. Houses fail tests in every zone. Test the building. [6][4]
What should you do this week if you want to enter the trade?
Download SGM-SF and EPA's Consumer's Guide this week. Enroll in a listed mitigation course if you are serious. Email the state radon contact and ask whether mitigation is licensed, certified, or unlisted. Call an insurer and the local permit desk. Write down names. Then confirm every form on the board site. [1][7][12]
You now know more than people who only watched a pipe video.
Need a state walkthrough next? Use a state guide, then confirm every fee on the board site. For a western example, start with How to start radon mitigation in Colorado. For a New England paper path, use How to start radon mitigation in Connecticut.
RadonPath is an independent publisher, not a licensing board and not a mitigation company. The $149 NRPP Mitigation Kit and the rest of the start path live at /start if you want the national forms in one packet. The public board sites stay the source of truth.
Do the reading. Then do one clean house. Then keep the paper.
Frequently asked questions
What is radon mitigation?
Radon mitigation is the work of lowering indoor radon, usually by installing a fan and sealed pipe that pull soil gas from under a slab or a crawl-space membrane and vent it outdoors above the roof. The point is a lower indoor concentration, confirmed by a post-mitigation test. Sealing cracks helps the fan. Sealing alone is not mitigation. EPA's usual homeowner trigger is 4 pCi/L.
How do you start radon mitigation?
Read ANSI/AARST SGM-SF and EPA's Consumer's Guide. Take a listed mitigation course and sit the NRPP or NRSB exam if you want a national credential. Ask your state health or radiation program whether mitigation is licensed there. Form a business, buy liability insurance that names the work, and ask the local permit desk what they want for the fan and roof jack. Confirm every fee with the board.
Is radon mitigation the same as radon testing?
No. Testing measures the indoor concentration with a device and a protocol. Mitigation changes the building so less soil gas enters. Some states let one person do both. Some restrict you from testing your own mitigation work. Confirm conflict-of-interest rules with the relevant board. Keep both reports even if two different people produce them.
Can a homeowner install their own radon system?
In many unlicensed states, a homeowner can work on their own house. That does not make it smart, and it does not skip building permits. Licensed states often reserve paid work for credentialed people and may restrict even DIY. A bad discharge next to a window can feed radon back indoors. If you DIY, still follow SGM-SF and still post-test.
Does EPA license radon mitigators?
No. EPA does not license or certify private radon contractors. EPA publishes health guidance, measurement protocols, and consumer guides. The Indoor Radon Abatement Act set a national goal for indoor air. State programs and two private boards (NRPP and NRSB) handle people. Anyone advertising EPA certified mitigator is misusing the name.
What is the EPA radon action level?
EPA recommends fixing a home at 4 picocuries per liter (pCi/L). EPA also says consider action between 2 and 4 pCi/L. That 4 pCi/L figure is a policy action level, not a proven safe line. WHO's recommended national reference level is 100 Bq/m3, about 2.7 pCi/L. Outdoor air is often near 0.4 pCi/L.
How much does radon mitigation cost?
EPA's Consumer's Guide has published a typical range of about $800 to $2,500. Many markets now bid above that on large or messy houses. The number you should charge is materials, labor, permit fees, diagnostics, and a real post-test, not a national average from a phone call. Confirm local permit fees at the building department.
What is NRPP certification?
NRPP is a private national credential run with AARST. For mitigation it usually means a listed course, an exam, and continuing education. Many states and many real estate clients treat it as proof of competence. It is not, by itself, a state license. NRSB is the other national board that issues a similar card. Check which card your state application actually names.
Do you need a permit for radon mitigation?
Often yes at the city or county, even when the state has no radon license. Roof penetrations, electrical hookups, and mechanical fans trip permit desks. Some towns want nothing. Ask the local building department before you cut the roof. I will not invent a fee or a wait time. Those change by counter and by year.
How do you know a mitigation system worked?
A post-mitigation radon test in the living space, run after the system has been on long enough to stabilize, is the proof. A manometer only shows the fan is pulling. Follow measurement protocols and closed-house conditions. If the after number is still 4 pCi/L or higher, go back and add suction or fix leaks, then test again.
What is sub-slab depressurization?
It is the common active system on poured slabs. You open a suction pit through the slab, pipe it to a continuous fan, and discharge above the roof. The fan lowers pressure under the slab so soil gas goes up the pipe instead of into the house. Communication testing tells you whether one pit is enough.
Is there a national radon mitigation license?
No. There is no federal mitigator license. NRPP and NRSB are national private credentials. Some states layer a license or certification on top. Others do not. 15 U.S.C. § 2661 sets a national indoor-air goal. It does not issue contractor cards. Always confirm the current rule with the state board that actually owns the trade.
What standard covers residential radon mitigation?
ANSI/AARST SGM-SF is the soil gas mitigation standard for existing homes. That is the document I would build to. EPA's Consumer's Guide explains systems to homeowners. It is not a spec. New construction rough-in uses a different AARST standard family. Do not sell a passive stack as an active system.
Can you mitigate a crawl space for radon?
Yes. The usual method is a sealed ground membrane with suction under the plastic (sub-membrane depressurization). The fan still discharges above the roof. Edges, pier wraps, and punctures are where these jobs fail. A post-test still decides whether it worked. Tight crawl heights make this a two-person job. Budget the time.
Sources
- U.S. EPA, Consumer's Guide to Radon Reduction: EPA has published a typical residential mitigation cost range of about $800 to $2,500 and treats sealing alone as an unreliable standalone fix.
- U.S. EPA, Health Risk of Radon: EPA estimates about 21,000 U.S. lung cancer deaths per year from radon and calls radon the leading cause of lung cancer among non-smokers; EPA does not certify private mitigators.
- World Health Organization, Radon and health fact sheet: WHO recommends a national reference level of 100 Bq/m3 and estimates radon causes 3% to 14% of lung cancers depending on country conditions.
- 15 U.S.C. § 2661, Indoor Radon Abatement national goal: Federal law sets a national long-term goal that indoor air be as free of radon as outdoor air, not a federal contractor license.
- CDC, About Radon: Testing is the only way to know a building's radon level.
- AARST/ANSI SGM-SF-2023 Soil Gas Mitigation Standards for Existing Homes: SGM-SF is the current consensus standard for existing-home soil gas mitigation design, installation, and documentation.
- 25 Pa. Code § 240.101, radon certification requirement: Pennsylvania requires radon certification under Chapter 240 to offer radon services.
- Kansas State University National Radon Program Services, Mitigation: National Radon Program Services publishes public mitigation explainers used by many state health programs.
- Florida Statutes § 404.056 (2023): Florida statute 404.056 addresses radon programs, disclosure, and related state duties.