Radon Testing Services for Homes and Commercial Buildings
Radon is the leading environmental cause of lung cancer in the United States, responsible for an estimated 21,000 deaths per year according to the EPA. It forms naturally from uranium in soil and rock, rises through the ground, and seeps into buildings through foundation cracks, sump pits, crawl spaces, and service openings. Because radon is invisible and odorless, the only way to know whether your home has elevated levels is to test. Radon testing is fast, accurate, and inexpensive — and it is the essential first step before any mitigation decision can be made. Whether you use a DIY kit or a certified measurement professional, testing gives you the data you need to protect your household.
Types of Radon Tests
Radon testing falls into two primary categories: short-term tests and long-term tests. Each serves a different purpose, and the right choice depends on your timeline and goal.
Short-Term Radon Tests (2–7 Days)
Short-term tests use charcoal canisters or electret ion chambers placed in the lowest livable area of the home for 2 to 7 days. They are the most commonly used test type for initial screening and real estate transactions. Short-term results represent the radon concentration during the testing window, which can fluctuate based on weather, season, and building conditions. For that reason, the EPA recommends following an elevated short-term result (4 pCi/L or above) with a second test before scheduling mitigation — unless the initial result is 10 pCi/L or higher, in which case mitigation should proceed without further delay.
Long-Term Radon Tests (90+ Days)
Long-term tests use alpha track detectors that remain in place for 90 days to one year. This extended window captures seasonal variation and provides the most accurate representation of average annual radon exposure in a home. Long-term testing is the preferred method when there is no urgency, such as routine monitoring of a home that has never been tested or follow-up verification after mitigation system maintenance.
Continuous Electronic Radon Monitors
Certified radon measurement professionals often use continuous electronic monitors (CEMs) that record radon levels hourly throughout the test period. These devices detect manipulation and provide tamper-resistant data, which is why they are required for many real estate transactions. CEMs can deliver certified results within 48 hours. Some homeowners also purchase consumer-grade continuous monitors for ongoing radon awareness, though these devices require periodic calibration to remain accurate.
Where and How to Place a Radon Test
Test placement significantly affects result accuracy. The EPA provides specific guidance on test placement that must be followed for results to be valid:
- Location: Test in the lowest livable area of the home — the level where occupants spend at least 4 hours per day. This may be a finished basement, first floor, or ground-level room.
- Height: Place the test device between 20 inches and 6 feet above the floor.
- Closed-house conditions: Keep windows and exterior doors closed (except for normal entry and exit) for at least 12 hours before the test begins and throughout the test period.
- Distance from openings: Keep the device at least 12 inches from exterior walls and at least 3 feet from windows, doors, and HVAC vents.
- Away from heat and humidity: Do not place the device in kitchens, bathrooms, laundry rooms, or near fireplaces.
After the test period, seal the device and mail it promptly to the certified lab included with the kit. Most labs return results within 3 to 5 business days.
Radon Testing for Real Estate Transactions
Radon testing is a standard component of home inspections in high-radon states, including Colorado, Utah, Pennsylvania, Ohio, Michigan, Minnesota, Wisconsin, and Montana. Buyers routinely request radon tests as a contingency in purchase agreements. In most cases, a certified radon measurement professional must conduct the test to satisfy lender, title, or contractual requirements.
If a test conducted during a real estate transaction reveals levels at or above 4 pCi/L, negotiation typically follows. The seller may agree to install a mitigation system before closing, reduce the sale price to allow the buyer to cover mitigation costs, or provide a radon mitigation credit at closing. If a mitigation system is already present, a post-mitigation test should confirm current system performance. See our radon mitigation services page for system installation details.
Understanding Your Radon Test Results
Radon levels are reported in picocuries per liter (pCi/L). The national average indoor radon level is 1.3 pCi/L. Here is how to interpret your results:
| Result | Interpretation | Recommended Next Step |
|---|---|---|
| Below 2 pCi/L | Low — below national average concern threshold | Retest every 2 years |
| 2–3.9 pCi/L | Moderate — EPA considers action in this range | Long-term test or consider mitigation |
| 4 pCi/L or higher | Elevated — EPA action level | Schedule mitigation |
| 10 pCi/L or higher | High — mitigate without further testing delay | Schedule mitigation immediately |
Short-term results can vary by 25–50% from long-term averages due to seasonal and weather-driven pressure changes. If a short-term result surprises you — either very high or unusually low — a confirmatory test is reasonable before committing to mitigation or concluding that no action is needed.
Frequently Asked Questions About Radon Testing
How do I test my home for radon?
Place a short-term charcoal canister or long-term alpha track detector in the lowest livable area of your home, following EPA placement guidelines. After the test period, mail the device to the certified lab included with your kit. Results arrive within 3 to 5 days. For certified documentation — required in most real estate transactions — a credentialed radon measurement professional must conduct the test using a calibrated continuous monitor.
What is a safe radon level?
The EPA action level is 4 pCi/L, but no radon level is entirely risk-free. The EPA recommends considering mitigation at 2–4 pCi/L. The WHO reference level is 2.7 pCi/L. The goal of mitigation is to achieve levels as close to outdoor air concentrations (approximately 0.4 pCi/L) as practically possible.
How long does a radon test take?
Short-term tests take 2 to 7 days. Long-term alpha track tests run for 90 days or more. Professional continuous electronic monitors can deliver certified results in 48 hours and are the standard choice for real estate closings and certification-required scenarios.
When should I test for radon?
Test now if you have never tested your home. Retest every two years after a clean result, and after any renovation, addition, HVAC change, or radon mitigation installation. Always test when buying or selling a home. Radon levels can change over time — regular testing is the only way to confirm continued safety.
Can I test for radon myself?
Yes. DIY radon test kits are widely available from hardware stores, state radon programs, and online retailers. Results from properly placed and mailed kits are reliable for screening purposes. However, certified professional testing is required for real estate transactions, court-ordered documentation, or any situation where a certified measurement record must be produced.
Get a Free Radon Quote
Have your test results back and ready to act? Or want to schedule a professional test? Complete the form below and a certified radon professional in your area will reach out promptly.
