What Is Radon?
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil, rock, and groundwater. It is colorless, odorless, and tasteless. It enters homes through cracks in foundations, gaps around pipes, and other openings where the building contacts the ground.
The U.S. Environmental Protection Agency (EPA) estimates that radon causes approximately 21,000 lung cancer deaths per year in the United States, making it the second leading cause of lung cancer after smoking (EPA, 2003).
Radon can accumulate in any home — new or old, with or without a basement — in every state. Learn what happens if elevated radon goes unaddressed →
How to Know If Your Home Has Radon
You cannot see, smell, or taste radon. The only way to know your home’s radon level is to test. The EPA and the U.S. Surgeon General recommend testing all homes below the third floor.
Key facts:
- Nearly 1 in 15 U.S. homes has a radon level at or above the EPA action level of 4 pCi/L.
- Radon levels vary house to house — your neighbor’s result does not predict yours.
- Short-term tests take 2–7 days. Long-term tests take 90 days to one year.
- Testing costs $15–$50 for a DIY kit, or $150–$300 for professional testing.
How to know if you have a radon problem — risk factors, test types, and what your results mean →
Schedule a professional radon test →
How to Test Your Home for Radon
Step 1: Choose a Test Type
- Short-term test (2–7 days): Charcoal canisters or continuous radon monitors. Best for a quick screening.
- Long-term test (90+ days): Alpha track detectors or electret ion chambers. More accurate annual average.
Step 2: Prepare the Testing Area
Close all windows and exterior doors at least 12 hours before testing. Keep them closed throughout the test except for normal entry and exit. Do not run fans that bring in outside air.
Step 3: Place the Test Device
Set the device at least 20 inches above the floor in the lowest livable level. Keep it away from exterior walls, high humidity areas, and direct drafts. Avoid kitchens, bathrooms, and laundry rooms.
Step 4: Send to Lab or Read Results
DIY kits are sealed and mailed to a lab (results in 1–2 weeks). Continuous monitors and professional testers provide faster results.
Step 5: Interpret Your Results
| Radon Level (pCi/L) | EPA Recommendation |
|---|---|
| Below 2 | Low risk. No action needed. Retest every 2–5 years. |
| 2 to 3.9 | Moderate risk. Consider mitigation. Confirm with a long-term test. |
| 4 and above | Action level. The EPA recommends mitigation. |
| 8 and above | High risk. Mitigate as soon as possible. |
The WHO recommends action at 2.7 pCi/L (100 Bq/m³). There is no known safe level of radon exposure.
How Radon Mitigation Works
The most common and effective method is Active Soil Depressurization (ASD). A pipe is inserted through the foundation slab into the soil beneath. An inline fan creates continuous negative pressure, drawing radon gas up through the pipe and venting it above the roofline where it disperses harmlessly.
A properly installed ASD system reduces indoor radon by 80–99%.
Other methods include sub-membrane depressurization (crawlspaces), heat recovery ventilators, and sealing cracks — though sealing alone is never sufficient as a standalone fix.
Compare the top radon mitigation systems and how they work →
Learn about radon mitigation services →
Specialized Services
Not every home fits the standard install. House Radon connects homeowners with professionals who handle:
- New construction radon systems → — passive and active radon-resistant features for new builds
- Commercial radon mitigation → — schools, offices, multi-unit buildings
- Radon fan installation and replacement → — upgrading or replacing worn-out fans
- Radon system repair → — diagnosing and fixing underperforming systems
What Radon Mitigation Costs
| Service | Typical Cost Range |
|---|---|
| Professional radon test | $150–$300 |
| DIY radon test kit | $15–$50 |
| Standard ASD mitigation system | $800–$2,500 |
| Complex installation (multiple suction points, difficult routing) | $2,500–$5,000+ |
| Annual fan replacement (if needed) | $150–$400 |
| Post-mitigation retest | $50–$150 |
Costs vary by region, foundation type, and home size. Some states offer radon mitigation tax credits or financial assistance — check with your state radon program.
See what real homeowners are paying — Reddit’s radon mitigation cost breakdown →
When to Call a Professional
If your test result is 4 pCi/L or above, hire a licensed or certified radon mitigation contractor. Look for:
- NRPP (National Radon Proficiency Program) or NRSB (National Radon Safety Board) certification
- State-specific licensing where required
- Written proposal with system design, warranty, and post-mitigation testing
- Liability insurance and references
Do not attempt to install a mitigation system yourself. Improper installation can fail to reduce radon or create new problems like back-drafting combustion appliances.
Find certified radon mitigation professionals near you →
Radon by State
Radon levels are driven by local geology. The EPA classifies U.S. counties into three zones:
- Zone 1 (highest potential): Predicted average indoor level above 4 pCi/L
- Zone 2 (moderate potential): Predicted average between 2–4 pCi/L
- Zone 3 (low potential): Predicted average below 2 pCi/L
Zone classification does not replace testing. High-radon homes exist in every zone.
State guides:
- Radon mitigation in Pennsylvania → — one of the highest-radon states in the U.S.
- Radon mitigation in Utah → — elevated risk across the Wasatch Front and mountain valleys
More state guides coming soon for Ohio, Colorado, Minnesota, Michigan, Kentucky, Montana, North Dakota, and Wisconsin.
Frequently Asked Questions
Q: Can I test for radon myself?
A: Yes. DIY test kits cost $15–$50 at hardware stores or online. For real estate transactions, use a certified professional tester.
Q: How long does radon mitigation take?
A: Most residential ASD systems are installed in 3–6 hours. Post-mitigation testing begins 24–48 hours later.
Q: Does radon mitigation really work?
A: Yes. A properly installed ASD system reduces radon by 80–99%. Most homes drop well below 2 pCi/L after mitigation.
Q: Is radon only a problem in basements?
A: No. Any floor that contacts the ground can have elevated radon, including slab-on-grade homes.
Q: Do new homes have radon?
A: Yes. New construction is not radon-proof. Some new homes include passive radon systems, but they still require testing and may need a fan added. Learn about new construction radon systems →
Q: How often should I retest?
A: Every 2–5 years, after major renovations, and after installing a mitigation system (test at 24–48 hours, 30 days, then every 2 years).
Q: Will a radon system affect my home’s resale value?
A: A functioning system is viewed positively by buyers. Many states require radon disclosure during real estate transactions.
Q: Does homeowner’s insurance cover radon mitigation?
A: Generally no. Some states offer financial assistance or tax credits. Contact your state radon program for details.
Get a Free Radon Test Quote
Every home should be tested. If your radon level is 4 pCi/L or above, a certified mitigation system can reduce it by up to 99%.
Enter your zip code, property type, and contact information. A certified radon professional in your area will follow up within one business day.
Sources
- U.S. Environmental Protection Agency. A Citizen’s Guide to Radon. Updated 2024.
- U.S. EPA. EPA Map of Radon Zones. Updated 2024.
- World Health Organization. WHO Handbook on Indoor Radon. 2009.
- U.S. EPA. Health Risk of Radon. Updated 2024.
- National Radon Proficiency Program (NRPP). Find a Radon Professional.
This page is for informational purposes only and does not constitute professional environmental advice. Always consult a certified radon professional for testing and mitigation decisions specific to your property.