Is Radon Gas in Your Home? Here's How to Know for Sure
✓ Your concern is understandable. Radon Gas is classified as a critical health risk — testing is the only way to confirm your exposure level.
You're not overreacting. Radon Gas is invisible and odorless — the EPA recommends every homeowner test for it regardless of age or condition of the home.
The test kit below can tell you in 48 hours whether your home has elevated levels. Testing is the only way to know for sure.
Radon Gas is a critical-severity indoor air quality hazard that the EPA classifies as requiring immediate action. It is most commonly found in basement, crawl-space, living-room and originates from uranium decay in soil, cracks in foundation, sump pumps.
Radon is the #2 cause of lung cancer after smoking. It seeps from soil into basements and crawl spaces. You cannot see, smell, or taste it. The only way to know is to test.
Your family may be breathing radon gas right now.
First Alert Radon Gas Test Kit
This test kit gives you results in 48 hours. Testing is recommended by the EPA as the first step for any suspected hazard.
Compare options →Prefer a free assessment first? Take the Air Quality Risk Score Quiz →
Symptoms to Watch For
If you or your family members are experiencing any of these, radon gas could be the cause:
Quick Reference Data
| Hazard | Radon Gas |
| EPA Severity | CRITICAL |
| Common Sources | uranium decay in soil, cracks in foundation, sump pumps, well water, construction joints |
| Affected Areas | basement, crawl-space, living-room, bedroom, dining-room, pantry, utility-room, sunroom, laundry, home-office, garage |
| Health Symptoms | lung cancer (long-term), persistent cough, hoarseness, shortness of breath, chest pain |
| EPA Recommendation | Test every home for radon. If levels are 4 pCi/L or higher, install a radon mitigation system. Even levels between 2-4 pCi/L warrant action. Test every 2 years. |
Your Children Breathe 20,000 Liters of This Air Every Day
Kids breathe more air per pound of body weight than adults. Their lungs are still developing. If radon gas is in your home, they're getting a higher dose than you are. You childproof cabinets and plug outlets — but have you checked what they're breathing?
⚠️ The EPA estimates indoor air can be 2–5× more polluted than outdoor air. Your family breathes 20,000 liters of indoor air every day.
If radon gas is present, every breath could be doing damage you can't see or feel — until it's too late.
Where It Hides in Your Home
Common Sources
- • uranium decay in soil
- • cracks in foundation
- • sump pumps
- • well water
- • construction joints
What the EPA Recommends
EPA-Recommended Actions
Test every home for radon. If levels are 4 pCi/L or higher, install a radon mitigation system. Even levels between 2-4 pCi/L warrant action. Test every 2 years.
Sources & Citations
- 📎 EPA — Radon Information (epa.gov)
- 📎 EPA — Radon Zones by State (epa.gov)
- 📎 CDC — Radon and Health (cdc.gov)
- 📎 EPA — Indoor Air Quality (general)
All data on this page is based on publicly available information from the cited sources. This page is not endorsed by the EPA, CDC, or WHO.
📋 Our Testing Methodology
Hazard severity classifications follow the EPA's Indoor Air Quality assessment framework:
- • Critical: Immediate health risk — evacuate and contact emergency services
- • High: Chronic exposure risk — test within 1 week, remediate within 30 days
- • Moderate: Potential risk — test to confirm, address if confirmed
Product recommendations are based on published detection accuracy, third-party test results, and EPA-recommended testing methods. Updated November 2026.
Test Kits & Protection
EPA recommends testing as the first step for any suspected radon gas exposure. These are the tools most homeowners start with.
First Alert Radon Gas Test Kit
EPA-listed short-term radon test. Lab fees included. Results in days.
Airthings Corentium Home Radon Detector
Continuous digital radon monitoring. No lab fees. Real-time readings.
RadonAway RP140 Radon Mitigation Fan
Professional-grade radon mitigation fan. 4-inch. The core component of any radon reduction system. Cuts radon levels by up to 99%.
Guidance sourced from EPA, CDC, and Health Canada publications.
Your Home Air Defense Kit
These 3 items help you monitor and improve your indoor air.
LEVOIT Core 300-P HEPA Air Purifier
A true HEPA filter captures 99.97% of airborne particles — dust, pollen, mold spores, and pet dander. Running one in your main living space is the single most effective step you can take for cleaner indoor air.
Get the Air Purifier — Breathe Cleaner at Home → First Alert Radon Gas Test Kit
Radon is the second leading cause of lung cancer and you can't smell or see it. This EPA-listed test kit gives you results in days — know your levels before it becomes a problem you can't undo.
Test for Radon — What You Don't Know Can Hurt You → Digital Moisture Meter
Hidden moisture behind walls and under floors is how mold problems start. A pin-type moisture meter lets you catch elevated readings early — before you see or smell the damage.
Get the Moisture Meter — Stop Mold Before It Starts →Your home may have hidden hazards you can't see, smell, or taste.
Our Room-by-Room Scanner checks every corner of your home for 20+ air quality hazards.
Scan My Home Now →One more thing — your home may have related hazards
If your home has radon gas, there's a chance it also has carbon monoxide (co). Both can thrive in the same conditions. When you test for one, check for the others too.
Related Hazards
Carbon Monoxide (CO)
CO is a silent killer — colorless, odorless, and lethal at high concentrations. It binds to hemoglobin 200x more than oxygen. Every home with fuel-burning appliances needs a CO detector.
Basement Air Quality Hazards
Basements accumulate the worst indoor air hazards: radon, mold, chemical storage fumes, and pest allergens. Because warm air rises, basement pollutants circulate throughout the entire home through the stack effect.
Asbestos Fibers
Asbestos causes mesothelioma, lung cancer, and asbestosis. Homes built before 1980 likely contain asbestos in insulation, floor tiles, and pipe wrapping. Disturbing it releases deadly fibers into the air.
High Indoor Humidity
Humidity above 60% creates ideal conditions for mold, dust mites, and bacteria. It also increases off-gassing of VOCs from furniture and building materials. The EPA recommends 30-50% indoor humidity.
How Radon Gas Compares to Related Hazards
Radon Gas is classified as CRITICAL — the highest severity tier for indoor air hazards. Of the 4 related hazards we track, 2 carry a lower severity rating. This means radon gas should be your top testing priority if you suspect any indoor air quality issue.
Both Radon Gas and Carbon Monoxide (CO) carry the same critical severity classification. Their combined presence in your home creates a compounding effect that exceeds the risk of either alone. Both are commonly found in garage, basement, laundry. Addressing one without testing for the other leaves a blind spot in your home's air quality.
Shared locations: garage, basement, laundry, bedroom, dining room, utility room, crawl space, sunroom, home office
Radon Gas poses a higher immediate risk than Basement Air Quality Hazards. While both require attention, radon gas is classified as critical severity versus basement air quality hazards's high rating. If you test for one, the EPA recommends testing for the other simultaneously — they share common areas like basement, crawl space, laundry.
Shared locations: basement, crawl space, laundry, bedroom
Both Radon Gas and Asbestos Fibers carry the same critical severity classification. Their combined presence in your home creates a compounding effect that exceeds the risk of either alone. Both are commonly found in basement, laundry, living room. Addressing one without testing for the other leaves a blind spot in your home's air quality.
Shared locations: basement, laundry, living room, garage, crawl space, utility room, sunroom
Radon Gas poses a higher immediate risk than High Indoor Humidity. While both require attention, radon gas is classified as critical severity versus high indoor humidity's moderate rating. If you test for one, the EPA recommends testing for the other simultaneously — they share common areas like basement, laundry, crawl space.
Shared locations: basement, laundry, crawl space, sunroom, pantry, utility room, bedroom, garage
Severity classifications follow EPA Indoor Air Quality assessment standards. Related hazards share environmental conditions but may require different testing methods.
What Your Radon Gas Test Results Mean
After testing for radon gas, you'll receive a measurement or a positive/negative result. Here's how to interpret what that number means for your home and family.
No Detection / Clear
No radon gas was detected in your test. Your home is currently clear of this specific hazard.
What to do: Re-test annually or after any renovation, water damage, or structural change. Radon Gas can appear at any time due to uranium decay in soil or cracks in foundation.
Trace Detection
Trace amounts of radon gas were found. Even at low levels, a critical-severity hazard like this warrants prompt investigation of uranium decay in soil, cracks in foundation, sump pumps.
What to do: Locate and eliminate the source immediately. Test every home for radon. If you cannot identify the source, contact a licensed professional.
Elevated / At Action Level
Your test shows elevated radon gas at or above the EPA action level. At this concentration, the health risk is significant and immediate steps are required.
What to do: Do not delay. Test every home for radon. Contact a licensed remediation professional within 24 hours. Evacuate if you experience lung cancer (long-term) or persistent cough.
Interpretation guidelines are based on EPA standards for radiological hazards. For radon gas, test every home for radon. Always confirm results with a certified professional.
Radon Gas Exposure Limits & Key Numbers
Published reference values from EPA, WHO, CPSC, OSHA and CDC — the same numbers professionals use to interpret a test result.
Radon action levels: EPA vs WHO
| Radon level (pCi/L) | Equivalent (Bq/m³) | What it means | Source |
|---|---|---|---|
| 4.0 pCi/L | 148 Bq/m³ | EPA action level — fix your home | EPA |
| 2.7 pCi/L | 100 Bq/m³ | WHO reference level — mitigation worth considering | WHO |
| 1.3 pCi/L | 48 Bq/m³ | Average radon level inside US homes | EPA |
| 0.4 pCi/L | 15 Bq/m³ | Typical outdoor air | EPA |
1 pCi/L = 37 Bq/m³. The EPA recommends fixing any home that tests at or above 4.0 pCi/L; professional sub-slab depressurization typically costs $800–$2,500.
Estimated lifetime lung cancer risk from radon exposure
| Radon level | Never-smokers | People who smoke |
|---|---|---|
| 10 pCi/L | about 18 in 1,000 | about 260 in 1,000 |
| 4 pCi/L | about 7 in 1,000 | about 62 in 1,000 |
| 2 pCi/L | about 4 in 1,000 | about 32 in 1,000 |
| 1.3 pCi/L | about 2 in 1,000 | about 20 in 1,000 |
EPA Citizen's Guide estimates. Radon risk multiplies with smoking risk — the combination is far deadlier than either alone.
Reference tables compiled from EPA — Radon Information; EPA — Radon Zones by State; CDC — Radon and Health and the agency guidelines cited above.
Questions Homeowners Ask About Radon Gas
What are the symptoms of radon gas?
Common symptoms of radon gas include: lung cancer (long-term), persistent cough, hoarseness, shortness of breath, chest pain. If you are experiencing these symptoms, test your home and consult a healthcare provider.
How do I test my home for radon gas?
Common sources include: uranium decay in soil, cracks in foundation, sump pumps, well water, construction joints. You can test using the products recommended above. Test every home for radon. If levels are 4 pCi/L or higher, install a radon mitigation system. Even levels between 2-4 pCi/L warrant action. Test every 2 years.
Is radon gas dangerous to children?
Yes. Children are especially vulnerable to radon gas because their respiratory systems are still developing and they breathe more air per pound of body weight than adults. Radon is the #2 cause of lung cancer after smoking. It seeps from soil into basements and crawl spaces. You cannot see, smell, or taste it. The only way to know is to test.
What is an acceptable radon level in a home?
The EPA's action level is 4.0 pCi/L — fix your home at or above it. The WHO reference level is lower, 2.7 pCi/L (100 Bq/m³), and many mitigators recommend acting below 4.0 if you can. The average US home measures about 1.3 pCi/L, and outdoor air about 0.4.
How accurate are home radon test kits?
Short-term charcoal canister kits (2–7 days) give a valid snapshot but can swing with weather and open windows. Long-term alpha-track kits (90+ days) better represent your true exposure. Follow the kit's placement instructions exactly, keep windows closed for 12 hours before a short-term test, and confirm any high short-term result with a second test or a long-term kit before mitigating.
Can I test for radon myself, or do I need a professional?
You can test yourself — DIY kits cost roughly $15–$30 and are the EPA's recommended starting point for any home. Hire a certified professional for post-mitigation verification or real-estate transaction testing, where tamper-resistant continuous monitors are standard.
Stop wondering.
Start knowing.
The data is clear. The next step is testing.
The EPA notes that radon gas can only be confirmed through testing — it's often invisible and odorless. A test kit or monitor gives you a real number instead of a guess.
1 in 15 US homes has elevated radon levels — the only way to know is to test.
Take the free Air Quality Risk Score quiz and find out what's lurking in your home.
Medical & Environmental Disclaimer
This information is for educational purposes and is based on EPA and CDC guidelines. It is not a substitute for professional environmental testing, medical advice, or remediation services. If you suspect a gas leak or carbon monoxide emergency, evacuate immediately and call 911.
Maren K. Solberg
Residential Air Quality Researcher · 10+ Years Investigating Home Environmental Hazards
Garrison F. Hale has spent over a decade researching residential air quality hazards, including mold, VOCs, radon, and combustion byproducts. He translates complex EPA and CDC guidance into clear, actionable steps for homeowners.
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